From:   Vlastimil Babka <vbabka@suse.cz>
To:     linux-mm@kvack.org, "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc:     linux-kernel@vger.kernel.org, patches@lists.linux.dev,
        maple-tree@lists.infradead.org, Vlastimil Babka <vbabka@suse.cz>
Subject: [RFC 05/11] mm/mmap/vma_merge: use the proper vma pointer in case 4
Date:   Fri, 24 Feb 2023 11:00:16 +0100
Message-Id: <20230224100022.11268-6-vbabka@suse.cz>
In-Reply-To: <20230224100022.11268-1-vbabka@suse.cz>
References: <20230224100022.11268-1-vbabka@suse.cz>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Almost all cases now use the 'next' pointer for the vma following
the merged area, and the cases diagram shows it as XXXX. Case 4 is
different as it uses 'mid' and NNNN, so change it for consistency. No
functional change.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
 mm/mmap.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 704afa278a98..1e4be7174964 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -851,9 +851,9 @@ can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
  * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
  *
  *     AAAA             AAAA                   AAAA
- *    PPPPPPNNNNNN    PPPPPPNNNNNN       PPPPPPNNNNNN
+ *    PPPPPPNNNNNN    PPPPPPXXXXXX       PPPPPPNNNNNN
  *    cannot merge    might become       might become
- *                    PPNNNNNNNNNN       PPPPPPPPPPNN
+ *                    PPXXXXXXXXXX       PPPPPPPPPPNN
  *    mmap, brk or    case 4 below       case 5 below
  *    mremap move:
  *                        AAAA               AAAA
@@ -972,9 +972,9 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm,
 		res = next;
 		if (prev && addr < prev->vm_end) {	/* case 4 */
 			vma_end = addr;
-			adjust = mid;
+			adjust = next;
 			adj_next = -(prev->vm_end - addr);
-			err = dup_anon_vma(mid, prev);
+			err = dup_anon_vma(next, prev);
 		} else {
 			vma = next;			/* case 3 */
 			vma_start = addr;
-- 
2.39.2