diff options
| author | Deepanshu Kartikey <kartikey406@gmail.com> | 2025-09-26 09:02:54 +0530 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-09-28 11:51:34 -0700 |
| commit | dd83609b88986f4add37c0871c3434310652ebd5 (patch) | |
| tree | 889adae741b79ed66f5450a2d54c0d49c652f0d2 /fs/hugetlbfs | |
| parent | fb552b2425cf8f16c9c72229a972d1744b24d855 (diff) | |
hugetlbfs: skip VMAs without shareable locks in hugetlb_vmdelete_list
hugetlb_vmdelete_list() uses trylock to acquire VMA locks during truncate
operations. As per the original design in commit 40549ba8f8e0 ("hugetlb:
use new vma_lock for pmd sharing synchronization"), if the trylock fails
or the VMA has no lock, it should skip that VMA. Any remaining mapped
pages are handled by remove_inode_hugepages() which is called after
hugetlb_vmdelete_list() and uses proper lock ordering to guarantee
unmapping success.
Currently, when hugetlb_vma_trylock_write() returns success (1) for VMAs
without shareable locks, the code proceeds to call unmap_hugepage_range().
This causes assertion failures in huge_pmd_unshare() →
hugetlb_vma_assert_locked() because no lock is actually held:
WARNING: CPU: 1 PID: 6594 Comm: syz.0.28 Not tainted
Call Trace:
hugetlb_vma_assert_locked+0x1dd/0x250
huge_pmd_unshare+0x2c8/0x540
__unmap_hugepage_range+0x6e3/0x1aa0
unmap_hugepage_range+0x32e/0x410
hugetlb_vmdelete_list+0x189/0x1f0
Fix by using goto to ensure locks acquired by trylock are always released,
even when skipping VMAs without shareable locks.
Link: https://lkml.kernel.org/r/20250926033255.10930-1-kartikey406@gmail.com
Fixes: 40549ba8f8e0 ("hugetlb: use new vma_lock for pmd sharing synchronization")
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
Reported-by: syzbot+f26d7c75c26ec19790e7@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=f26d7c75c26ec19790e7
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
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, 9 insertions, 0 deletions
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 3cfdf4091001..94b4d854429e 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -478,6 +478,14 @@ 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); @@ -488,6 +496,7 @@ 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); } } |