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01d89b93e1
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Peter Xu 01d89b93e1 mm/gup: fix hugepd handling in hugetlb rework 
Commit a12083d721 added hugepd handling for gup-slow, reusing gup-fast
functions.  follow_hugepd() correctly took the vma pointer in, however
didn't pass it over into the lower functions, which was overlooked.

The issue is gup_fast_hugepte() uses the vma pointer to make the correct
decision on whether an unshare is needed for a FOLL_PIN|FOLL_LONGTERM. 
Now without vma ponter it will constantly return "true" (needs an unshare)
for a page cache, even though in the SHARED case it will be wrong to
unshare.

The other problem is, even if an unshare is needed, it now returns 0
rather than -EMLINK, which will not trigger a follow up FAULT_FLAG_UNSHARE
fault.  That will need to be fixed too when the unshare is wanted.

gup_longterm test didn't expose this issue in the past because it didn't
yet test R/O unshare in this case, another separate patch will enable that
in future tests.

Fix it by passing vma correctly to the bottom, rename gup_fast_hugepte()
back to gup_hugepte() as it is shared between the fast/slow paths, and
also allow -EMLINK to be returned properly by gup_hugepte() even though
gup-fast will take it the same as zero.

Link: https://lkml.kernel.org/r/20240430131303.264331-1-peterx@redhat.com
Fixes: a12083d721 ("mm/gup: handle hugepd for follow_page()")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reported-by: David Hildenbrand <david@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-05-07 10:37:01 -07:00
arch mm: fix race between __split_huge_pmd_locked() and GUP-fast 2024-05-07 10:37:00 -07:00
block block-6.9-20240412 2024-04-12 10:22:33 -07:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto This push fixes a regression that broke iwd as well as a divide by 2024-03-25 10:48:23 -07:00
Documentation mm: fix race between __split_huge_pmd_locked() and GUP-fast 2024-05-07 10:37:00 -07:00
drivers dax/bus.c: use the right locking mode (read vs write) in size_show 2024-05-07 10:37:01 -07:00
fs mm: simplify thp_vma_allowable_order 2024-05-05 17:53:53 -07:00
include memcg: use proper type for mod_memcg_state 2024-05-07 10:37:00 -07:00
init mm: introduce slabobj_ext to support slab object extensions 2024-04-25 20:55:51 -07:00
io_uring mm: switch mm->get_unmapped_area() to a flag 2024-04-25 20:56:25 -07:00
ipc sysctl changes for v6.9-rc1 2024-03-18 14:59:13 -07:00
kernel mm/treewide: rename CONFIG_HAVE_FAST_GUP to CONFIG_HAVE_GUP_FAST 2024-04-25 20:56:41 -07:00
lib xarray: inline xas_descend to improve performance 2024-05-05 17:53:38 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/gup: fix hugepd handling in hugetlb rework 2024-05-07 10:37:01 -07:00
net mm: change inlined allocation helpers to account at the call site 2024-04-25 20:55:59 -07:00
rust rust: add a rust helper for krealloc() 2024-04-25 20:55:55 -07:00
samples Tracing updates for 6.9: 2024-03-18 15:11:44 -07:00
scripts lib: add allocation tagging support for memory allocation profiling 2024-04-25 20:55:52 -07:00
security mm: init_mlocked_on_free_v3 2024-04-25 20:56:29 -07:00
sound fix missing vmalloc.h includes 2024-04-25 20:55:49 -07:00
tools selftests: mm: gup_longterm: test unsharing logic when R/O pinning 2024-05-07 10:37:01 -07:00
usr Kbuild updates for v6.8 2024-01-18 17:57:07 -08:00
virt mm: pass VMA instead of MM to follow_pte() 2024-05-05 17:53:27 -07:00
.clang-format clang-format: Update with v6.7-rc4's for_each macro list 2023-12-08 23:54:38 +01:00
.cocciconfig
.editorconfig Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: create a list of all built DTB files 2024-02-19 18:20:39 +09:00
.mailmap MAINTAINERS: update Naoya Horiguchi's email address 2024-04-16 15:39:51 -07:00
.rustfmt.toml
COPYING
CREDITS MAINTAINERS: Drop Gustavo Pimentel as PCI DWC Maintainer 2024-03-27 13:41:02 -05:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig
MAINTAINERS MAINTAINERS: add entries for code tagging and memory allocation profiling 2024-04-25 20:55:58 -07:00
Makefile Linux 6.9-rc4 2024-04-14 13:38:39 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.