From 5d42ab293f5181609ea18f1f2ab85cd4cfc8efb2 Mon Sep 17 00:00:00 2001 From: Wei Yang Date: Sat, 30 Nov 2019 17:57:39 -0800 Subject: [PATCH] mm/mmap.c: make vma_merge() comment more easy to understand 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. Link: http://lkml.kernel.org/r/20191030012445.16944-1-richardw.yang@linux.intel.com Signed-off-by: Wei Yang Cc: Mike Rapoport Cc: Will Deacon Cc: Michal Hocko Cc: Catalin Marinas Cc: Andrea Arcangeli Cc: Jann Horn Cc: Darrick J. Wong Cc: Steve Capper Cc: Michel Lespinasse Cc: Dave Hansen Cc: Yangtao Li Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/mmap.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index b9d0c2f3f6bf..9c648524e4dc 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1091,15 +1091,18 @@ 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