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199 commits
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64fe24a3e0 |
mm/mprotect: try avoiding write faults for exclusive anonymous pages when changing protection
Similar to our MM_CP_DIRTY_ACCT handling for shared, writable mappings, we can try mapping anonymous pages in a private writable mapping writable if they are exclusive, the PTE is already dirty, and no special handling applies. Mapping the anonymous page writable is essentially the same thing the write fault handler would do in this case. Special handling is required for uffd-wp and softdirty tracking, so take care of that properly. Also, leave PROT_NONE handling alone for now; in the future, we could similarly extend the logic in do_numa_page() or use pte_mk_savedwrite() here. While this improves mprotect(PROT_READ)+mprotect(PROT_READ|PROT_WRITE) performance, it should also be a valuable optimization for uffd-wp, when un-protecting. This has been previously suggested by Peter Collingbourne in [1], relevant in the context of the Scudo memory allocator, before we had PageAnonExclusive. This commit doesn't add the same handling for PMDs (i.e., anonymous THP, anonymous hugetlb); benchmark results from Andrea indicate that there are minor performance gains, so it's might still be valuable to streamline that logic for all anonymous pages in the future. As we now also set MM_CP_DIRTY_ACCT for private mappings, let's rename it to MM_CP_TRY_CHANGE_WRITABLE, to make it clearer what's actually happening. Micro-benchmark courtesy of Andrea: === #define _GNU_SOURCE #include <sys/mman.h> #include <stdlib.h> #include <string.h> #include <stdio.h> #include <unistd.h> #define SIZE (1024*1024*1024) int main(int argc, char *argv[]) { char *p; if (posix_memalign((void **)&p, sysconf(_SC_PAGESIZE)*512, SIZE)) perror("posix_memalign"), exit(1); if (madvise(p, SIZE, argc > 1 ? MADV_HUGEPAGE : MADV_NOHUGEPAGE)) perror("madvise"); explicit_bzero(p, SIZE); for (int loops = 0; loops < 40; loops++) { if (mprotect(p, SIZE, PROT_READ)) perror("mprotect"), exit(1); if (mprotect(p, SIZE, PROT_READ|PROT_WRITE)) perror("mprotect"), exit(1); explicit_bzero(p, SIZE); } } === Results on my Ryzen 9 3900X: Stock 10 runs (lower is better): AVG 6.398s, STDEV 0.043 Patched 10 runs (lower is better): AVG 3.780s, STDEV 0.026 === [1] https://lkml.kernel.org/r/20210429214801.2583336-1-pcc@google.com Link: https://lkml.kernel.org/r/20220614093629.76309-1-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Suggested-by: Peter Collingbourne <pcc@google.com> Acked-by: Peter Xu <peterx@redhat.com> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Yang Shi <shy828301@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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5a90d5a103 |
mm/hugetlb: handle UFFDIO_WRITEPROTECT
This starts from passing cp_flags into hugetlb_change_protection() so hugetlb will be able to handle MM_CP_UFFD_WP[_RESOLVE] requests. huge_pte_clear_uffd_wp() is introduced to handle the case where the UFFDIO_WRITEPROTECT is requested upon migrating huge page entries. Link: https://lkml.kernel.org/r/20220405014906.14708-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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019c2d8b95 |
mm/shmem: allows file-back mem to be uffd wr-protected on thps
We don't have "huge" version of pte markers, instead when necessary we split the thp. However split the thp is not enough, because file-backed thp is handled totally differently comparing to anonymous thps: rather than doing a real split, the thp pmd will simply got cleared in __split_huge_pmd_locked(). That is not enough if e.g. when there is a thp covers range [0, 2M) but we want to wr-protect small page resides in [4K, 8K) range, because after __split_huge_pmd() returns, there will be a none pmd, and change_pmd_range() will just skip it right after the split. Here we leverage the previously introduced change_pmd_prepare() macro so that we'll populate the pmd with a pgtable page after the pmd split (in which process the pmd will be cleared for cases like shmem). Then change_pte_range() will do all the rest for us by installing the uffd-wp pte marker at any none pte that we'd like to wr-protect. Link: https://lkml.kernel.org/r/20220405014852.14413-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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fe2567eb55 |
mm/shmem: allow uffd wr-protect none pte for file-backed mem
File-backed memory differs from anonymous memory in that even if the pte is missing, the data could still resides either in the file or in page/swap cache. So when wr-protect a pte, we need to consider none ptes too. We do that by installing the uffd-wp pte markers when necessary. So when there's a future write to the pte, the fault handler will go the special path to first fault-in the page as read-only, then report to userfaultfd server with the wr-protect message. On the other hand, when unprotecting a page, it's also possible that the pte got unmapped but replaced by the special uffd-wp marker. Then we'll need to be able to recover from a uffd-wp pte marker into a none pte, so that the next access to the page will fault in correctly as usual when accessed the next time. Special care needs to be taken throughout the change_protection_range() process. Since now we allow user to wr-protect a none pte, we need to be able to pre-populate the page table entries if we see (!anonymous && MM_CP_UFFD_WP) requests, otherwise change_protection_range() will always skip when the pgtable entry does not exist. For example, the pgtable can be missing for a whole chunk of 2M pmd, but the page cache can exist for the 2M range. When we want to wr-protect one 4K page within the 2M pmd range, we need to pre-populate the pgtable and install the pte marker showing that we want to get a message and block the thread when the page cache of that 4K page is written. Without pre-populating the pmd, change_protection() will simply skip that whole pmd. Note that this patch only covers the small pages (pte level) but not covering any of the transparent huge pages yet. That will be done later, and this patch will be a preparation for it too. Link: https://lkml.kernel.org/r/20220405014850.14352-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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5c041f5d1f |
mm: teach core mm about pte markers
This patch still does not use pte marker in any way, however it teaches the core mm about the pte marker idea. For example, handle_pte_marker() is introduced that will parse and handle all the pte marker faults. Many of the places are more about commenting it up - so that we know there's the possibility of pte marker showing up, and why we don't need special code for the cases. [peterx@redhat.com: userfaultfd.c needs swapops.h] Link: https://lkml.kernel.org/r/YmRlVj3cdizYJsr0@xz-m1.local Link: https://lkml.kernel.org/r/20220405014833.14015-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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c9fe66560b |
mm/mprotect: do not flush when not required architecturally
Currently, using mprotect() to unprotect a memory region or uffd to unprotect a memory region causes a TLB flush. However, in such cases the PTE is often not modified (i.e., remain RO) and therefore not TLB flush is needed. Add an arch-specific pte_needs_flush() which tells whether a TLB flush is needed based on the old PTE and the new one. Implement an x86 pte_needs_flush(). Always flush the TLB when it is architecturally needed even when skipping a TLB flush might only result in a spurious page-faults by skipping the flush. Even with such conservative manner, we can in the future further refine the checks to test whether a PTE is present by only considering the architectural _PAGE_PRESENT flag instead of {pte|pmd}_preesnt(). For not be careful and use the latter. Link: https://lkml.kernel.org/r/20220401180821.1986781-3-namit@vmware.com Signed-off-by: Nadav Amit <namit@vmware.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will@kernel.org> Cc: Yu Zhao <yuzhao@google.com> Cc: Nick Piggin <npiggin@gmail.com> Cc: Andrew Cooper <andrew.cooper3@citrix.com> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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4a18419f71 |
mm/mprotect: use mmu_gather
Patch series "mm/mprotect: avoid unnecessary TLB flushes", v6. This patchset is intended to remove unnecessary TLB flushes during mprotect() syscalls. Once this patch-set make it through, similar and further optimizations for MADV_COLD and userfaultfd would be possible. Basically, there are 3 optimizations in this patch-set: 1. Use TLB batching infrastructure to batch flushes across VMAs and do better/fewer flushes. This would also be handy for later userfaultfd enhancements. 2. Avoid unnecessary TLB flushes. This optimization is the one that provides most of the performance benefits. Unlike previous versions, we now only avoid flushes that would not result in spurious page-faults. 3. Avoiding TLB flushes on change_huge_pmd() that are only needed to prevent the A/D bits from changing. Andrew asked for some benchmark numbers. I do not have an easy determinate macrobenchmark in which it is easy to show benefit. I therefore ran a microbenchmark: a loop that does the following on anonymous memory, just as a sanity check to see that time is saved by avoiding TLB flushes. The loop goes: mprotect(p, PAGE_SIZE, PROT_READ) mprotect(p, PAGE_SIZE, PROT_READ|PROT_WRITE) *p = 0; // make the page writable The test was run in KVM guest with 1 or 2 threads (the second thread was busy-looping). I measured the time (cycles) of each operation: 1 thread 2 threads mmots +patch mmots +patch PROT_READ 3494 2725 (-22%) 8630 7788 (-10%) PROT_READ|WRITE 3952 2724 (-31%) 9075 2865 (-68%) [ mmots = v5.17-rc6-mmots-2022-03-06-20-38 ] The exact numbers are really meaningless, but the benefit is clear. There are 2 interesting results though. (1) PROT_READ is cheaper, while one can expect it not to be affected. This is presumably due to TLB miss that is saved (2) Without memory access (*p = 0), the speedup of the patch is even greater. In that scenario mprotect(PROT_READ) also avoids the TLB flush. As a result both operations on the patched kernel take roughly ~1500 cycles (with either 1 or 2 threads), whereas on mmotm their cost is as high as presented in the table. This patch (of 3): change_pXX_range() currently does not use mmu_gather, but instead implements its own deferred TLB flushes scheme. This both complicates the code, as developers need to be aware of different invalidation schemes, and prevents opportunities to avoid TLB flushes or perform them in finer granularity. The use of mmu_gather for modified PTEs has benefits in various scenarios even if pages are not released. For instance, if only a single page needs to be flushed out of a range of many pages, only that page would be flushed. If a THP page is flushed, on x86 a single TLB invlpg instruction can be used instead of 512 instructions (or a full TLB flush, which would Linux would actually use by default). mprotect() over multiple VMAs requires a single flush. Use mmu_gather in change_pXX_range(). As the pages are not released, only record the flushed range using tlb_flush_pXX_range(). Handle THP similarly and get rid of flush_cache_range() which becomes redundant since tlb_start_vma() calls it when needed. Link: https://lkml.kernel.org/r/20220401180821.1986781-1-namit@vmware.com Link: https://lkml.kernel.org/r/20220401180821.1986781-2-namit@vmware.com Signed-off-by: Nadav Amit <namit@vmware.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrew Cooper <andrew.cooper3@citrix.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Peter Xu <peterx@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will@kernel.org> Cc: Yu Zhao <yuzhao@google.com> Cc: Nick Piggin <npiggin@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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6c287605fd |
mm: remember exclusively mapped anonymous pages with PG_anon_exclusive
Let's mark exclusively mapped anonymous pages with PG_anon_exclusive as exclusive, and use that information to make GUP pins reliable and stay consistent with the page mapped into the page table even if the page table entry gets write-protected. With that information at hand, we can extend our COW logic to always reuse anonymous pages that are exclusive. For anonymous pages that might be shared, the existing logic applies. As already documented, PG_anon_exclusive is usually only expressive in combination with a page table entry. Especially PTE vs. PMD-mapped anonymous pages require more thought, some examples: due to mremap() we can easily have a single compound page PTE-mapped into multiple page tables exclusively in a single process -- multiple page table locks apply. Further, due to MADV_WIPEONFORK we might not necessarily write-protect all PTEs, and only some subpages might be pinned. Long story short: once PTE-mapped, we have to track information about exclusivity per sub-page, but until then, we can just track it for the compound page in the head page and not having to update a whole bunch of subpages all of the time for a simple PMD mapping of a THP. For simplicity, this commit mostly talks about "anonymous pages", while it's for THP actually "the part of an anonymous folio referenced via a page table entry". To not spill PG_anon_exclusive code all over the mm code-base, we let the anon rmap code to handle all PG_anon_exclusive logic it can easily handle. If a writable, present page table entry points at an anonymous (sub)page, that (sub)page must be PG_anon_exclusive. If GUP wants to take a reliably pin (FOLL_PIN) on an anonymous page references via a present page table entry, it must only pin if PG_anon_exclusive is set for the mapped (sub)page. This commit doesn't adjust GUP, so this is only implicitly handled for FOLL_WRITE, follow-up commits will teach GUP to also respect it for FOLL_PIN without FOLL_WRITE, to make all GUP pins of anonymous pages fully reliable. Whenever an anonymous page is to be shared (fork(), KSM), or when temporarily unmapping an anonymous page (swap, migration), the relevant PG_anon_exclusive bit has to be cleared to mark the anonymous page possibly shared. Clearing will fail if there are GUP pins on the page: * For fork(), this means having to copy the page and not being able to share it. fork() protects against concurrent GUP using the PT lock and the src_mm->write_protect_seq. * For KSM, this means sharing will fail. For swap this means, unmapping will fail, For migration this means, migration will fail early. All three cases protect against concurrent GUP using the PT lock and a proper clear/invalidate+flush of the relevant page table entry. This fixes memory corruptions reported for FOLL_PIN | FOLL_WRITE, when a pinned page gets mapped R/O and the successive write fault ends up replacing the page instead of reusing it. It improves the situation for O_DIRECT/vmsplice/... that still use FOLL_GET instead of FOLL_PIN, if fork() is *not* involved, however swapout and fork() are still problematic. Properly using FOLL_PIN instead of FOLL_GET for these GUP users will fix the issue for them. I. Details about basic handling I.1. Fresh anonymous pages page_add_new_anon_rmap() and hugepage_add_new_anon_rmap() will mark the given page exclusive via __page_set_anon_rmap(exclusive=1). As that is the mechanism fresh anonymous pages come into life (besides migration code where we copy the page->mapping), all fresh anonymous pages will start out as exclusive. I.2. COW reuse handling of anonymous pages When a COW handler stumbles over a (sub)page that's marked exclusive, it simply reuses it. Otherwise, the handler tries harder under page lock to detect if the (sub)page is exclusive and can be reused. If exclusive, page_move_anon_rmap() will mark the given (sub)page exclusive. Note that hugetlb code does not yet check for PageAnonExclusive(), as it still uses the old COW logic that is prone to the COW security issue because hugetlb code cannot really tolerate unnecessary/wrong COW as huge pages are a scarce resource. I.3. Migration handling try_to_migrate() has to try marking an exclusive anonymous page shared via page_try_share_anon_rmap(). If it fails because there are GUP pins on the page, unmap fails. migrate_vma_collect_pmd() and __split_huge_pmd_locked() are handled similarly. Writable migration entries implicitly point at shared anonymous pages. For readable migration entries that information is stored via a new "readable-exclusive" migration entry, specific to anonymous pages. When restoring a migration entry in remove_migration_pte(), information about exlusivity is detected via the migration entry type, and RMAP_EXCLUSIVE is set accordingly for page_add_anon_rmap()/hugepage_add_anon_rmap() to restore that information. I.4. Swapout handling try_to_unmap() has to try marking the mapped page possibly shared via