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mm/mremap: fix dup_anon_vma() in vma_merge() case 4

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In case 4, we are shrinking 'prev' (PPPP in the comment) and expanding
'mid' (NNNN).  So we need to make sure 'mid' clones the anon_vma from
'prev', if it doesn't have any.  After commit 0503ea8f5b ("mm/mmap:
remove __vma_adjust()") we can fail to do that due to wrong parameters for
dup_anon_vma().  The call is a no-op because res == next, adjust == mid
and mid == next.  Fix it.

Link: https://lkml.kernel.org/r/ad91d62b-37eb-4b73-707a-3c45c9e16256@suse.cz
Fixes: 0503ea8f5b ("mm/mmap: remove __vma_adjust()")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Vlastimil Babka 2023-02-27 17:00:14 -08:00 committed by Andrew Morton
parent 1ec35eadc3
commit 4c67599678
1 changed files with 1 additions and 1 deletions
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2
mm/mmap.c
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@ -973,7 +973,7 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm,
vma_end = addr;
adjust = mid;
adj_next = -(vma->vm_end - addr);
err = dup_anon_vma(res, adjust);
err = dup_anon_vma(adjust, prev);
} else {
vma = next; /* case 3 */
vma_start = addr;