mm: lock newly mapped VMA with corrected ordering

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: 33313a7 ("mm: lock newly mapped VMA which can be modified after it becomes visible") Cc: [email protected] Signed-off-by: Hugh Dickins <[email protected]> Tested-by: Suren Baghdasaryan <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
dzndl · Jul 8, 2023 · 1c7873e · 1c7873e
1 parent 946c6b5
commit 1c7873e
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/mm/mmap.c b/mm/mmap.c
@@ -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) {