Commit 183b7a60 authored by Vlastimil Babka's avatar Vlastimil Babka Committed by Andrew Morton
Browse files

mm/mmap/vma_merge: use the proper vma pointer in case 4 

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.

Link: https://lkml.kernel.org/r/20230309111258.24079-5-vbabka@suse.cz


Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
Reviewed-by: default avatarLorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: default avatarLiam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 5ff783f1

mm/mmap.c

+4 −4
Original line number Diff line number Diff line
@@ -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;