+ mm-mmap-add-case-9-in-vma_merge.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/mmap: Add case 9 in vma_merge()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-mmap-add-case-9-in-vma_merge.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mmap-add-case-9-in-vma_merge.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: Yajun Deng <yajun.deng@linux.dev>
Subject: mm/mmap: Add case 9 in vma_merge()
Date: Sun, 18 Feb 2024 16:50:28 +0800

If the prev vma exists and the end is less than the end of prev, we
can return NULL immediately. This reduces unnecessary operations.

Link: https://lkml.kernel.org/r/20240218085028.3294332-1-yajun.deng@linux.dev
Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/mmap.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/mm/mmap.c~mm-mmap-add-case-9-in-vma_merge
+++ a/mm/mmap.c
@@ -827,7 +827,7 @@ can_vma_merge_after(struct vm_area_struc
  *
  *     ****             ****                   ****
  *    PPPPPPNNNNNN    PPPPPPNNNNNN       PPPPPPCCCCCC
- *    cannot merge    might become       might become
+ *    cannot merge 9  might become       might become
  *                    PPNNNNNNNNNN       PPPPPPPPPPCC
  *    mmap, brk or    case 4 below       case 5 below
  *    mremap move:
@@ -890,6 +890,9 @@ static struct vm_area_struct
 	if (vm_flags & VM_SPECIAL)
 		return NULL;
 
+	if (prev && end < prev->vm_end) /* case 9 */
+		return NULL;
+
 	/* Does the input range span an existing VMA? (cases 5 - 8) */
 	curr = find_vma_intersection(mm, prev ? prev->vm_end : 0, end);
 
_

Patches currently in -mm which might be from yajun.deng@linux.dev are

mm-mmap-simplify-vma-link-and-unlink.patch
mm-mmap-introduce-vma_set_range.patch
mm-mmap-use-sz_8k-128k-helper-macro.patch
mm-mmap-pass-vma-to-vma_merge.patch
mm-mmap-add-case-9-in-vma_merge.patch