+ mm-mremap-fix-dup_anon_vma-in-vma_merge-case-4.patch added to mm-unstable branch

+ mm-mremap-fix-dup_anon_vma-in-vma_merge-case-4.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/mremap: fix dup_anon_vma() in vma_merge() case 4
has been added to the -mm mm-unstable branch.  Its filename is
     mm-mremap-fix-dup_anon_vma-in-vma_merge-case-4.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mremap-fix-dup_anon_vma-in-vma_merge-case-4.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Vlastimil Babka <vbabka@suse.cz>
Subject: mm/mremap: fix dup_anon_vma() in vma_merge() case 4

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 0503ea8f5ba7 ("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: 0503ea8f5ba7 ("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>
---

 mm/mmap.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/mmap.c~mm-mremap-fix-dup_anon_vma-in-vma_merge-case-4
+++ a/mm/mmap.c
@@ -973,7 +973,7 @@ struct vm_area_struct *vma_merge(struct
 			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;
_

Patches currently in -mm which might be from vbabka@suse.cz are

mm-mremap-fix-dup_anon_vma-in-vma_merge-case-4.patch