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userfaultfd: convert mfill_atomic_pte_copy() to use a folio

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Patch series "userfaultfd: convert userfaultfd functions to use folios",
v6.

This patch series converts several userfaultfd functions to use folios.


This patch (of 6):

Call vma_alloc_folio() directly instead of alloc_page_vma() and convert
page_kaddr to kaddr in mfill_atomic_pte_copy().  Removes several calls to
compound_head().

Link: https://lkml.kernel.org/r/20230410133932.32288-1-zhangpeng362@huawei.com
Link: https://lkml.kernel.org/r/20230410133932.32288-2-zhangpeng362@huawei.com
Signed-off-by: ZhangPeng <zhangpeng362@huawei.com>
Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nanyong Sun <sunnanyong@huawei.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
ZhangPeng 2023-04-10 21:39:27 +08:00 committed by Andrew Morton
parent b4aca54792
commit 07e6d4095c
1 changed files with 16 additions and 16 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

32
mm/userfaultfd.c
View file

@ -135,17 +135,18 @@ static int mfill_atomic_pte_copy(pmd_t *dst_pmd,
uffd_flags_t flags,
struct page **pagep)
{
void *page_kaddr;
void *kaddr;
int ret;
struct page *page;
struct folio *folio;
if (!*pagep) {
ret = -ENOMEM;
page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr);
if (!page)
folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, dst_vma,
dst_addr, false);
if (!folio)
goto out;
page_kaddr = kmap_local_page(page);
kaddr = kmap_local_folio(folio, 0);
/*
* The read mmap_lock is held here. Despite the
* mmap_lock being read recursive a deadlock is still
@ -162,45 +163,44 @@ static int mfill_atomic_pte_copy(pmd_t *dst_pmd,
* and retry the copy outside the mmap_lock.
*/
pagefault_disable();
ret = copy_from_user(page_kaddr,
(const void __user *) src_addr,
ret = copy_from_user(kaddr, (const void __user *) src_addr,
PAGE_SIZE);
pagefault_enable();
kunmap_local(page_kaddr);
kunmap_local(kaddr);
/* fallback to copy_from_user outside mmap_lock */
if (unlikely(ret)) {
ret = -ENOENT;
*pagep = page;
*pagep = &folio->page;
/* don't free the page */
goto out;
}
flush_dcache_page(page);
flush_dcache_folio(folio);
} else {
page = *pagep;
folio = page_folio(*pagep);
*pagep = NULL;
}
/*
* The memory barrier inside __SetPageUptodate makes sure that
* The memory barrier inside __folio_mark_uptodate makes sure that
* preceding stores to the page contents become visible before
* the set_pte_at() write.
*/
__SetPageUptodate(page);
__folio_mark_uptodate(folio);
ret = -ENOMEM;
if (mem_cgroup_charge(page_folio(page), dst_vma->vm_mm, GFP_KERNEL))
if (mem_cgroup_charge(folio, dst_vma->vm_mm, GFP_KERNEL))
goto out_release;
ret = mfill_atomic_install_pte(dst_pmd, dst_vma, dst_addr,
page, true, flags);
&folio->page, true, flags);
if (ret)
goto out_release;
out:
return ret;
out_release:
put_page(page);
folio_put(folio);
goto out;
}