linux-kernel - [PATCH 2/2] mm/mmap: leverage vma_rb_erase_ignore() to implement vma_rb

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Message-Id: <20200809232057.23477-2-richard.weiyang@linux.alibaba.com>
Date:   Mon, 10 Aug 2020 07:20:57 +0800
From:   Wei Yang <richard.weiyang@...ux.alibaba.com>
To:     akpm@...ux-foundation.org
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Wei Yang <richard.weiyang@...ux.alibaba.com>
Subject: [PATCH 2/2] mm/mmap: leverage vma_rb_erase_ignore() to implement vma_rb_erase()

These two functions share the same logic except ignore a different vma.

Let's reuse the code.

Signed-off-by: Wei Yang <richard.weiyang@...ux.alibaba.com>
---
 mm/mmap.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index ec780925da94..90b1298d4222 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -474,8 +474,12 @@ static __always_inline void vma_rb_erase_ignore(struct vm_area_struct *vma,
 {
 	/*
 	 * All rb_subtree_gap values must be consistent prior to erase,
-	 * with the possible exception of the "next" vma being erased if
-	 * next->vm_start was reduced.
+	 * with the possible exception of
+	 *
+	 * a. the "next" vma being erased if next->vm_start was reduced in
+	 *    __vma_adjust() -> __vma_unlink()
+	 * b. the vma being erased in detach_vmas_to_be_unmapped() ->
+	 *    vma_rb_erase()
 	 */
 	validate_mm_rb(root, ignore);
 
@@ -485,13 +489,7 @@ static __always_inline void vma_rb_erase_ignore(struct vm_area_struct *vma,
 static __always_inline void vma_rb_erase(struct vm_area_struct *vma,
 					 struct rb_root *root)
 {
-	/*
-	 * All rb_subtree_gap values must be consistent prior to erase,
-	 * with the possible exception of the vma being erased.
-	 */
-	validate_mm_rb(root, vma);
-
-	__vma_rb_erase(vma, root);
+	vma_rb_erase_ignore(vma, root, vma);
 }
 
 /*
-- 
2.20.1 (Apple Git-117)