page_try_share_anon_rmap(). If it fails because there are GUP pins on the page, unmap fails. For now, information about exclusivity is lost. In the future, we might want to remember that information in the swap entry in some cases, however, it requires more thought, care, and a way to store that information in swap entries. I.5. Swapin handling do_swap_page() will never stumble over exclusive anonymous pages in the swap cache, as try_to_migrate() prohibits that. do_swap_page() always has to detect manually if an anonymous page is exclusive and has to set RMAP_EXCLUSIVE for page_add_anon_rmap() accordingly. I.6. THP handling __split_huge_pmd_locked() has to move the information about exclusivity from the PMD to the PTEs. a) In case we have a readable-exclusive PMD migration entry, simply insert readable-exclusive PTE migration entries. b) In case we have a present PMD entry and we don't want to freeze ("convert to migration entries"), simply forward PG_anon_exclusive to all sub-pages, no need to temporarily clear the bit. c) In case we have a present PMD entry and want to freeze, handle it similar to try_to_migrate(): try marking the page shared first. In case we fail, we ignore the "freeze" instruction and simply split ordinarily. try_to_migrate() will properly fail because the THP is still mapped via PTEs. When splitting a compound anonymous folio (THP), the information about exclusivity is implicitly handled via the migration entries: no need to replicate PG_anon_exclusive manually. I.7. fork() handling fork() handling is relatively easy, because PG_anon_exclusive is only expressive for some page table entry types. a) Present anonymous pages page_try_dup_anon_rmap() will mark the given subpage shared -- which will fail if the page is pinned. If it failed, we have to copy (or PTE-map a PMD to handle it on the PTE level). Note that device exclusive entries are just a pointer at a PageAnon() page. fork() will first convert a device exclusive entry to a present page table and handle it just like present anonymous pages. b) Device private entry Device private entries point at PageAnon() pages that cannot be mapped directly and, therefore, cannot get pinned. page_try_dup_anon_rmap() will mark the given subpage shared, which cannot fail because they cannot get pinned. c) HW poison entries PG_anon_exclusive will remain untouched and is stale -- the page table entry is just a placeholder after all. d) Migration entries Writable and readable-exclusive entries are converted to readable entries: possibly shared. I.8. mprotect() handling mprotect() only has to properly handle the new readable-exclusive migration entry: When write-protecting a migration entry that points at an anonymous page, remember the information about exclusivity via the "readable-exclusive" migration entry type. II. Migration and GUP-fast Whenever replacing a present page table entry that maps an exclusive anonymous page by a migration entry, we have to mark the page possibly shared and synchronize against GUP-fast by a proper clear/invalidate+flush to make the following scenario impossible: 1. try_to_migrate() places a migration entry after checking for GUP pins and marks the page possibly shared. 2. GUP-fast pins the page due to lack of synchronization 3. fork() converts the "writable/readable-exclusive" migration entry into a readable migration entry 4. Migration fails due to the GUP pin (failing to freeze the refcount) 5. Migration entries are restored. PG_anon_exclusive is lost -> We have a pinned page that is not marked exclusive anymore. Note that we move information about exclusivity from the page to the migration entry as it otherwise highly overcomplicates fork() and PTE-mapping a THP. III. Swapout and GUP-fast Whenever replacing a present page table entry that maps an exclusive anonymous page by a swap entry, we have to mark the page possibly shared and synchronize against GUP-fast by a proper clear/invalidate+flush to make the following scenario impossible: 1. try_to_unmap() places a swap entry after checking for GUP pins and clears exclusivity information on the page. 2. GUP-fast pins the page due to lack of synchronization. -> We have a pinned page that is not marked exclusive anymore. If we'd ever store information about exclusivity in the swap entry, similar to migration handling, the same considerations as in II would apply. This is future work. Link: https://lkml.kernel.org/r/20220428083441.37290-13-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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a1a3a2fc30 |
memory tiering: skip to scan fast memory
If the NUMA balancing isn't used to optimize the page placement among sockets but only among memory types, the hot pages in the fast memory node couldn't be migrated (promoted) to anywhere. So it's unnecessary to scan the pages in the fast memory node via changing their PTE/PMD mapping to be PROT_NONE. So that the page faults could be avoided too. In the test, if only the memory tiering NUMA balancing mode is enabled, the number of the NUMA balancing hint faults for the DRAM node is reduced to almost 0 with the patch. While the benchmark score doesn't change visibly. Link: https://lkml.kernel.org/r/20220221084529.1052339-4-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Suggested-by: Dave Hansen <dave.hansen@linux.intel.com> Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Yang Shi <shy828301@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Rik van Riel <riel@surriel.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Zi Yan <ziy@nvidia.com> Cc: Wei Xu <weixugc@google.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: zhongjiang-ali <zhongjiang-ali@linux.alibaba.com> Cc: Feng Tang <feng.tang@intel.com> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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5c26f6ac94 |
mm: refactor vm_area_struct::anon_vma_name usage code
Avoid mixing strings and their anon_vma_name referenced pointers by using struct anon_vma_name whenever possible. This simplifies the code and allows easier sharing of anon_vma_name structures when they represent the same name. [surenb@google.com: fix comment] Link: https://lkml.kernel.org/r/20220223153613.835563-1-surenb@google.com Link: https://lkml.kernel.org/r/20220224231834.1481408-1-surenb@google.com Signed-off-by: Suren Baghdasaryan <surenb@google.com> Suggested-by: Matthew Wilcox <willy@infradead.org> Suggested-by: Michal Hocko <mhocko@suse.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Colin Cross <ccross@google.com> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Kees Cook <keescook@chromium.org> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Christian Brauner <brauner@kernel.org> Cc: Alexey Gladkov <legion@kernel.org> Cc: Sasha Levin <sashal@kernel.org> Cc: Chris Hyser <chris.hyser@oracle.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Peter Collingbourne <pcc@google.com> Cc: Xiaofeng Cao <caoxiaofeng@yulong.com> Cc: David Hildenbrand <david@redhat.com> Cc: Cyrill Gorcunov <gorcunov@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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80d47f5de5 |
mm: don't try to NUMA-migrate COW pages that have other uses
Oded Gabbay reports that enabling NUMA balancing causes corruption with his Gaudi accelerator test load: "All the details are in the bug, but the bottom line is that somehow, this patch causes corruption when the numa balancing feature is enabled AND we don't use process affinity AND we use GUP to pin pages so our accelerator can DMA to/from system memory. Either disabling numa balancing, using process affinity to bind to specific numa-node or reverting this patch causes the bug to disappear" and Oded bisected the issue to commit |
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9a10064f56 |
mm: add a field to store names for private anonymous memory
In many userspace applications, and especially in VM based applications like Android uses heavily, there are multiple different allocators in use. At a minimum there is libc malloc and the stack, and in many cases there are libc malloc, the stack, direct syscalls to mmap anonymous memory, and multiple VM heaps (one for small objects, one for big objects, etc.). Each of these layers usually has its own tools to inspect its usage; malloc by compiling a debug version, the VM through heap inspection tools, and for direct syscalls there is usually no way to track them. On Android we heavily use a set of tools that use an extended version of the logic covered in Documentation/vm/pagemap.txt to walk all pages mapped in userspace and slice their usage by process, shared (COW) vs. unique mappings, backing, etc. This can account for real physical memory usage even in cases like fork without exec (which Android uses heavily to share as many private COW pages as possible between processes), Kernel SamePage Merging, and clean zero pages. It produces a measurement of the pages that only exist in that process (USS, for unique), and a measurement of the physical memory usage of that process with the cost of shared pages being evenly split between processes that share them (PSS). If all anonymous memory is indistinguishable then figuring out the real physical memory usage (PSS) of each heap requires either a pagemap walking tool that can understand the heap debugging of every layer, or for every layer's heap debugging tools to implement the pagemap walking logic, in which case it is hard to get a consistent view of memory across the whole system. Tracking the information in userspace leads to all sorts of problems. It either needs to be stored inside the process, which means every process has to have an API to export its current heap information upon request, or it has to be stored externally in a filesystem that somebody needs to clean up on crashes. It needs to be readable while the process is still running, so it has to have some sort of synchronization with every layer of userspace. Efficiently tracking the ranges requires reimplementing something like the kernel vma trees, and linking to it from every layer of userspace. It requires more memory, more syscalls, more runtime cost, and more complexity to separately track regions that the kernel is already tracking. This patch adds a field to /proc/pid/maps and /proc/pid/smaps to show a userspace-provided name for anonymous vmas. The names of named anonymous vmas are shown in /proc/pid/maps and /proc/pid/smaps as [anon:<name>]. Userspace can set the name for a region of memory by calling prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, start, len, (unsigned long)name) Setting the name to NULL clears it. The name length limit is 80 bytes including NUL-terminator and is checked to contain only printable ascii characters (including space), except '[',']','\','$' and '`'. Ascii strings are being used to have a descriptive identifiers for vmas, which can be understood by the users reading /proc/pid/maps or /proc/pid/smaps. Names can be standardized for a given system and they can include some variable parts such as the name of the allocator or a library, tid of the thread using it, etc. The name is stored in a pointer in the shared union in vm_area_struct that points to a null terminated string. Anonymous vmas with the same name (equivalent strings) and are otherwise mergeable will be merged. The name pointers are not shared between vmas even if they contain the same name. The name pointer is stored in a union with fields that are only used on file-backed mappings, so it does not increase memory usage. CONFIG_ANON_VMA_NAME kernel configuration is introduced to enable this feature. It keeps the feature disabled by default to prevent any additional memory overhead and to avoid confusing procfs parsers on systems which are not ready to support named anonymous vmas. The patch is based on the original patch developed by Colin Cross, more specifically on its latest version [1] posted upstream by Sumit Semwal. It used a userspace pointer to store vma names. In that design, name pointers could be shared between vmas. However during the last upstreaming attempt, Kees Cook raised concerns [2] about this approach and suggested to copy the name into kernel memory space, perform validity checks [3] and store as a string referenced from vm_area_struct. One big concern is about fork() performance which would need to strdup anonymous vma names. Dave Hansen suggested experimenting with worst-case scenario of forking a process with 64k vmas having longest possible names [4]. I ran this experiment on an ARM64 Android device and recorded a worst-case regression of almost 40% when forking such a process. This regression is addressed in the followup patch which replaces the pointer to a name with a refcounted structure that allows sharing the name pointer between vmas of the same name. Instead of duplicating the string during fork() or when splitting a vma it increments the refcount. [1] https://lore.kernel.org/linux-mm/20200901161459.11772-4-sumit.semwal@linaro.org/ [2] https://lore.kernel.org/linux-mm/202009031031.D32EF57ED@keescook/ [3] https://lore.kernel.org/linux-mm/202009031022.3834F692@keescook/ [4] https://lore.kernel.org/linux-mm/5d0358ab-8c47-2f5f-8e43-23b89d6a8e95@intel.com/ Changes for prctl(2) manual page (in the options section): PR_SET_VMA Sets an attribute specified in arg2 for virtual memory areas starting from the address specified in arg3 and spanning the size specified in arg4. arg5 specifies the value of the attribute to be set. Note that assigning an attribute to a virtual memory area might prevent it from being merged with adjacent virtual memory areas due to the difference in that attribute's value. Currently, arg2 must be one of: PR_SET_VMA_ANON_NAME Set a name for anonymous virtual memory areas. arg5 should be a pointer to a null-terminated string containing the name. The name length including null byte cannot exceed 80 bytes. If arg5 is NULL, the name of the appropriate anonymous virtual memory areas will be reset. The name can contain only printable ascii characters (including space), except '[',']','\','$' and '`'. This feature is available only if the kernel is built with the CONFIG_ANON_VMA_NAME option enabled. [surenb@google.com: docs: proc.rst: /proc/PID/maps: fix malformed table] Link: https://lkml.kernel.org/r/20211123185928.2513763-1-surenb@google.com [surenb: rebased over v5.15-rc6, replaced userpointer with a kernel copy, added input sanitization and CONFIG_ANON_VMA_NAME config. The bulk of the work here was done by Colin Cross, therefore, with his permission, keeping him as the author] Link: https://lkml.kernel.org/r/20211019215511.3771969-2-surenb@google.com Signed-off-by: Colin Cross <ccross@google.com> Signed-off-by: Suren Baghdasaryan <surenb@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: David Rientjes <rientjes@google.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jan Glauber <jan.glauber@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: John Stultz <john.stultz@linaro.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rob Landley <rob@landley.net> Cc: "Serge E. Hallyn" <serge.hallyn@ubuntu.com> Cc: Shaohua Li <shli@fusionio.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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6af5fa0dc7 |
mm/mprotect.c: avoid repeated assignment in do_mprotect_pkey()
After adjustment, the repeated assignment of "prev" is avoided, and the readability of the code is improved. Link: https://lkml.kernel.org/r/20211012152444.4127-1-fishland@aliyun.com Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Liu Song <liu.song11@zte.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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b756a3b5e7 |
mm: device exclusive memory access
Some devices require exclusive write access to shared virtual memory (SVM) ranges to perform atomic operations on that memory. This requires CPU page tables to be updated to deny access whilst atomic operations are occurring. In order to do this introduce a new swap entry type (SWP_DEVICE_EXCLUSIVE). When a SVM range needs to be marked for exclusive access by a device all page table mappings for the particular range are replaced with device exclusive swap entries. This causes any CPU access to the page to result in a fault. Faults are resovled by replacing the faulting entry with the original mapping. This results in MMU notifiers being called which a driver uses to update access permissions such as revoking atomic access. After notifiers have been called the device will no longer have exclusive access to the region. Walking of the page tables to find the target pages is handled by get_user_pages() rather than a direct page table walk. A direct page table walk similar to what migrate_vma_collect()/unmap() does could also have been utilised. However this resulted in more code similar in functionality to what get_user_pages() provides as page faulting is required to make the PTEs present and to break COW. [dan.carpenter@oracle.com: fix signedness bug in make_device_exclusive_range()] Link: https://lkml.kernel.org/r/YNIz5NVnZ5GiZ3u1@mwanda Link: https://lkml.kernel.org/r/20210616105937.23201-8-apopple@nvidia.com Signed-off-by: Alistair Popple <apopple@nvidia.com> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Ben Skeggs <bskeggs@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Peter Xu <peterx@redhat.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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4dd845b5a3 |
