The patch titled
Subject: mm/mmap/vma_merge: use the proper vma pointer in case 3
has been added to the -mm mm-unstable branch. Its filename is
mm-mmap-vma_merge-use-the-proper-vma-pointer-in-case-3.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mmap-vma_merge-use-the-proper-vma-pointer-in-case-3.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Vlastimil Babka <vbabka@xxxxxxx>
Subject: mm/mmap/vma_merge: use the proper vma pointer in case 3
Date: Thu, 9 Mar 2023 12:12:50 +0100
In case 3 we we use 'next' for everything but vma_pgoff. So use 'next'
for that as well, instead of 'mid', for consistency. Then in case 8 we
have to use 'mid' explicitly, which should also make the intent more
obvious.
Adjust the diagram for cases 1-3 in the comment to match the code - we are
using 'next' for case 3 so mark the range with XXXX instead of NNNN. For
case 2 that's a no-op as the code doesn't touch 'next' or 'mid'. For case
1 it's now wrong but that will be fixed next.
No functional change.
Link: https://lkml.kernel.org/r/20230309111258.24079-3-vbabka@xxxxxxx
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Reviewed-by: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Cc: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
--- a/mm/mmap.c~mm-mmap-vma_merge-use-the-proper-vma-pointer-in-case-3
+++ a/mm/mmap.c
@@ -870,11 +870,11 @@ can_vma_merge_after(struct vm_area_struc
* mmap, brk or case 4 below case 5 below
* mremap move:
* AAAA AAAA
- * PPPP NNNN PPPPNNNNXXXX
+ * PPPP XXXX PPPPNNNNXXXX
* might become might become
* PPPPPPPPPPPP 1 or PPPPPPPPPPPP 6 or
- * PPPPPPPPNNNN 2 or PPPPPPPPXXXX 7 or
- * PPPPNNNNNNNN 3 PPPPXXXXXXXX 8
+ * PPPPPPPPXXXX 2 or PPPPPPPPXXXX 7 or
+ * PPPPXXXXXXXX 3 PPPPXXXXXXXX 8
*
* It is important for case 8 that the vma NNNN overlapping the
* region AAAA is never going to extended over XXXX. Instead XXXX must
@@ -991,9 +991,10 @@ struct vm_area_struct *vma_merge(struct
vma = next; /* case 3 */
vma_start = addr;
vma_end = next->vm_end;
- vma_pgoff = mid->vm_pgoff;
+ vma_pgoff = next->vm_pgoff;
err = 0;
if (mid != next) { /* case 8 */
+ vma_pgoff = mid->vm_pgoff;
remove = mid;
err = dup_anon_vma(next, mid);
}
_
Patches currently in -mm which might be from vbabka@xxxxxxx are
mm-page_alloc-reduce-page-alloc-free-sanity-checks.patch
mm-mmap-vma_merge-use-only-primary-pointers-for-preparing-merge.patch
mm-mmap-vma_merge-use-the-proper-vma-pointer-in-case-3.patch
mm-mmap-vma_merge-use-the-proper-vma-pointers-in-cases-1-and-6.patch
mm-mmap-vma_merge-use-the-proper-vma-pointer-in-case-4.patch
mm-mmap-vma_merge-initialize-mid-and-next-in-natural-order.patch
mm-mmap-vma_merge-set-mid-to-null-if-not-applicable.patch
mm-mmap-vma_merge-rename-adj_next-to-adj_start.patch
mm-mmap-vma_merge-convert-mergeability-checks-to-return-bool.patch
mm-mmap-start-distinguishing-if-vma-can-be-removed-in-mergeability-test.patch
mm-mremap-simplify-vma-expansion-again.patch
