diff options
| author | Deepanshu Kartikey <kartikey406@gmail.com> | 2025-10-14 17:03:44 +0530 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-10-21 15:46:17 -0700 |
| commit | cec944dd329fbefee907da95c298719d900d4787 (patch) | |
| tree | 0cbdc0014b445da53b6577eed96684d2e198f9ba /fs/hugetlbfs | |
| parent | 4ba5a8a7faa647ada8eae61a36517cf369f5bbe4 (diff) | |
hugetlbfs: move lock assertions after early returns in huge_pmd_unshare()
When hugetlb_vmdelete_list() processes VMAs during truncate operations, it
may encounter VMAs where huge_pmd_unshare() is called without the required
shareable lock. This triggers an assertion failure in
hugetlb_vma_assert_locked().
The previous fix in commit dd83609b8898 ("hugetlbfs: skip VMAs without
shareable locks in hugetlb_vmdelete_list") skipped entire VMAs without
shareable locks to avoid the assertion. However, this prevented pages
from being unmapped and freed, causing a regression in
fallocate(PUNCH_HOLE) operations where pages were not freed immediately,
as reported by Mark Brown.
Instead of checking locks in the caller or skipping VMAs, move the lock
assertions in huge_pmd_unshare() to after the early return checks. The
assertions are only needed when actual PMD unsharing work will be
performed. If the function returns early because sz != PMD_SIZE or the
PMD is not shared, no locks are required and assertions should not fire.
This approach reverts the VMA skipping logic from commit dd83609b8898
("hugetlbfs: skip VMAs without shareable locks in hugetlb_vmdelete_list")
while moving the assertions to avoid the assertion failure, keeping all
the logic within huge_pmd_unshare() itself and allowing page unmapping and
freeing to proceed for all VMAs.
Link: https://lkml.kernel.org/r/20251014113344.21194-1-kartikey406@gmail.com
Fixes: dd83609b8898 ("hugetlbfs: skip VMAs without shareable locks in hugetlb_vmdelete_list")
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
Reported-by: <syzbot+f26d7c75c26ec19790e7@syzkaller.appspotmail.com>
Reported-by: Mark Brown <broonie@kernel.org>
Closes: https://syzkaller.appspot.com/bug?extid=f26d7c75c26ec19790e7
Suggested-by: David Hildenbrand <david@redhat.com>
Suggested-by: Oscar Salvador <osalvador@suse.de>
Tested-by: <syzbot+f26d7c75c26ec19790e7@syzkaller.appspotmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'fs/hugetlbfs')
| -rw-r--r-- | fs/hugetlbfs/inode.c | 9 |
1 files changed, 0 insertions, 9 deletions
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 9c94ed8c3ab0..f42548ee9083 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -478,14 +478,6 @@ hugetlb_vmdelete_list(struct rb_root_cached *root, pgoff_t start, pgoff_t end, if (!hugetlb_vma_trylock_write(vma)) continue; - /* - * Skip VMAs without shareable locks. Per the design in commit - * 40549ba8f8e0, these will be handled by remove_inode_hugepages() - * called after this function with proper locking. - */ - if (!__vma_shareable_lock(vma)) - goto skip; - v_start = vma_offset_start(vma, start); v_end = vma_offset_end(vma, end); @@ -496,7 +488,6 @@ hugetlb_vmdelete_list(struct rb_root_cached *root, pgoff_t start, pgoff_t end, * vmas. Therefore, lock is not held when calling * unmap_hugepage_range for private vmas. */ -skip: hugetlb_vma_unlock_write(vma); } } |