mm/swapops: rework swap entry manipulation code
Both migration and device private pages use special swap entries that are manipluated by a range of inline functions. The arguments to these are somewhat inconsistent so rework them to remove flag type arguments and to make the arguments similar for both read and write entry creation. Link: https://lkml.kernel.org/r/20210616105937.23201-3-apopple@nvidia.com Signed-off-by: Alistair Popple <apopple@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Cc: Ben Skeggs <bskeggs@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Peter Xu <peterx@redhat.com> Cc: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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f0953a1bba |
mm: fix typos in comments
Fix ~94 single-word typos in locking code comments, plus a few very obvious grammar mistakes. Link: https://lkml.kernel.org/r/20210322212624.GA1963421@gmail.com Link: https://lore.kernel.org/r/20210322205203.GB1959563@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Cc: Bhaskar Chowdhury <unixbhaskar@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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dbf53f7597 |
mm/mprotect.c: optimize error detection in do_mprotect_pkey()
Obviously, the error variable detection of the if statement is for the mprotect callback function, so it is also put into the scope of calling callbck. This is a cleanup which makes this site consistent with the rest of this function's error handling. Link: https://lkml.kernel.org/r/20210118133310.98375-1-tianjia.zhang@linux.alibaba.com Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com> Reported-by: Jia Zhang <zhang.jia@linux.alibaba.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Jarkko Sakkinen <jarkko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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95bb7c42ac |
mm: Add 'mprotect' hook to struct vm_operations_struct
Background ========== 1. SGX enclave pages are populated with data by copying from normal memory via ioctl() (SGX_IOC_ENCLAVE_ADD_PAGES), which will be added later in this series. 2. It is desirable to be able to restrict those normal memory data sources. For instance, to ensure that the source data is executable before copying data to an executable enclave page. 3. Enclave page permissions are dynamic (just like normal permissions) and can be adjusted at runtime with mprotect(). This creates a problem because the original data source may have long since vanished at the time when enclave page permissions are established (mmap() or mprotect()). The solution (elsewhere in this series) is to force enclave creators to declare their paging permission *intent* up front to the ioctl(). This intent can be immediately compared to the source data’s mapping and rejected if necessary. The “intent” is also stashed off for later comparison with enclave PTEs. This ensures that any future mmap()/mprotect() operations performed by the enclave creator or done on behalf of the enclave can be compared with the earlier declared permissions. Problem ======= There is an existing mmap() hook which allows SGX to perform this permission comparison at mmap() time. However, there is no corresponding ->mprotect() hook. Solution ======== Add a vm_ops->mprotect() hook so that mprotect() operations which are inconsistent with any page's stashed intent can be rejected by the driver. Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> Co-developed-by: Jarkko Sakkinen <jarkko@kernel.org> Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Jethro Beekman <jethro@fortanix.com> Acked-by: Dave Hansen <dave.hansen@intel.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Hillf Danton <hdanton@sina.com> Cc: linux-mm@kvack.org Link: https://lkml.kernel.org/r/20201112220135.165028-11-jarkko@kernel.org |
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c462ac288f |
mm: Introduce arch_validate_flags()
Similarly to arch_validate_prot() called from do_mprotect_pkey(), an architecture may need to sanity-check the new vm_flags. Define a dummy function always returning true. In addition to do_mprotect_pkey(), also invoke it from mmap_region() prior to updating vma->vm_page_prot to allow the architecture code to veto potentially inconsistent vm_flags. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> |
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c1e8d7c6a7 |
mmap locking API: convert mmap_sem comments
Convert comments that reference mmap_sem to reference mmap_lock instead. [akpm@linux-foundation.org: fix up linux-next leftovers] [akpm@linux-foundation.org: s/lockaphore/lock/, per Vlastimil] [akpm@linux-foundation.org: more linux-next fixups, per Michel] Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ying Han <yinghan@google.com> Link: http://lkml.kernel.org/r/20200520052908.204642-13-walken@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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d8ed45c5dc |
mmap locking API: use coccinelle to convert mmap_sem rwsem call sites
This change converts the existing mmap_sem rwsem calls to use the new mmap locking API instead. The change is generated using coccinelle with the following rule: // spatch --sp-file mmap_lock_api.cocci --in-place --include-headers --dir . @@ expression mm; @@ ( -init_rwsem +mmap_init_lock | -down_write +mmap_write_lock | -down_write_killable +mmap_write_lock_killable | -down_write_trylock +mmap_write_trylock | -up_write +mmap_write_unlock | -downgrade_write +mmap_write_downgrade | -down_read +mmap_read_lock | -down_read_killable +mmap_read_lock_killable | -down_read_trylock +mmap_read_trylock | -up_read +mmap_read_unlock ) -(&mm->mmap_sem) +(mm) Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ying Han <yinghan@google.com> Link: http://lkml.kernel.org/r/20200520052908.204642-5-walken@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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ca5999fde0 |
mm: introduce include/linux/pgtable.h
The include/linux/pgtable.h is going to be the home of generic page table manipulation functions. Start with moving asm-generic/pgtable.h to include/linux/pgtable.h and make the latter include asm/pgtable.h. Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Cain <bcain@codeaurora.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chris Zankel <chris@zankel.net> Cc: "David S. Miller" <davem@davemloft.net> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Ungerer <gerg@linux-m68k.org> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Guo Ren <guoren@kernel.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Helge Deller <deller@gmx.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Ley Foon Tan <ley.foon.tan@intel.com> Cc: Mark Salter <msalter@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Nick Hu <nickhu@andestech.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: Vincent Chen <deanbo422@gmail.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Will Deacon <will@kernel.org> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Link: http://lkml.kernel.org/r/20200514170327.31389-3-rppt@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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6cb4d9a287 |
mm/vma: introduce VM_ACCESS_FLAGS
There are many places where all basic VMA access flags (read, write, exec) are initialized or checked against as a group. One such example is during page fault. Existing vma_is_accessible() wrapper already creates the notion of VMA accessibility as a group access permissions. Hence lets just create VM_ACCESS_FLAGS (VM_READ|VM_WRITE|VM_EXEC) which will not only reduce code duplication but also extend the VMA accessibility concept in general. Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Cc: Russell King <linux@armlinux.org.uk> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Mark Salter <msalter@redhat.com> Cc: Nick Hu <nickhu@andestech.com> Cc: Ley Foon Tan <ley.foon.tan@intel.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Rob Springer <rspringer@google.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Link: http://lkml.kernel.org/r/1583391014-8170-3-git-send-email-anshuman.khandual@arm.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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f45ec5ff16 |
userfaultfd: wp: support swap and page migration
For either swap and page migration, we all use the bit 2 of the entry to identify whether this entry is uffd write-protected. It plays a similar role as the existing soft dirty bit in swap entries but only for keeping the uffd-wp tracking for a specific PTE/PMD. Something special here is that when we want to recover the uffd-wp bit from a swap/migration entry to the PTE bit we'll also need to take care of the _PAGE_RW bit and make sure it's cleared, otherwise even with the _PAGE_UFFD_WP bit we can't trap it at all. In change_pte_range() we do nothing for uffd if the PTE is a swap entry. That can lead to data mismatch if the page that we are going to write protect is swapped out when sending the UFFDIO_WRITEPROTECT. This patch also applies/removes the uffd-wp bit even for the swap entries. Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Bobby Powers <bobbypowers@gmail.com> Cc: Brian Geffon <bgeffon@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Denis Plotnikov <dplotnikov@virtuozzo.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Martin Cracauer <cracauer@cons.org> Cc: Marty McFadden <mcfadden8@llnl.gov> Cc: Maya Gokhale <gokhale2@llnl.gov> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@fb.com> Link: http://lkml.kernel.org/r/20200220163112.11409-11-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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292924b260 |
userfaultfd: wp: apply _PAGE_UFFD_WP bit
Firstly, introduce two new flags MM_CP_UFFD_WP[_RESOLVE] for change_protection() when used with uffd-wp and make sure the two new flags are exclusively used. Then, - For MM_CP_UFFD_WP: apply the _PAGE_UFFD_WP bit and remove _PAGE_RW when a range of memory is write protected by uffd - For MM_CP_UFFD_WP_RESOLVE: remove the _PAGE_UFFD_WP bit and recover _PAGE_RW when write protection is resolved from userspace And use this new interface in mwriteprotect_range() to replace the old MM_CP_DIRTY_ACCT. Do this change for both PTEs and huge PMDs. Then we can start to identify which PTE/PMD is write protected by general (e.g., COW or soft dirty tracking), and which is for userfaultfd-wp. Since we should keep the _PAGE_UFFD_WP when doing pte_modify(), add it into _PAGE_CHG_MASK as well. Meanwhile, since we have this new bit, we can be even more strict when detecting uffd-wp page faults in either do_wp_page() or wp_huge_pmd(). After we're with _PAGE_UFFD_WP, a special case is when a page is both protected by the general COW logic and also userfault-wp. Here the userfault-wp will have higher priority and will be handled first. Only after the uffd-wp bit is cleared on the PTE/PMD will we continue to handle the general COW. These are the steps on what will happen with such a page: 1. CPU accesses write protected shared page (so both protected by general COW and uffd-wp), blocked by uffd-wp first because in do_wp_page we'll handle uffd-wp first, so it has higher priority than general COW. 2. Uffd service thread receives the request, do UFFDIO_WRITEPROTECT to remove the uffd-wp bit upon the PTE/PMD. However here we still keep the write bit cleared. Notify the blocked CPU. 3. The blocked CPU resumes the page fault process with a fault retry, during retry it'll notice it was not with the uffd-wp bit this time but it is still write protected by general COW, then it'll go though the COW path in the fault handler, copy the page, apply write bit where necessary, and retry again. 4. The CPU will be able to access this page with write bit set. Suggested-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Brian Geffon <bgeffon@google.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: Martin Cracauer <cracauer@cons.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Bobby Powers <bobbypowers@gmail.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Maya Gokhale <gokhale2@llnl.gov> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Marty McFadden <mcfadden8@llnl.gov> Cc: Denis Plotnikov <dplotnikov@virtuozzo.com> Cc: Hugh Dickins <hughd@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@fb.com> Link: http://lkml.kernel.org/r/20200220163112.11409-8-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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58705444c4 |
mm: merge parameters for change_protection()
change_protection() was used by either the NUMA or mprotect() code, there's one parameter for each of the callers (dirty_accountable and prot_numa). Further, these parameters are passed along the calls: - change_protection_range() - change_p4d_range() - change_pud_range() - change_pmd_range() - ... Now we introduce a flag for change_protect() and all these helpers to replace these parameters. Then we can avoid passing multiple parameters multiple times along the way. More importantly, it'll greatly simplify the work if we want to introduce any new parameters to change_protection(). In the follow up patches, a new parameter for userfaultfd write protection will be introduced. No functional change at all. Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Jerome Glisse <jglisse@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Bobby Powers <bobbypowers@gmail.com> Cc: Brian Geffon <bgeffon@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Denis Plotnikov <dplotnikov@virtuozzo.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Martin Cracauer <cracauer@cons.org> Cc: Marty McFadden <mcfadden8@llnl.gov> Cc: Maya Gokhale <gokhale2@llnl.gov> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@fb.com> Link: http://lkml.kernel.org/r/20200220163112.11409-7-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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9de4f22a60 |
mm: code cleanup for MADV_FREE
Some comments for MADV_FREE is revised and added to help people understand the MADV_FREE code, especially the page flag, PG_swapbacked. This makes page_is_file_cache() isn't consistent with its comments. So the function is renamed to page_is_file_lru() to make them consistent again. All these are put in one patch as one logical change. Suggested-by: David Hildenbrand <david@redhat.com> Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: David Rientjes <rientjes@google.com> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@kernel.org> Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/20200317100342.2730705-1-ying.huang@intel.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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8b272b3cbb |
mm, numa: fix bad pmd by atomically check for pmd_trans_huge when marking page tables prot_numa
