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mm: lock newly mapped VMA with corrected ordering

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Lockdep is certainly right to complain about

  (&vma->vm_lock->lock){++++}-{3:3}, at: vma_start_write+0x2d/0x3f
                 but task is already holding lock:
  (&mapping->i_mmap_rwsem){+.+.}-{3:3}, at: mmap_region+0x4dc/0x6db

Invert those to the usual ordering.

Fixes: 33313a747e ("mm: lock newly mapped VMA which can be modified after it becomes visible")
Cc: stable@vger.kernel.org
Signed-off-by: Hugh Dickins <hughd@google.com>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2023-07-08 16:04:00 -07:00 committed by Linus Torvalds
parent 946c6b59c5
commit 1c7873e336
1 changed files with 2 additions and 2 deletions
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4
mm/mmap.c
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@ -2809,11 +2809,11 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
if (vma_iter_prealloc(&vmi))
goto close_and_free_vma;
/* Lock the VMA since it is modified after insertion into VMA tree */
vma_start_write(vma);
if (vma->vm_file)
i_mmap_lock_write(vma->vm_file->f_mapping);
/* Lock the VMA since it is modified after insertion into VMA tree */
vma_start_write(vma);
vma_iter_store(&vmi, vma);
mm->map_count++;
if (vma->vm_file) {