linux-kernel - [PATCH] mm/mmap.c: remove a never trigger warning in __vma

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Date:   Thu, 12 Sep 2019 14:31:26 +0800
From:   Wei Yang <richardw.yang@...ux.intel.com>
To:     akpm@...ux-foundation.org, vbabka@...e.cz,
        yang.shi@...ux.alibaba.com
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Wei Yang <richardw.yang@...ux.intel.com>
Subject: [PATCH] mm/mmap.c: remove a never trigger warning in __vma_adjust()

The upper level of "if" makes sure (end >= next->vm_end), which means
there are only two possibilities:

   1) end == next->vm_end
   2) end > next->vm_end

remove_next is assigned to be (1 + end > next->vm_end). This means if
remove_next is 1, end must equal to next->vm_end.

The VM_WARN_ON will never trigger.

Signed-off-by: Wei Yang <richardw.yang@...ux.intel.com>
---
 mm/mmap.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 907939690a30..18ef68f00f51 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -738,8 +738,6 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
 				remove_next = 1 + (end > next->vm_end);
 				VM_WARN_ON(remove_next == 2 &&
 					   end != next->vm_next->vm_end);
-				VM_WARN_ON(remove_next == 1 &&
-					   end != next->vm_end);
 				/* trim end to next, for case 6 first pass */
 				end = next->vm_end;
 			}
-- 
2.17.1