: A user reported a bug against a distribution kernel while running a : proprietary workload described as "memory intensive that is not swapping" : that is expected to apply to mainline kernels. The workload is : read/write/modifying ranges of memory and checking the contents. They : reported that within a few hours that a bad PMD would be reported followed : by a memory corruption where expected data was all zeros. A partial : report of the bad PMD looked like : : [ 5195.338482] ../mm/pgtable-generic.c:33: bad pmd ffff8888157ba008(000002e0396009e2) : [ 5195.341184] ------------[ cut here ]------------ : [ 5195.356880] kernel BUG at ../mm/pgtable-generic.c:35! : .... : [ 5195.410033] Call Trace: : [ 5195.410471] [<ffffffff811bc75d>] change_protection_range+0x7dd/0x930 : [ 5195.410716] [<ffffffff811d4be8>] change_prot_numa+0x18/0x30 : [ 5195.410918] [<ffffffff810adefe>] task_numa_work+0x1fe/0x310 : [ 5195.411200] [<ffffffff81098322>] task_work_run+0x72/0x90 : [ 5195.411246] [<ffffffff81077139>] exit_to_usermode_loop+0x91/0xc2 : [ 5195.411494] [<ffffffff81003a51>] prepare_exit_to_usermode+0x31/0x40 : [ 5195.411739] [<ffffffff815e56af>] retint_user+0x8/0x10 : : Decoding revealed that the PMD was a valid prot_numa PMD and the bad PMD : was a false detection. The bug does not trigger if automatic NUMA : balancing or transparent huge pages is disabled. : : The bug is due a race in change_pmd_range between a pmd_trans_huge and : pmd_nond_or_clear_bad check without any locks held. During the : pmd_trans_huge check, a parallel protection update under lock can have : cleared the PMD and filled it with a prot_numa entry between the transhuge : check and the pmd_none_or_clear_bad check. : : While this could be fixed with heavy locking, it's only necessary to make : a copy of the PMD on the stack during change_pmd_range and avoid races. A : new helper is created for this as the check if quite subtle and the : existing similar helpful is not suitable. This passed 154 hours of : testing (usually triggers between 20 minutes and 24 hours) without : detecting bad PMDs or corruption. A basic test of an autonuma-intensive : workload showed no significant change in behaviour. Although Mel withdrew the patch on the face of LKML comment https://lkml.org/lkml/2017/4/10/922 the race window aforementioned is still open, and we have reports of Linpack test reporting bad residuals after the bad PMD warning is observed. In addition to that, bad rss-counter and non-zero pgtables assertions are triggered on mm teardown for the task hitting the bad PMD. host kernel: mm/pgtable-generic.c:40: bad pmd 00000000b3152f68(8000000d2d2008e7) .... host kernel: BUG: Bad rss-counter state mm:00000000b583043d idx:1 val:512 host kernel: BUG: non-zero pgtables_bytes on freeing mm: 4096 The issue is observed on a v4.18-based distribution kernel, but the race window is expected to be applicable to mainline kernels, as well. [akpm@linux-foundation.org: fix comment typo, per Rafael] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Rafael Aquini <aquini@redhat.com> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Cc: <stable@vger.kernel.org> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@suse.com> Link: http://lkml.kernel.org/r/20200216191800.22423-1-aquini@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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a818f5363a |
autonuma: reduce cache footprint when scanning page tables
In auto NUMA balancing page table scanning, if the pte_protnone() is true, the PTE needs not to be changed because it's in target state already. So other checking on corresponding struct page is unnecessary too. So, if we check pte_protnone() firstly for each PTE, we can avoid unnecessary struct page accessing, so that reduce the cache footprint of NUMA balancing page table scanning. In the performance test of pmbench memory accessing benchmark with 80:20 read/write ratio and normal access address distribution on a 2 socket Intel server with Optance DC Persistent Memory, perf profiling shows that the autonuma page table scanning time reduces from 1.23% to 0.97% (that is, reduced 21%) with the patch. Link: http://lkml.kernel.org/r/20191101075727.26683-3-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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057d338910 |
mm: untag user pointers passed to memory syscalls
This patch is a part of a series that extends kernel ABI to allow to pass tagged user pointers (with the top byte set to something else other than 0x00) as syscall arguments. This patch allows tagged pointers to be passed to the following memory syscalls: get_mempolicy, madvise, mbind, mincore, mlock, mlock2, mprotect, mremap, msync, munlock, move_pages. The mmap and mremap syscalls do not currently accept tagged addresses. Architectures may interpret the tag as a background colour for the corresponding vma. Link: http://lkml.kernel.org/r/aaf0c0969d46b2feb9017f3e1b3ef3970b633d91.1563904656.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com> Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Eric Auger <eric.auger@redhat.com> Cc: Felix Kuehling <Felix.Kuehling@amd.com> Cc: Jens Wiklander <jens.wiklander@linaro.org> Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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7b86ac3371 |
pagewalk: separate function pointers from iterator data
The mm_walk structure currently mixed data and code. Split out the operations vectors into a new mm_walk_ops structure, and while we are changing the API also declare the mm_walk structure inside the walk_page_range and walk_page_vma functions. Based on patch from Linus Torvalds. Link: https://lore.kernel.org/r/20190828141955.22210-3-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com> Reviewed-by: Steven Price <steven.price@arm.com> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com> |
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a520110e4a |
mm: split out a new pagewalk.h header from mm.h
Add a new header for the two handful of users of the walk_page_range / walk_page_vma interface instead of polluting all users of mm.h with it. Link: https://lore.kernel.org/r/20190828141955.22210-2-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com> Reviewed-by: Steven Price <steven.price@arm.com> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com> |
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94393c7896 |
mm/mprotect.c: fix compilation warning because of unused 'mm' variable
Since
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7269f99993 |
mm/mmu_notifier: use correct mmu_notifier events for each invalidation
This updates each existing invalidation to use the correct mmu notifier event that represent what is happening to the CPU page table. See the patch which introduced the events to see the rational behind this. Link: http://lkml.kernel.org/r/20190326164747.24405-7-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Cc: Christian König <christian.koenig@amd.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Peter Xu <peterx@redhat.com> Cc: Felix Kuehling <Felix.Kuehling@amd.com> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Ross Zwisler <zwisler@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krcmar <rkrcmar@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Christian Koenig <christian.koenig@amd.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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6f4f13e8d9 |
mm/mmu_notifier: contextual information for event triggering invalidation
CPU page table update can happens for many reasons, not only as a result of a syscall (munmap(), mprotect(), mremap(), madvise(), ...) but also as a result of kernel activities (memory compression, reclaim, migration, ...). Users of mmu notifier API track changes to the CPU page table and take specific action for them. While current API only provide range of virtual address affected by the change, not why the changes is happening. This patchset do the initial mechanical convertion of all the places that calls mmu_notifier_range_init to also provide the default MMU_NOTIFY_UNMAP event as well as the vma if it is know (most invalidation happens against a given vma). Passing down the vma allows the users of mmu notifier to inspect the new vma page protection. The MMU_NOTIFY_UNMAP is always the safe default as users of mmu notifier should assume that every for the range is going away when that event happens. A latter patch do convert mm call path to use a more appropriate events for each call. This is done as 2 patches so that no call site is forgotten especialy as it uses this following coccinelle patch: %<---------------------------------------------------------------------- @@ identifier I1, I2, I3, I4; @@ static inline void mmu_notifier_range_init(struct mmu_notifier_range *I1, +enum mmu_notifier_event event, +unsigned flags, +struct vm_area_struct *vma, struct mm_struct *I2, unsigned long I3, unsigned long I4) { ... } @@ @@ -#define mmu_notifier_range_init(range, mm, start, end) +#define mmu_notifier_range_init(range, event, flags, vma, mm, start, end) @@ expression E1, E3, E4; identifier I1; @@ <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, I1, I1->vm_mm, E3, E4) ...> @@ expression E1, E2, E3, E4; identifier FN, VMA; @@ FN(..., struct vm_area_struct *VMA, ...) { <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, VMA, E2, E3, E4) ...> } @@ expression E1, E2, E3, E4; identifier FN, VMA; @@ FN(...) { struct vm_area_struct *VMA; <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, VMA, E2, E3, E4) ...> } @@ expression E1, E2, E3, E4; identifier FN; @@ FN(...) { <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, NULL, E2, E3, E4) ...> } ---------------------------------------------------------------------->% Applied with: spatch --all-includes --sp-file mmu-notifier.spatch fs/proc/task_mmu.c --in-place spatch --sp-file mmu-notifier.spatch --dir kernel/events/ --in-place spatch --sp-file mmu-notifier.spatch --dir mm --in-place Link: http://lkml.kernel.org/r/20190326164747.24405-6-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Cc: Christian König <christian.koenig@amd.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Peter Xu <peterx@redhat.com> Cc: Felix Kuehling <Felix.Kuehling@amd.com> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Ross Zwisler <zwisler@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krcmar <rkrcmar@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Christian Koenig <christian.koenig@amd.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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04a8645304 |
mm: update ptep_modify_prot_commit to take old pte value as arg
Architectures like ppc64 require to do a conditional tlb flush based on the old and new value of pte. Enable that by passing old pte value as the arg. Link: http://lkml.kernel.org/r/20190116085035.29729-3-aneesh.kumar@linux.ibm.com Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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0cbe3e26ab |
mm: update ptep_modify_prot_start/commit to take vm_area_struct as arg
Patch series "NestMMU pte upgrade workaround for mprotect", v5.
We can upgrade pte access (R -> RW transition) via mprotect. We need to
make sure we follow the recommended pte update sequence as outlined in
commit
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ac46d4f3c4 |
mm/mmu_notifier: use structure for invalidate_range_start/end calls v2
To avoid having to change many call sites everytime we want to add a parameter use a structure to group all parameters for the mmu_notifier invalidate_range_start/end cakks. No functional changes with this patch. [akpm@linux-foundation.org: coding style fixes] Link: http://lkml.kernel.org/r/20181205053628.3210-3-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Acked-by: Christian König <christian.koenig@amd.com> Acked-by: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Ross Zwisler <zwisler@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krcmar <rkrcmar@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Felix Kuehling <felix.kuehling@amd.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> From: Jérôme Glisse <jglisse@redhat.com> Subject: mm/mmu_notifier: use structure for invalidate_range_start/end calls v3 fix build warning in migrate.c when CONFIG_MMU_NOTIFIER=n Link: http://lkml.kernel.org/r/20181213171330.8489-3-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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42e4089c78 |
x86/speculation/l1tf: Disallow non privileged high MMIO PROT_NONE mappings
For L1TF PROT_NONE mappings are protected by inverting the PFN in the page table entry. This sets the high bits in the CPU's address space, thus making sure to point to not point an unmapped entry to valid cached memory. Some server system BIOSes put the MMIO mappings high up in the physical address space. If such an high mapping was mapped to unprivileged users they could attack low memory by setting such a mapping to PROT_NONE. This could happen through a special device driver which is not access protected. Normal /dev/mem is of course access protected. To avoid this forbid PROT_NONE mappings or mprotect for high MMIO mappings. Valid page mappings are allowed because the system is then unsafe anyways. It's not expected that users commonly use PROT_NONE on MMIO. But to minimize any impact this is only enforced if the mapping actually refers to a high MMIO address (defined as the MAX_PA-1 bit being set), and also skip the check for root. For mmaps this is straight forward and can be handled in vm_insert_pfn and in remap_pfn_range(). For mprotect it's a bit trickier. At the point where the actual PTEs are accessed a lot of state has been changed and it would be difficult to undo on an error. Since this is a uncommon case use a separate early page talk walk pass for MMIO PROT_NONE mappings that checks for this condition early. For non MMIO and non PROT_NONE there are no changes. Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Dave Hansen <dave.hansen@intel.com> |
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09a913a7a9 |
sched/numa: avoid trapping faults and attempting migration of file-backed dirty pages
change_pte_range is called from task work context to mark PTEs for receiving NUMA faulting hints. If the marked pages are dirty then migration may fail. Some filesystems cannot migrate dirty pages without blocking so are skipped in MIGRATE_ASYNC mode which just wastes CPU. Even when they can, it can be a waste of cycles when the pages are shared forcing higher scan rates. This patch avoids marking shared dirty pages for hinting faults but also will skip a migration if the page was dirtied after the scanner updated a clean page. This is most noticeable running the NASA Parallel Benchmark when backed by btrfs, the default root filesystem for some distributions, but also noticeable when using XFS. The following are results from a 4-socket machine running a 4.16-rc4 kernel with some scheduler patches that are pending for the next merge window. 4.16.0-rc4 4.16.0-rc4 schedtip-20180309 nodirty-v1 Time cg.D 459.07 ( 0.00%) 444.21 ( 3.24%) Time ep.D 76.96 ( 0.00%) 77.69 ( -0.95%) Time is.D 25.55 ( 0.00%) 27.85 ( -9.00%) Time lu.D 601.58 ( 0.00%) 596.87 ( 0.78%) Time mg.D 107.73 ( 0.00%) 108.22 ( -0.45%) is.D regresses slightly in terms of absolute time but note that that particular load varies quite a bit from run to run. The more relevant observation is the total system CPU usage. 4.16.0-rc4 4.16.0-rc4 schedtip-20180309 nodirty-v1 User 71471.91 70627.04 System 11078.96 8256.13 Elapsed 661.66 632.74 That is a substantial drop in system CPU usage and overall the workload completes faster. The NUMA balancing statistics are also interesting NUMA base PTE updates 111407972 139848884 NUMA huge PMD updates 206506 264869 NUMA page range updates 217139044 275461812 NUMA hint faults 4300924 3719784 NUMA hint local faults 3012539 3416618 NUMA hint local percent 70 91 NUMA pages migrated 1517487 1358420 While more PTEs are scanned due to changes in what faults are gathered, it's clear that a far higher percentage of faults are local as the bulk of the remote hits were dirty pages that, in this case with btrfs, had no chance of migrating. The following is a comparison when using XFS as that is a more realistic filesystem choice for a data partition 4.16.0-rc4 4.16.0-rc4 schedtip-20180309 nodirty-v1r47 Time cg.D 485.28 ( 0.00%) 442.62 ( 8.79%) Time ep.D 77.68 ( 0.00%) 77.54 ( 0.18%) Time is.D 26.44 ( 0.00%) 24.79 ( 6.24%) Time lu.D 597.46 ( 0.00%) 597.11 ( 0.06%) Time mg.D 142.65 ( 0.00%) 105.83 ( 25.81%) That is a reasonable gain on two relatively long-lived workloads. While not presented, there is also a substantial drop in system CPu usage and the NUMA balancing stats show similar improvements in locality as btrfs did. Link: http://lkml.kernel.org/r/20180326094334.zserdec62gwmmfqf@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Reviewed-by: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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2c2d57b5e7 |
mm: Clear arch specific VM flags on protection change
When protection bits are changed on a VMA, some of the architecture specific flags should be cleared as well. An examples of this are the PKEY flags on x86. This patch expands the current code that clears PKEY flags for x86, to support similar functionality for other architectures as well. Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com> Cc: Khalid Aziz <khalid@gonehiking.org> Reviewed-by: Anthony Yznaga <anthony.yznaga@oracle.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net> |
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9035cf9a97 |
mm: Add address parameter to arch_validate_prot()
A protection flag may not be valid across entire address space and hence arch_validate_prot() might need the address a protection bit is being set on to ensure it is a valid protection flag. For example, sparc processors support memory corruption detection (as part of ADI feature) flag on memory addresses mapped on to physical RAM but not on PFN mapped pages or addresses mapped on to devices. This patch adds address to the parameters being passed to arch_validate_prot() so protection bits can be validated in the relevant context. Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com> Cc: Khalid Aziz <khalid@gonehiking.org> Reviewed-by: Anthony Yznaga <anthony.yznaga@oracle.com> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net> |
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859d4adc34 |
mm: numa: do not trap faults on shared data section pages.
