[PATCH] mm/mmap.c: make vma_merge() comment more easy to understand

From: Wei Yang
Date: Tue Oct 29 2019 - 21:25:34 EST


Case 1/6, 2/7 and 3/8 have the same pattern and we handle them in the
same logic.

Rearrange the comment to make it a little easy for audience to
understand.

Signed-off-by: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>
---
mm/mmap.c | 21 ++++++++++++---------
1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index a7d8c84d19b7..d485100f9d29 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1116,15 +1116,18 @@ can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
* the area passed down from mprotect_fixup, never extending beyond one
* vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
*
- * AAAA AAAA AAAA AAAA
- * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
- * cannot merge might become might become might become
- * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
- * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
- * mremap move: PPPPXXXXXXXX 8
- * AAAA
- * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
- * might become case 1 below case 2 below case 3 below
+ * AAAA AAAA AAAA
+ * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN
+ * cannot merge might become might become
+ * PPNNNNNNNNNN PPPPPPPPPPNN
+ * mmap, brk or case 4 below case 5 below
+ * mremap move:
+ * AAAA AAAA
+ * PPPP NNNN PPPPNNNNXXXX
+ * might become might become
+ * PPPPPPPPPPPP 1 or PPPPPPPPPPPP 6 or
+ * PPPPPPPPNNNN 2 or PPPPPPPPXXXX 7 or
+ * PPPPNNNNNNNN 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
--
2.17.1