Workloads consisting of a large number of processes running the same program with a very large shared data segment may experience performance problems when numa balancing attempts to migrate the shared cow pages. This manifests itself with many processes or tasks in TASK_UNINTERRUPTIBLE state waiting for the shared pages to be migrated. The program listed below simulates the conditions with these results when run with 288 processes on a 144 core/8 socket machine. Average throughput Average throughput Average throughput with numa_balancing=0 with numa_balancing=1 with numa_balancing=1 without the patch with the patch --------------------- --------------------- --------------------- 2118782 2021534 2107979 Complex production environments show less variability and fewer poorly performing outliers accompanied with a smaller number of processes waiting on NUMA page migration with this patch applied. In some cases, %iowait drops from 16%-26% to 0. // SPDX-License-Identifier: GPL-2.0 /* * Copyright (c) 2017 Oracle and/or its affiliates. All rights reserved. */ #include <sys/time.h> #include <stdio.h> #include <wait.h> #include <sys/mman.h> int a[1000000] = {13}; int main(int argc, const char **argv) { int n = 0; int i; pid_t pid; int stat; int *count_array; int cpu_count = 288; long total = 0; struct timeval t1, t2 = {(argc > 1 ? atoi(argv[1]) : 10), 0}; if (argc > 2) cpu_count = atoi(argv[2]); count_array = mmap(NULL, cpu_count * sizeof(int), (PROT_READ|PROT_WRITE), (MAP_SHARED|MAP_ANONYMOUS), 0, 0); if (count_array == MAP_FAILED) { perror("mmap:"); return 0; } for (i = 0; i < cpu_count; ++i) { pid = fork(); if (pid <= 0) break; if ((i & 0xf) == 0) usleep(2); } if (pid != 0) { if (i == 0) { perror("fork:"); return 0; } for (;;) { pid = wait(&stat); if (pid < 0) break; } for (i = 0; i < cpu_count; ++i) total += count_array[i]; printf("Total %ld\n", total); munmap(count_array, cpu_count * sizeof(int)); return 0; } gettimeofday(&t1, 0); timeradd(&t1, &t2, &t1); while (timercmp(&t2, &t1, <)) { int b = 0; int j; for (j = 0; j < 1000000; j++) b += a[j]; gettimeofday(&t2, 0); n++; } count_array[i] = n; return 0; } This patch changes change_pte_range() to skip shared copy-on-write pages when called from change_prot_numa(). NOTE: change_prot_numa() is nominally called from task_numa_work() and queue_pages_test_walk(). task_numa_work() is the auto NUMA balancing path, and queue_pages_test_walk() is part of explicit NUMA policy management. However, queue_pages_test_walk() only calls change_prot_numa() when MPOL_MF_LAZY is specified and currently that is not allowed, so change_prot_numa() is only called from auto NUMA balancing. In the case of explicit NUMA policy management, shared pages are not migrated unless MPOL_MF_MOVE_ALL is specified, and MPOL_MF_MOVE_ALL depends on CAP_SYS_NICE. Currently, there is no way to pass information about MPOL_MF_MOVE_ALL to change_pte_range. This will have to be fixed if MPOL_MF_LAZY is enabled and MPOL_MF_MOVE_ALL is to be honored in lazy migration mode. task_numa_work() skips the read-only VMAs of programs and shared libraries. Link: http://lkml.kernel.org/r/1516751617-7369-1-git-send-email-henry.willard@oracle.com Signed-off-by: Henry Willard <henry.willard@oracle.com> Reviewed-by: Håkon Bugge <haakon.bugge@oracle.com> Reviewed-by: Steve Sistare <steven.sistare@oracle.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Kate Stewart <kstewart@linuxfoundation.org> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Cc: Philippe Ombredanne <pombredanne@nexb.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: "Jérôme Glisse" <jglisse@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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4991c09c7c |
mm/mprotect: add a cond_resched() inside change_pmd_range()
While testing on a large CPU system, detected the following RCU stall many times over the span of the workload. This problem is solved by adding a cond_resched() in the change_pmd_range() function. INFO: rcu_sched detected stalls on CPUs/tasks: 154-....: (670 ticks this GP) idle=022/140000000000000/0 softirq=2825/2825 fqs=612 (detected by 955, t=6002 jiffies, g=4486, c=4485, q=90864) Sending NMI from CPU 955 to CPUs 154: NMI backtrace for cpu 154 CPU: 154 PID: 147071 Comm: workload Not tainted 4.15.0-rc3+ #3 NIP: c0000000000b3f64 LR: c0000000000b33d4 CTR: 000000000000aa18 REGS: 00000000a4b0fb44 TRAP: 0501 Not tainted (4.15.0-rc3+) MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE> CR: 22422082 XER: 00000000 CFAR: 00000000006cf8f0 SOFTE: 1 GPR00: 0010000000000000 c00003ef9b1cb8c0 c0000000010cc600 0000000000000000 GPR04: 8e0000018c32b200 40017b3858fd6e00 8e0000018c32b208 40017b3858fd6e00 GPR08: 8e0000018c32b210 40017b3858fd6e00 8e0000018c32b218 40017b3858fd6e00 GPR12: ffffffffffffffff c00000000fb25100 NIP [c0000000000b3f64] plpar_hcall9+0x44/0x7c LR [c0000000000b33d4] pSeries_lpar_flush_hash_range+0x384/0x420 Call Trace: flush_hash_range+0x48/0x100 __flush_tlb_pending+0x44/0xd0 hpte_need_flush+0x408/0x470 change_protection_range+0xaac/0xf10 change_prot_numa+0x30/0xb0 task_numa_work+0x2d0/0x3e0 task_work_run+0x130/0x190 do_notify_resume+0x118/0x120 ret_from_except_lite+0x70/0x74 Instruction dump: 60000000 f8810028 7ca42b78 7cc53378 7ce63b78 7d074378 7d284b78 7d495378 e9410060 e9610068 e9810070 44000022 <7d806378> e9810028 f88c0000 f8ac0008 Link: http://lkml.kernel.org/r/20171214140551.5794-1-khandual@linux.vnet.ibm.com Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com> Suggested-by: Nicholas Piggin <npiggin@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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b24413180f |
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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5042db43cc |
mm/ZONE_DEVICE: new type of ZONE_DEVICE for unaddressable memory
HMM (heterogeneous memory management) need struct page to support migration from system main memory to device memory. Reasons for HMM and migration to device memory is explained with HMM core patch. This patch deals with device memory that is un-addressable memory (ie CPU can not access it). Hence we do not want those struct page to be manage like regular memory. That is why we extend ZONE_DEVICE to support different types of memory. A persistent memory type is define for existing user of ZONE_DEVICE and a new device un-addressable type is added for the un-addressable memory type. There is a clear separation between what is expected from each memory type and existing user of ZONE_DEVICE are un-affected by new requirement and new use of the un-addressable type. All specific code path are protect with test against the memory type. Because memory is un-addressable we use a new special swap type for when a page is migrated to device memory (this reduces the number of maximum swap file). The main two additions beside memory type to ZONE_DEVICE is two callbacks. First one, page_free() is call whenever page refcount reach 1 (which means the page is free as ZONE_DEVICE page never reach a refcount of 0). This allow device driver to manage its memory and associated struct page. The second callback page_fault() happens when there is a CPU access to an address that is back by a device page (which are un-addressable by the CPU). This callback is responsible to migrate the page back to system main memory. Device driver can not block migration back to system memory, HMM make sure that such page can not be pin into device memory. If device is in some error condition and can not migrate memory back then a CPU page fault to device memory should end with SIGBUS. [arnd@arndb.de: fix warning] Link: http://lkml.kernel.org/r/20170823133213.712917-1-arnd@arndb.de Link: http://lkml.kernel.org/r/20170817000548.32038-8-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Dan Williams <dan.j.williams@intel.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: David Nellans <dnellans@nvidia.com> Cc: Evgeny Baskakov <ebaskakov@nvidia.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Mark Hairgrove <mhairgrove@nvidia.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Sherry Cheung <SCheung@nvidia.com> Cc: Subhash Gutti <sgutti@nvidia.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Bob Liu <liubo95@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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84c3fc4e9c |
mm: thp: check pmd migration entry in common path
When THP migration is being used, memory management code needs to handle pmd migration entries properly. This patch uses !pmd_present() or is_swap_pmd() (depending on whether pmd_none() needs separate code or not) to check pmd migration entries at the places where a pmd entry is present. Since pmd-related code uses split_huge_page(), split_huge_pmd(), pmd_trans_huge(), pmd_trans_unstable(), or pmd_none_or_trans_huge_or_clear_bad(), this patch: 1. adds pmd migration entry split code in split_huge_pmd(), 2. takes care of pmd migration entries whenever pmd_trans_huge() is present, 3. makes pmd_none_or_trans_huge_or_clear_bad() pmd migration entry aware. Since split_huge_page() uses split_huge_pmd() and pmd_trans_unstable() is equivalent to pmd_none_or_trans_huge_or_clear_bad(), we do not change them. Until this commit, a pmd entry should be: 1. pointing to a pte page, 2. is_swap_pmd(), 3. pmd_trans_huge(), 4. pmd_devmap(), or 5. pmd_none(). Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: David Nellans <dnellans@nvidia.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Minchan Kim <minchan@kernel.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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16af97dc5a |
mm: migrate: prevent racy access to tlb_flush_pending
Patch series "fixes of TLB batching races", v6.
It turns out that Linux TLB batching mechanism suffers from various
races. Races that are caused due to batching during reclamation were
recently handled by Mel and this patch-set deals with others. The more
fundamental issue is that concurrent updates of the page-tables allow
for TLB flushes to be batched on one core, while another core changes
the page-tables. This other core may assume a PTE change does not
require a flush based on the updated PTE value, while it is unaware that
TLB flushes are still pending.
This behavior affects KSM (which may result in memory corruption) and
MADV_FREE and MADV_DONTNEED (which may result in incorrect behavior). A
proof-of-concept can easily produce the wrong behavior of MADV_DONTNEED.
Memory corruption in KSM is harder to produce in practice, but was
observed by hacking the kernel and adding a delay before flushing and
replacing the KSM page.
Finally, there is also one memory barrier missing, which may affect
architectures with weak memory model.
This patch (of 7):
Setting and clearing mm->tlb_flush_pending can be performed by multiple
threads, since mmap_sem may only be acquired for read in
task_numa_work(). If this happens, tlb_flush_pending might be cleared
while one of the threads still changes PTEs and batches TLB flushes.
This can lead to the same race between migration and
change_protection_range() that led to the introduction of
tlb_flush_pending. The result of this race was data corruption, which
means that this patch also addresses a theoretically possible data
corruption.
An actual data corruption was not observed, yet the race was was
confirmed by adding assertion to check tlb_flush_pending is not set by
two threads, adding artificial latency in change_protection_range() and
using sysctl to reduce kernel.numa_balancing_scan_delay_ms.
Link: http://lkml.kernel.org/r/20170802000818.4760-2-namit@vmware.com
Fixes:
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3ea277194d |
mm, mprotect: flush TLB if potentially racing with a parallel reclaim leaving stale TLB entries
Nadav Amit identified a theoritical race between page reclaim and mprotect due to TLB flushes being batched outside of the PTL being held. He described the race as follows: CPU0 CPU1 ---- ---- user accesses memory using RW PTE [PTE now cached in TLB] try_to_unmap_one() ==> ptep_get_and_clear() ==> set_tlb_ubc_flush_pending() mprotect(addr, PROT_READ) ==> change_pte_range() ==> [ PTE non-present - no flush ] user writes using cached RW PTE ... try_to_unmap_flush() The same type of race exists for reads when protecting for PROT_NONE and also exists for operations that can leave an old TLB entry behind such as munmap, mremap and madvise. For some operations like mprotect, it's not necessarily a data integrity issue but it is a correctness issue as there is a window where an mprotect that limits access still allows access. For munmap, it's potentially a data integrity issue although the race is massive as an munmap, mmap and return to userspace must all complete between the window when reclaim drops the PTL and flushes the TLB. However, it's theoritically possible so handle this issue by flushing the mm if reclaim is potentially currently batching TLB flushes. Other instances where a flush is required for a present pte should be ok as either the page lock is held preventing parallel reclaim or a page reference count is elevated preventing a parallel free leading to corruption. In the case of page_mkclean there isn't an obvious path that userspace could take advantage of without using the operations that are guarded by this patch. Other users such as gup as a race with reclaim looks just at PTEs. huge page variants should be ok as they don't race with reclaim. mincore only looks at PTEs. userfault also should be ok as if a parallel reclaim takes place, it will either fault the page back in or read some of the data before the flush occurs triggering a fault. Note that a variant of this patch was acked by Andy Lutomirski but this was for the x86 parts on top of his PCID work which didn't make the 4.13 merge window as expected. His ack is dropped from this version and there will be a follow-on patch on top of PCID that will include his ack. [akpm@linux-foundation.org: tweak comments] [akpm@linux-foundation.org: fix spello] Link: http://lkml.kernel.org/r/20170717155523.emckq2esjro6hf3z@suse.de Reported-by: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: <stable@vger.kernel.org> [v4.4+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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8bc3c3fe4f |
mm: drop NULL return check of pte_offset_map_lock()
pte_offset_map_lock() finds and takes ptl, and returns pte. But some callers return without unlocking the ptl when pte == NULL, which seems weird. Git history said that !pte check in change_pte_range() was introduced in commit |
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c2febafc67 |
mm: convert generic code to 5-level paging
Convert all non-architecture-specific code to 5-level paging. It's mostly mechanical adding handling one more page table level in places where we deal with pud_t. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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288bc54949 |
mm/autonuma: let architecture override how the write bit should be stashed in a protnone pte.
Patch series "Numabalancing preserve write fix", v2.
This patch series address an issue w.r.t THP migration and autonuma
preserve write feature. migrate_misplaced_transhuge_page() cannot deal
with concurrent modification of the page. It does a page copy without
following the migration pte sequence. IIUC, this was done to keep the
migration simpler and at the time of implemenation we didn't had THP
page cache which would have required a more elaborate migration scheme.
That means thp autonuma migration expect the protnone with saved write
to be done such that both kernel and user cannot update the page
content. This patch series enables archs like ppc64 to do that. We are
good with the hash translation mode with the current code, because we
never create a hardware page table entry for a protnone pte.
This patch (of 2):
Autonuma preserves the write permission across numa fault to avoid
taking a writefault after a numa fault (Commit:
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175ad4f1e7 |
mm: mprotect: use pmd_trans_unstable instead of taking the pmd_lock
pmd_trans_unstable does an atomic read on the pmd so it doesn't require the pmd_lock for the same check. This also removes the special assumption that the mmap_sem is hold for writing if prot_numa is not set. userfaultfd will hold the mmap_sem only for reading in change_pte_range like prot_numa, but it will not set prot_numa. This is always a valid micro-optimization regardless of userfaultfd. [kirill@shutemov.name: drop unneeded pmd_trans_unstable(pmd) check after __split_huge_pmd()] Link: http://lkml.kernel.org/r/20170208120421.GE5578@node.shutemov.name Link: http://lkml.kernel.org/r/20161216144821.5183-43-aarcange@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Michael Rapoport <RAPOPORT@il.ibm.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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7c0f6ba682 |
Replace <asm/uaccess.h> with <linux/uaccess.h> globally
This was entirely automated, using the script by Al: PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>' sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \ $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h) to do the replacement at the end of the merge window. Requested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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c7142aead8 |
mm/pkeys: generate pkey system call code only if ARCH_HAS_PKEYS is selected
Having code for the pkey_mprotect, pkey_alloc and pkey_free system calls makes only sense if ARCH_HAS_PKEYS is selected. If not selected these system calls will always return -ENOSPC or -EINVAL. To simplify things and have less code generate the pkey system call code only if ARCH_HAS_PKEYS is selected. For architectures which have already wired up the system calls, but do not select ARCH_HAS_PKEYS this will result in less generated code and a different return code: the three system calls will now always return -ENOSYS, using the cond_syscall mechanism. For architectures which have not wired up the system calls less unreachable code will be generated. Link: http://lkml.kernel.org/r/20161114111251.70084-1-heiko.carstens@de.ibm.com Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Acked-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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fd60775aea |
mm, thp: avoid unlikely branches for split_huge_pmd
While doing MADV_DONTNEED on a large area of thp memory, I noticed we encountered many unlikely() branches in profiles for each backing hugepage. This is because zap_pmd_range() would call split_huge_pmd(), which rechecked the conditions that were already validated, but as part of an unlikely() branch. Avoid the unlikely() branch when in a context where pmd is known to be good for __split_huge_pmd() directly. Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1610181600300.84525@chino.kir.corp.google.com Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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3e32158767 |
mm/mprotect.c: don't touch single threaded PTEs which are on the right node
We had some problems with pages getting unmapped in single threaded affinitized processes. It was tracked down to NUMA scanning. In this case it doesn't make any sense to unmap pages if the process is single threaded and the page is already on the node the process is running on. Add a check for this case into the numa protection code, and skip unmapping if true. In theory the process could be migrated later, but we will eventually rescan and unmap and migrate then. In theory this could be made more fancy: remembering this state per process or even whole mm. However that would need extra tracking and be more complicated, and the simple check seems to work fine so far. [ak@linux.intel.com: v3: Minor updates from Mel. Change code layout] Link: http://lkml.kernel.org/r/1476382117-5440-1-git-send-email-andi@firstfloor.org Link: http://lkml.kernel.org/r/1476288949-20970-1-git-send-email-andi@firstfloor.org Signed-off-by: Andi Kleen <ak@linux.intel.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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137baabe35 |
mm/numa: Remove duplicated include from mprotect.c
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: linux-mm@kvack.org Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Link: http://lkml.kernel.org/r/1476719259-6214-1-git-send-email-weiyj.lk@gmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> |
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93c26d7dc0 |
Merge branch 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull protection keys syscall interface from Thomas Gleixner: "This is the final step of Protection Keys support which adds the syscalls so user space can actually allocate keys and protect memory areas with them. Details and usage examples can be found in the documentation. The mm side of this has been acked by Mel" * 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/pkeys: Update documentation x86/mm/pkeys: Do not skip PKRU register if debug registers are not used x86/pkeys: Fix pkeys build breakage for some non-x86 arches x86/pkeys: Add self-tests x86/pkeys: Allow configuration of init_pkru x86/pkeys: Default to a restrictive init PKRU pkeys: Add details of system call use to Documentation/ generic syscalls: Wire up memory protection keys syscalls x86: Wire up protection keys system calls x86/pkeys: Allocation/free syscalls x86/pkeys: Make mprotect_key() mask off additional vm_flags mm: Implement new pkey_mprotect() system call x86/pkeys: Add fault handling for PF_PK page fault bit |
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e86f15ee64 |
mm: vma_merge: fix vm_page_prot SMP race condition against rmap_walk
The rmap_walk can access vm_page_prot (and potentially vm_flags in the pte/pmd manipulations). So it's not safe to wait the caller to update the vm_page_prot/vm_flags after vma_merge returned potentially removing the "next" vma and extending the "current" vma over the next->vm_start,vm_end range, but still with the "current" vma vm_page_prot, after releasing the rmap locks. The vm_page_prot/vm_flags must be transferred from the "next" vma to the current vma while vma_merge still holds the rmap locks. The side effect of this race condition is pte corruption during migrate as remove_migration_ptes when run on a address of the "next" vma that got removed, used the vm_page_prot of the current vma. migrate mprotect ------------ ------------- migrating in "next" vma vma_merge() # removes "next" vma and # extends "current" vma # current vma is not with # vm_page_prot updated remove_migration_ptes read vm_page_prot of current "vma" establish pte with wrong permissions vm_set_page_prot(vma) # too late! change_protection in the old vma range only, next range is not updated This caused segmentation faults and potentially memory corruption in heavy mprotect loads with some light page migration caused by compaction in the background. Hugh Dickins pointed out the comment about the Odd case 8 in vma_merge which confirms the case 8 is only buggy one where the race can trigger, in all other vma_merge cases the above cannot happen. This fix removes the oddness factor from case 8 and it converts it from: AAAA PPPPNNNNXXXX -> PPPPNNNNNNNN to: AAAA PPPPNNNNXXXX -> PPPPXXXXXXXX XXXX has the right vma properties for the whole merged vma returned by vma_adjust, so it solves the problem fully. It has the added benefits that the callers could stop updating vma properties when vma_merge succeeds however the callers are not updated by this patch (there are bits like VM_SOFTDIRTY that still need special care for the whole range, as the vma merging ignores them, but as long as they're not processed by rmap walks and instead they're accessed with the mmap_sem at least for reading, they are fine not to be updated within vma_adjust before releasing the rmap_locks). Link: http://lkml.kernel.org/r/1474309513-20313-1-git-send-email-aarcange@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reported-by: Aditya Mandaleeka <adityam@microsoft.com> Cc: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Jan Vorlicek <janvorli@microsoft.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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6d2329f887 |
mm: vm_page_prot: update with WRITE_ONCE/READ_ONCE
vma->vm_page_prot is read lockless from the rmap_walk, it may be updated concurrently and this prevents the risk of reading intermediate values. Link: http://lkml.kernel.org/r/1474660305-19222-1-git-send-email-aarcange@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Jan Vorlicek <janvorli@microsoft.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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e8c24d3a23 |
x86/pkeys: Allocation/free syscalls
This patch adds two new system calls: int pkey_alloc(unsigned long flags, unsigned long init_access_rights) int pkey_free(int pkey); These implement an "allocator" for the protection keys themselves, which can be thought of as analogous to the allocator that the kernel has for file descriptors. The kernel tracks which numbers are in use, and only allows operations on keys that are valid. A key which was not obtained by pkey_alloc() may not, for instance, be passed to pkey_mprotect(). These system calls are also very important given the kernel's use of pkeys to implement execute-only support. These help ensure that userspace can never assume that it has control of a key unless it first asks the kernel. The kernel does not promise to preserve PKRU (right register) contents except for allocated pkeys. The 'init_access_rights' argument to pkey_alloc() specifies the rights that will be established for the returned pkey. For instance: pkey = pkey_alloc(flags, PKEY_DENY_WRITE); will allocate 'pkey', but also sets the bits in PKRU[1] such that writing to 'pkey' is already denied. The kernel does not prevent pkey_free() from successfully freeing in-use pkeys (those still assigned to a memory range by pkey_mprotect()). It would be expensive to implement the checks for this, so we instead say, "Just don't do it" since sane software will never do it anyway. Any piece of userspace calling pkey_alloc() needs to be prepared for it to fail. Why? pkey_alloc() returns the same error code (ENOSPC) when there are no pkeys and when pkeys are unsupported. They can be unsupported for a whole host of reasons, so apps must be prepared for this. Also, libraries or LD_PRELOADs might steal keys before an application gets access to them. This allocation mechanism could be implemented in userspace. Even if we did it in userspace, we would still need additional user/kernel interfaces to tell userspace which keys are being used by the kernel internally (such as for execute-only mappings). Having the kernel provide this facility completely removes the need for these additional interfaces, or having an implementation of this in userspace at all. Note that we have to make changes to all of the architectures that do not use mman-common.h because we use the new PKEY_DENY_ACCESS/WRITE macros in arch-independent code. 1. PKRU is the Protection Key Rights User register. It is a usermode-accessible register that controls whether writes and/or access to each individual pkey is allowed or denied. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: linux-arch@vger.kernel.org Cc: Dave Hansen <dave@sr71.net> Cc: arnd@arndb.de Cc: linux-api@vger.kernel.org Cc: linux-mm@kvack.org Cc: luto@kernel.org Cc: akpm@linux-foundation.org Cc: torvalds@linux-foundation.org Link: http://lkml.kernel.org/r/20160729163015.444FE75F@viggo.jf.intel.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> |
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a8502b67d7 |
x86/pkeys: Make mprotect_key() mask off additional vm_flags
Today, mprotect() takes 4 bits of data: PROT_READ/WRITE/EXEC/NONE. Three of those bits: READ/WRITE/EXEC get translated directly in to vma->vm_flags by calc_vm_prot_bits(). If a bit is unset in mprotect()'s 'prot' argument then it must be cleared in vma->vm_flags during the mprotect() call. We do this clearing today by first calculating the VMA flags we want set, then clearing the ones we do not want to inherit from the original VMA: vm_flags = calc_vm_prot_bits(prot, key); ... newflags = vm_flags; newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC)); However, we *also* want to mask off the original VMA's vm_flags in which we store the protection key. To do that, this patch adds a new macro: ARCH_VM_PKEY_FLAGS which allows the architecture to specify additional bits that it would like cleared. We use that to ensure that the VM_PKEY_BIT* bits get cleared. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arch@vger.kernel.org Cc: Dave Hansen <dave@sr71.net> Cc: arnd@arndb.de Cc: linux-api@vger.kernel.org Cc: linux-mm@kvack.org Cc: luto@kernel.org Cc: akpm@linux-foundation.org Cc: torvalds@linux-foundation.org Link: http://lkml.kernel.org/r/20160729163013.E48D6981@viggo.jf.intel.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> |
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7d06d9c9bd |
mm: Implement new pkey_mprotect() system call
pkey_mprotect() is just like mprotect, except it also takes a protection key as an argument. On systems that do not support protection keys, it still works, but requires that key=0. Otherwise it does exactly what mprotect does. I expect it to get used like this, if you want to guarantee that any mapping you create can *never* be accessed without the right protection keys set up. int real_prot = PROT_READ|PROT_WRITE; pkey = pkey_alloc(0, PKEY_DENY_ACCESS); ptr = mmap(NULL, PAGE_SIZE, PROT_NONE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0); ret = pkey_mprotect(ptr, PAGE_SIZE, real_prot, pkey); This way, there is *no* window where the mapping is accessible since it was always either PROT_NONE or had a protection key set that denied all access. We settled on 'unsigned long' for the type of the key here. We only need 4 bits on x86 today, but I figured that other architectures might need some more space. Semantically, we have a bit of a problem if we combine this syscall with our previously-introduced execute-only support: What do we do when we mix execute-only pkey use with pkey_mprotect() use? For instance: pkey_mprotect(ptr, PAGE_SIZE, PROT_WRITE, 6); // set pkey=6 mprotect(ptr, PAGE_SIZE, PROT_EXEC); // set pkey=X_ONLY_PKEY? mprotect(ptr, PAGE_SIZE, PROT_WRITE); // is pkey=6 again? To solve that, we make the plain-mprotect()-initiated execute-only support only apply to VMAs that have the default protection key (0) set on them. Proposed semantics: 1. protection key 0 is special and represents the default, "unassigned" protection key. It is always allocated. 2. mprotect() never affects a mapping's pkey_mprotect()-assigned protection key. A protection key of 0 (even if set explicitly) represents an unassigned protection key. 2a. mprotect(PROT_EXEC) on a mapping with an assigned protection key may or may not result in a mapping with execute-only properties. pkey_mprotect() plus pkey_set() on all threads should be used to _guarantee_ execute-only semantics if this is not a strong enough semantic. 3. mprotect(PROT_EXEC) may result in an "execute-only" mapping. The kernel will internally attempt to allocate and dedicate a protection key for the purpose of execute-only mappings. This may not be possible in cases where there are no free protection keys available. It can also happen, of course, in situations where there is no hardware support for protection keys. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: linux-arch@vger.kernel.org Cc: Dave Hansen <dave@sr71.net> Cc: arnd@arndb.de Cc: linux-api@vger.kernel.org Cc: linux-mm@kvack.org Cc: luto@kernel.org Cc: akpm@linux-foundation.org Cc: torvalds@linux-foundation.org Link: http://lkml.kernel.org/r/20160729163012.3DDD36C4@viggo.jf.intel.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> |
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337d9abf1c |
mm: thp: check pmd_trans_unstable() after split_huge_pmd()
split_huge_pmd() doesn't guarantee that the pmd is normal pmd pointing to pte entries, which can be checked with pmd_trans_unstable(). Some callers make this assertion and some do it differently and some not, so let's do it in a unified manner. Link: http://lkml.kernel.org/r/1464741400-12143-1-git-send-email-n-horiguchi@ah.jp.nec.com Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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dc0ef0df7b |
mm: make mmap_sem for write waits killable for mm syscalls
This is a follow up work for oom_reaper [1]. As the async OOM killing depends on oom_sem for read we would really appreciate if a holder for write didn't stood in the way. This patchset is changing many of down_write calls to be killable to help those cases when the writer is blocked and waiting for readers to release the lock and so help __oom_reap_task to process the oom victim. Most of the patches are really trivial because the lock is help from a shallow syscall paths where we can return EINTR trivially and allow the current task to die (note that EINTR will never get to the userspace as the task has fatal signal pending). Others seem to be easy as well as the callers are already handling fatal errors and bail and return to userspace which should be sufficient to handle the failure gracefully. I am not familiar with all those code paths so a deeper review is really appreciated. As this work is touching more areas which are not directly connected I have tried to keep the CC list as small as possible and people who I believed would be familiar are CCed only to the specific patches (all should have received the cover though). This patchset is based on linux-next and it depends on down_write_killable for rw_semaphores which got merged into tip locking/rwsem branch and it is merged into this next tree. I guess it would be easiest to route these patches via mmotm because of the dependency on the tip tree but if respective maintainers prefer other way I have no objections. I haven't covered all the mmap_write(mm->mmap_sem) instances here $ git grep "down_write(.*\<mmap_sem\>)" next/master | wc -l 98 $ git grep "down_write(.*\<mmap_sem\>)" | wc -l 62 I have tried to cover those which should be relatively easy to review in this series because this alone should be a nice improvement. Other places can be changed on top. [0] http://lkml.kernel.org/r/1456752417-9626-1-git-send-email-mhocko@kernel.org [1] http://lkml.kernel.org/r/1452094975-551-1-git-send-email-mhocko@kernel.org [2] http://lkml.kernel.org/r/1456750705-7141-1-git-send-email-mhocko@kernel.org This patch (of 18): This is the first step in making mmap_sem write waiters killable. It focuses on the trivial ones which are taking the lock early after entering the syscall and they are not changing state before. Therefore it is very easy to change them to use down_write_killable and immediately return with -EINTR. This will allow the waiter to pass away without blocking the mmap_sem which might be required to make a forward progress. E.g. the oom reaper will need the lock for reading to dismantle the OOM victim address space. The only tricky function in this patch is vm_mmap_pgoff which has many call sites via vm_mmap. To reduce the risk keep vm_mmap with the original non-killable semantic for now. vm_munmap callers do not bother checking the return value so open code it into the munmap syscall path for now for simplicity. Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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f138556daf |
mm/mprotect.c: don't imply PROT_EXEC on non-exec fs
The mprotect(PROT_READ) fails when called by the READ_IMPLIES_EXEC binary on a memory mapped file located on non-exec fs. The mprotect does not check whether fs is _executable_ or not. The PROT_EXEC flag is set automatically even if a memory mapped file is located on non-exec fs. Fix it by checking whether a memory mapped file is located on a non-exec fs. If so the PROT_EXEC is not implied by the PROT_READ. The implementation uses the VM_MAYEXEC flag set properly in mmap. Now it is consistent with mmap. I did the isolated tests (PT_GNU_STACK X/NX, multiple VMAs, X/NX fs). I also patched the official 3.19.0-47-generic Ubuntu 14.04 kernel and it seems to work. Signed-off-by: Piotr Kwapulinski <kwapulinski.piotr@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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62b5f7d013 |
mm/core, x86/mm/pkeys: Add execute-only protection keys support
Protection keys provide new page-based protection in hardware. But, they have an interesting attribute: they only affect data accesses and never affect instruction fetches. That means that if we set up some memory which is set as "access-disabled" via protection keys, we can still execute from it. This patch uses protection keys to set up mappings to do just that. If a user calls: mmap(..., PROT_EXEC); or mprotect(ptr, sz, PROT_EXEC); (note PROT_EXEC-only without PROT_READ/WRITE), the kernel will notice this, and set a special protection key on the memory. It also sets the appropriate bits in the Protection Keys User Rights (PKRU) register so that the memory becomes unreadable and unwritable. I haven't found any userspace that does this today. With this facility in place, we expect userspace to move to use it eventually. Userspace _could_ start doing this today. Any PROT_EXEC calls get converted to PROT_READ inside the kernel, and would transparently be upgraded to "true" PROT_EXEC with this code. IOW, userspace never has to do any PROT_EXEC runtime detection. This feature provides enhanced protection against leaking executable memory contents. This helps thwart attacks which are attempting to find ROP gadgets on the fly. But, the security provided by this approach is not comprehensive. The PKRU register which controls access permissions is a normal user register writable from unprivileged userspace. An attacker who can execute the 'wrpkru' instruction can easily disable the protection provided by this feature. The protection key that is used for execute-only support is permanently dedicated at compile time. This is fine for now because there is currently no API to set a protection key other than this one. Despite there being a constant PKRU value across the entire system, we do not set it unless this feature is in use in a process. That is to preserve the PKRU XSAVE 'init state', which can lead to faster context switches. PKRU *is* a user register and the kernel is modifying it. That means that code doing: pkru = rdpkru() pkru |= 0x100; mmap(..., PROT_EXEC); wrpkru(pkru); could lose the bits in PKRU that enforce execute-only permissions. To avoid this, we suggest avoiding ever calling mmap() or mprotect() when the PKRU value is expected to be unstable. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bp@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Chen Gang <gang.chen.5i5j@gmail.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dave Hansen <dave@sr71.net> Cc: David Hildenbrand <dahi@linux.vnet.ibm.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kees Cook <keescook@chromium.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Piotr Kwapulinski <kwapulinski.piotr@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: Vladimir Murzin <vladimir.murzin@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: keescook@google.com Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20160212210240.CB4BB5CA@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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e6bfb70959 |
mm/core, arch, powerpc: Pass a protection key in to calc_vm_flag_bits()
This plumbs a protection key through calc_vm_flag_bits(). We could have done this in calc_vm_prot_bits(), but I did not feel super strongly which way to go. It was pretty arbitrary which one to use. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Arve Hjønnevåg <arve@android.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Chen Gang <gang.chen.5i5j@gmail.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dave Hansen <dave@sr71.net> Cc: David Airlie <airlied@linux.ie> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Geliang Tang <geliangtang@163.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Leon Romanovsky <leon@leon.nu> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Riley Andrews <riandrews@android.com> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: devel@driverdev.osuosl.org Cc: linux-api@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org Cc: linuxppc-dev@lists.ozlabs.org Link: http://lkml.kernel.org/r/20160212210231.E6F1F0D6@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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6b9116a652 |
mm, dax: check for pmd_none() after split_huge_pmd()
DAX implements split_huge_pmd() by clearing pmd. This simple approach reduces memory overhead, as we don't need to deposit page table on huge page mapping to make split_huge_pmd() never-fail. PTE table can be allocated and populated later on page fault from backing store. But one side effect is that have to check if pmd is pmd_none() after split_huge_pmd(). In most places we do this already to deal with parallel MADV_DONTNEED. But I found two call sites which is not affected by MADV_DONTNEED (due down_write(mmap_sem)), but need to have the check to work with DAX properly. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Matthew Wilcox <willy@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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5c7fb56e5e |
mm, dax: dax-pmd vs thp-pmd vs hugetlbfs-pmd
A dax-huge-page mapping while it uses some thp helpers is ultimately not a transparent huge page. The distinction is especially important in the get_user_pages() path. pmd_devmap() is used to distinguish dax-pmds from pmd_huge() and pmd_trans_huge() which have slightly different semantics. Explicitly mark the pmd_trans_huge() helpers that dax needs by adding pmd_devmap() checks. [kirill.shutemov@linux.intel.com: fix regression in handling mlocked pages in __split_huge_pmd()] Signed-off-by: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave@sr71.net> Cc: Mel Gorman <mgorman@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Matthew Wilcox <willy@linux.intel.com> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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78ddc53473 |
thp: rename split_huge_page_pmd() to split_huge_pmd()
We are going to decouple splitting THP PMD from splitting underlying compound page. This patch renames split_huge_page_pmd*() functions to split_huge_pmd*() to reflect the fact that it doesn't imply page splitting, only PMD. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Tested-by: Sasha Levin <sasha.levin@oracle.com> Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Jerome Marchand <jmarchan@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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8463833590 |
mm: rework virtual memory accounting
When inspecting a vague code inside prctl(PR_SET_MM_MEM) call (which testing the RLIMIT_DATA value to figure out if we're allowed to assign new @start_brk, @brk, @start_data, @end_data from mm_struct) it's been commited that RLIMIT_DATA in a form it's implemented now doesn't do anything useful because most of user-space libraries use mmap() syscall for dynamic memory allocations. Linus suggested to convert RLIMIT_DATA rlimit into something suitable for anonymous memory accounting. But in this patch we go further, and the changes are bundled together as: * keep vma counting if CONFIG_PROC_FS=n, will be used for limits * replace mm->shared_vm with better defined mm->data_vm * account anonymous executable areas as executable * account file-backed growsdown/up areas as stack * drop struct file* argument from vm_stat_account * enforce RLIMIT_DATA for size of data areas This way code looks cleaner: now code/stack/data classification depends only on vm_flags state: VM_EXEC & ~VM_WRITE -> code (VmExe + VmLib in proc) VM_GROWSUP | VM_GROWSDOWN -> stack (VmStk) VM_WRITE & ~VM_SHARED & !stack -> data (VmData) The rest (VmSize - VmData - VmStk - VmExe - VmLib) could be called "shared", but that might be strange beast like readonly-private or VM_IO area. - RLIMIT_AS limits whole address space "VmSize" - RLIMIT_STACK limits stack "VmStk" (but each vma individually) - RLIMIT_DATA now limits "VmData" Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Cc: Vegard Nossum <vegard.nossum@oracle.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Willy Tarreau <w@1wt.eu> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Kees Cook <keescook@google.com> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Pavel Emelyanov <xemul@virtuozzo.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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19a809afe2 |
userfaultfd: teach vma_merge to merge across vma->vm_userfaultfd_ctx
vma->vm_userfaultfd_ctx is yet another vma parameter that vma_merge must be aware about so that we can merge vmas back like they were originally before arming the userfaultfd on some memory range. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Pavel Emelyanov <xemul@parallels.com> Cc: Sanidhya Kashyap <sanidhya.gatech@gmail.com> Cc: zhang.zhanghailiang@huawei.com Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Andres Lagar-Cavilla <andreslc@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Hugh Dickins <hughd@google.com> Cc: Peter Feiner <pfeiner@google.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Huangpeng (Peter)" <peter.huangpeng@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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36f881883c |
mm: fix mprotect() behaviour on VM_LOCKED VMAs
On mlock(2) we trigger COW on private writable VMA to avoid faults in future. mm/gup.c: 840 long populate_vma_page_range(struct vm_area_struct *vma, 841 unsigned long start, unsigned long end, int *nonblocking) 842 { ... 855 * We want to touch writable mappings with a write fault in order 856 * to break COW, except for shared mappings because these don't COW 857 * and we would not want to dirty them for nothing. 858 */ 859 if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE) 860 gup_flags |= FOLL_WRITE; But we miss this case when we make VM_LOCKED VMA writeable via mprotect(2). The test case: #define _GNU_SOURCE #include <fcntl.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/mman.h> #include <sys/resource.h> #include <sys/stat.h> #include <sys/time.h> #include <sys/types.h> #define PAGE_SIZE 4096 int main(int argc, char **argv) { struct rusage usage; long before; char *p; int fd; /* Create a file and populate first page of page cache */ fd = open("/tmp", O_TMPFILE | O_RDWR, S_IRUSR | S_IWUSR); write(fd, "1", 1); /* Create a *read-only* *private* mapping of the file */ p = mmap(NULL, PAGE_SIZE, PROT_READ, MAP_PRIVATE, fd, 0); /* * Since the mapping is read-only, mlock() will populate the mapping * with PTEs pointing to page cache without triggering COW. */ mlock(p, PAGE_SIZE); /* * Mapping became read-write, but it's still populated with PTEs * pointing to page cache. */ mprotect(p, PAGE_SIZE, PROT_READ | PROT_WRITE); getrusage(RUSAGE_SELF, &usage); before = usage.ru_minflt; /* Trigger COW: fault in mlock()ed VMA. */ *p = 1; getrusage(RUSAGE_SELF, &usage); printf("faults: %ld\n", usage.ru_minflt - before); return 0; } $ ./test faults: 1 Let's fix it by triggering populating of VMA in mprotect_fixup() on this condition. We don't care about population error as we don't in other similar cases i.e. mremap. [akpm@linux-foundation.org: tweak comment text] Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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b191f9b106 |
mm: numa: preserve PTE write permissions across a NUMA hinting fault
Protecting a PTE to trap a NUMA hinting fault clears the writable bit and further faults are needed after trapping a NUMA hinting fault to set the writable bit again. This patch preserves the writable bit when trapping NUMA hinting faults. The impact is obvious from the number of minor faults trapped during the basis balancing benchmark and the system CPU usage; autonumabench 4.0.0-rc4 4.0.0-rc4 baseline preserve Time System-NUMA01 107.13 ( 0.00%) 103.13 ( 3.73%) Time System-NUMA01_THEADLOCAL 131.87 ( 0.00%) 83.30 ( 36.83%) Time System-NUMA02 8.95 ( 0.00%) 10.72 (-19.78%) Time System-NUMA02_SMT 4.57 ( 0.00%) 3.99 ( 12.69%) Time Elapsed-NUMA01 515.78 ( 0.00%) 517.26 ( -0.29%) Time Elapsed-NUMA01_THEADLOCAL 384.10 ( 0.00%) 384.31 ( -0.05%) Time Elapsed-NUMA02 48.86 ( 0.00%) 48.78 ( 0.16%) Time Elapsed-NUMA02_SMT 47.98 ( 0.00%) 48.12 ( -0.29%) 4.0.0-rc4 4.0.0-rc4 baseline preserve User 44383.95 43971.89 System 252.61 201.24 Elapsed 998.68 1000.94 Minor Faults 2597249 1981230 Major Faults 365 364 There is a similar drop in system CPU usage using Dave Chinner's xfsrepair workload 4.0.0-rc4 4.0.0-rc4 baseline preserve Amean real-xfsrepair 454.14 ( 0.00%) 442.36 ( 2.60%) Amean syst-xfsrepair 277.20 ( 0.00%) 204.68 ( 26.16%) The patch looks hacky but the alternatives looked worse. The tidest was to rewalk the page tables after a hinting fault but it was more complex than this approach and the performance was worse. It's not generally safe to just mark the page writable during the fault if it's a write fault as it may have been read-only for COW so that approach was discarded. Signed-off-by: Mel Gorman <mgorman@suse.de> Reported-by: Dave Chinner <david@fromorbit.com> Tested-by: Dave Chinner <david@fromorbit.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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10c1045f28 |
mm: numa: avoid unnecessary TLB flushes when setting NUMA hinting entries
If a PTE or PMD is already marked NUMA when scanning to mark entries for NUMA hinting then it is not necessary to update the entry and incur a TLB flush penalty. Avoid the avoidhead where possible. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Jones <davej@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Rik van Riel <riel@redhat.com> Cc: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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e944fd67b6 |
mm: numa: do not trap faults on the huge zero page
Faults on the huge zero page are pointless and there is a BUG_ON to catch them during fault time. This patch reintroduces a check that avoids marking the zero page PAGE_NONE. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Jones <davej@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Rik van Riel <riel@redhat.com> Cc: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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4d94246699 |
mm: convert p[te|md]_mknonnuma and remaining page table manipulations
With PROT_NONE, the traditional page table manipulation functions are sufficient. [andre.przywara@arm.com: fix compiler warning in pmdp_invalidate()] [akpm@linux-foundation.org: fix build with STRICT_MM_TYPECHECKS] Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Tested-by: Sasha Levin <sasha.levin@oracle.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Jones <davej@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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8a0516ed8b |
mm: convert p[te|md]_numa users to p[te|md]_protnone_numa
Convert existing users of pte_numa and friends to the new helper. Note that the kernel is broken after this patch is applied until the other page table modifiers are also altered. This patch layout is to make review easier. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Tested-by: Sasha Levin <sasha.levin@oracle.com> Cc: Dave Jones <davej@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Rik van Riel <riel@redhat.com> Cc: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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0661a33611 |
mm: remove rest usage of VM_NONLINEAR and pte_file()
One bit in ->vm_flags is unused now! Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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64e455079e |
mm: softdirty: enable write notifications on VMAs after VM_SOFTDIRTY cleared
For VMAs that don't want write notifications, PTEs created for read faults
have their write bit set. If the read fault happens after VM_SOFTDIRTY is
cleared, then the PTE's softdirty bit will remain clear after subsequent
writes.
Here's a simple code snippet to demonstrate the bug:
char* m = mmap(NULL, getpagesize(), PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_SHARED, -1, 0);
system("echo 4 > /proc/$PPID/clear_refs"); /* clear VM_SOFTDIRTY */
assert(*m == '\0'); /* new PTE allows write access */
assert(!soft_dirty(x));
*m = 'x'; /* should dirty the page */
assert(soft_dirty(x)); /* fails */
With this patch, write notifications are enabled when VM_SOFTDIRTY is
cleared. Furthermore, to avoid unnecessary faults, write notifications
are disabled when VM_SOFTDIRTY is set.
As a side effect of enabling and disabling write notifications with
care, this patch fixes a bug in mprotect where vm_page_prot bits set by
drivers were zapped on mprotect. An analogous bug was fixed in mmap by
commit
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a5338093bf |
mm: move mmu notifier call from change_protection to change_pmd_range
The NUMA scanning code can end up iterating over many gigabytes of unpopulated memory, especially in the case of a freshly started KVM guest with lots of memory. This results in the mmu notifier code being called even when there are no mapped pages in a virtual address range. The amount of time wasted can be enough to trigger soft lockup warnings with very large KVM guests. This patch moves the mmu notifier call to the pmd level, which represents 1GB areas of memory on x86-64. Furthermore, the mmu notifier code is only called from the address in the PMD where present mappings are first encountered. The hugetlbfs code is left alone for now; hugetlb mappings are not relocatable, and as such are left alone by the NUMA code, and should never trigger this problem to begin with. Signed-off-by: Rik van Riel <riel@redhat.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Reported-by: Xing Gang <gang.xing@hp.com> Tested-by: Chegu Vinod <chegu_vinod@hp.com> Cc: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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1ad9f620c3 |
mm: numa: recheck for transhuge pages under lock during protection changes
Sasha reported the following bug using trinity kernel BUG at mm/mprotect.c:149! invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 20 PID: 26219 Comm: trinity-c216 Tainted: G W 3.14.0-rc5-next-20140305-sasha-00011-ge06f5f3-dirty #105 task: ffff8800b6c80000 ti: ffff880228436000 task.ti: ffff880228436000 RIP: change_protection_range+0x3b3/0x500 Call Trace: change_protection+0x25/0x30 change_prot_numa+0x1b/0x30 task_numa_work+0x279/0x360 task_work_run+0xae/0xf0 do_notify_resume+0x8e/0xe0 retint_signal+0x4d/0x92 The VM_BUG_ON was added in -mm by the patch "mm,numa: reorganize change_pmd_range". The race existed without the patch but was just harder to hit. The problem is that a transhuge check is made without holding the PTL. It's possible at the time of the check that a parallel fault clears the pmd and inserts a new one which then triggers the VM_BUG_ON check. This patch removes the VM_BUG_ON but fixes the race by rechecking transhuge under the PTL when marking page tables for NUMA hinting and bailing if a race occurred. It is not a problem for calls to mprotect() as they hold mmap_sem for write. Signed-off-by: Mel Gorman <mgorman@suse.de> Reported-by: Sasha Levin <sasha.levin@oracle.com> Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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88a9ab6e3d |
mm,numa: reorganize change_pmd_range()
Reorganize the order of ifs in change_pmd_range a little, in preparation for the next patch. [akpm@linux-foundation.org: fix indenting, per David] Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Reported-by: Xing Gang <gang.xing@hp.com> Tested-by: Chegu Vinod <chegu_vinod@hp.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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56eecdb912 |
mm: Use ptep/pmdp_set_numa() for updating _PAGE_NUMA bit
Archs like ppc64 doesn't do tlb flush in set_pte/pmd functions when using a hash table MMU for various reasons (the flush is handled as part of the PTE modification when necessary). ppc64 thus doesn't implement flush_tlb_range for hash based MMUs. Additionally ppc64 require the tlb flushing to be batched within ptl locks. The reason to do that is to ensure that the hash page table is in sync with linux page table. We track the hpte index in linux pte and if we clear them without flushing hash and drop the ptl lock, we can have another cpu update the pte and can end up with duplicate entry in the hash table, which is fatal. We also want to keep set_pte_at simpler by not requiring them to do hash flush for performance reason. We do that by assuming that set_pte_at() is never *ever* called on a PTE that is already valid. This was the case until the NUMA code went in which broke that assumption. Fix that by introducing a new pair of helpers to set _PAGE_NUMA in a way similar to ptep/pmdp_set_wrprotect(), with a generic implementation using set_pte_at() and a powerpc specific one using the appropriate mechanism needed to keep the hash table in sync. Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> |
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9d85d5863f |
mm: Dirty accountable change only apply to non prot numa case
So move it within the if loop Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> |
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64a9a34e22 |
mm: numa: do not automatically migrate KSM pages
KSM pages can be shared between tasks that are not necessarily related to each other from a NUMA perspective. This patch causes those pages to be ignored by automatic NUMA balancing so they do not migrate and do not cause unrelated tasks to be grouped together. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Alex Thorlton <athorlton@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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2084140594 |
mm: fix TLB flush race between migration, and change_protection_range
There are a few subtle races, between change_protection_range (used by mprotect and change_prot_numa) on one side, and NUMA page migration and compaction on the other side. The basic race is that there is a time window between when the PTE gets made non-present (PROT_NONE or NUMA), and the TLB is flushed. During that time, a CPU may continue writing to the page. This is fine most of the time, however compaction or the NUMA migration code may come in, and migrate the page away. When that happens, the CPU may continue writing, through the cached translation, to what is no longer the current memory location of the process. This only affects x86, which has a somewhat optimistic pte_accessible. All other architectures appear to be safe, and will either always flush, or flush whenever there is a valid mapping, even with no permissions (SPARC). The basic race looks like this: CPU A CPU B CPU C load TLB entry make entry PTE/PMD_NUMA fault on entry read/write old page start migrating page change PTE/PMD to new page read/write old page [*] flush TLB reload TLB from new entry read/write new page lose data [*] the old page may belong to a new user at this point! The obvious fix is to flush remote TLB entries, by making sure that pte_accessible aware of the fact that PROT_NONE and PROT_NUMA memory may still be accessible if there is a TLB flush pending for the mm. This should fix both NUMA migration and compaction. [mgorman@suse.de: fix build] Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Alex Thorlton <athorlton@sgi.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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1667918b64 |
mm: numa: clear numa hinting information on mprotect
On a protection change it is no longer clear if the page should be still accessible. This patch clears the NUMA hinting fault bits on a protection change. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Alex Thorlton <athorlton@sgi.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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0c5f83c23c |
mm: numa: do not clear PTE for pte_numa update
The TLB must be flushed if the PTE is updated but change_pte_range is clearing the PTE while marking PTEs pte_numa without necessarily flushing the TLB if it reinserts the same entry. Without the flush, it's conceivable that two processors have different TLBs for the same virtual address and at the very least it would generate spurious faults. This patch only unmaps the pages in change_pte_range for a full protection change. [riel@redhat.com: write pte_numa pte back to the page tables] Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Rik van Riel <riel@redhat.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Alex Thorlton <athorlton@sgi.com> Cc: Chegu Vinod <chegu_vinod@hp.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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72403b4a0f |
mm: numa: return the number of base pages altered by protection changes
Commit
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fb10d5b7ef |
Merge branch 'linus' into sched/core
Resolve cherry-picking conflicts:
Conflicts:
mm/huge_memory.c
mm/memory.c
mm/mprotect.c
See this upstream merge commit for more details:
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0255d49184 |
mm: Account for a THP NUMA hinting update as one PTE update
A THP PMD update is accounted for as 512 pages updated in vmstat. This is large difference when estimating the cost of automatic NUMA balancing and can be misleading when comparing results that had collapsed versus split THP. This patch addresses the accounting issue. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: <stable@kernel.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-10-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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c3d16e1652 |
mm: migration: do not lose soft dirty bit if page is in migration state
If page migration is turned on in config and the page is migrating, we may lose the soft dirty bit. If fork and mprotect are called on migrating pages (once migration is complete) pages do not obtain the soft dirty bit in the correspond pte entries. Fix it adding an appropriate test on swap entries. Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Matt Mackall <mpm@selenic.com> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Peter Zijlstra <peterz@infradead.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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0f19c17929 |
mm: numa: Do not batch handle PMD pages
With the THP migration races closed it is still possible to occasionally see corruption. The problem is related to handling PMD pages in batch. When a page fault is handled it can be assumed that the page being faulted will also be flushed from the TLB. The same flushing does not happen when handling PMD pages in batch. Fixing is straight forward but there are a number of reasons not to 1. Multiple TLB flushes may have to be sent depending on what pages get migrated 2. The handling of PMDs in batch means that faults get accounted to the task that is handling the fault. While care is taken to only mark PMDs where the last CPU and PID match it can still have problems due to PID truncation when matching PIDs. 3. Batching on the PMD level may reduce faults but setting pmd_numa requires taking a heavy lock that can contend with THP migration and handling the fault requires the release/acquisition of the PTL for every page migrated. It's still pretty heavy. PMD batch handling is not something that people ever have been happy with. This patch removes it and later patches will deal with the additional fault overhead using more installigent migrate rate adaption. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-48-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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90572890d2 |
mm: numa: Change page last {nid,pid} into {cpu,pid}
Change the per page last fault tracking to use cpu,pid instead of nid,pid. This will allow us to try and lookup the alternate task more easily. Note that even though it is the cpu that is store in the page flags that the mpol_misplaced decision is still based on the node. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/1381141781-10992-43-git-send-email-mgorman@suse.de [ Fixed build failure on 32-bit systems. ] Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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25cbbef192 |
mm: numa: Trap pmd hinting faults only if we would otherwise trap PTE faults
Base page PMD faulting is meant to batch handle NUMA hinting faults from PTEs. However, even is no PTE faults would ever be handled within a range the kernel still traps PMD hinting faults. This patch avoids the overhead. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-37-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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b795854b1f |
sched/numa: Set preferred NUMA node based on number of private faults
Ideally it would be possible to distinguish between NUMA hinting faults that are private to a task and those that are shared. If treated identically there is a risk that shared pages bounce between nodes depending on the order they are referenced by tasks. Ultimately what is desirable is that task private pages remain local to the task while shared pages are interleaved between sharing tasks running on different nodes to give good average performance. This is further complicated by THP as even applications that partition their data may not be partitioning on a huge page boundary. To start with, this patch assumes that multi-threaded or multi-process applications partition their data and that in general the private accesses are more important for cpu->memory locality in the general case. Also, no new infrastructure is required to treat private pages properly but interleaving for shared pages requires additional infrastructure. To detect private accesses the pid of the last accessing task is required but the storage requirements are a high. This patch borrows heavily from Ingo Molnar's patch "numa, mm, sched: Implement last-CPU+PID hash tracking" to encode some bits from the last accessing task in the page flags as well as the node information. Collisions will occur but it is better than just depending on the node information. Node information is then used to determine if a page needs to migrate. The PID information is used to detect private/shared accesses. The preferred NUMA node is selected based on where the maximum number of approximately private faults were measured. Shared faults are not taken into consideration for a few reasons. First, if there are many tasks sharing the page then they'll all move towards the same node. The node will be compute overloaded and then scheduled away later only to bounce back again. Alternatively the shared tasks would just bounce around nodes because the fault information is effectively noise. Either way accounting for shared faults the same as private faults can result in lower performance overall. The second reason is based on a hypothetical workload that has a small number of very important, heavily accessed private pages but a large shared array. The shared array would dominate the number of faults and be selected as a preferred node even though it's the wrong decision. The third reason is that multiple threads in a process will race each other to fault the shared page making the fault information unreliable. Signed-off-by: Mel Gorman <mgorman@suse.de> [ Fix complication error when !NUMA_BALANCING. ] Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-30-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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1bc115d87d |
mm: numa: Scan pages with elevated page_mapcount
Currently automatic NUMA balancing is unable to distinguish between false shared versus private pages except by ignoring pages with an elevated page_mapcount entirely. This avoids shared pages bouncing between the nodes whose task is using them but that is ignored quite a lot of data. This patch kicks away the training wheels in preparation for adding support for identifying shared/private pages is now in place. The ordering is so that the impact of the shared/private detection can be easily measured. Note that the patch does not migrate shared, file-backed within vmas marked VM_EXEC as these are generally shared library pages. Migrating such pages is not beneficial as there is an expectation they are read-shared between caches and iTLB and iCache pressure is generally low. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-28-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org> |