linux-kernel - [PATCH 2/2] [PATCH 2/2] mm: add merging after mremap resize

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Message-Id: <20220527104810.24736-3-matenajakub@gmail.com>
Date:   Fri, 27 May 2022 12:48:10 +0200
From:   Jakub Matěna <matenajakub@...il.com>
To:     akpm@...ux-foundation.org
Cc:     linux-mm@...ck.org, patches@...ts.linux.dev,
        linux-kernel@...r.kernel.org, vbabka@...e.cz, mhocko@...nel.org,
        mgorman@...hsingularity.net, willy@...radead.org,
        liam.howlett@...cle.com, hughd@...gle.com, kirill@...temov.name,
        riel@...riel.com, rostedt@...dmis.org, peterz@...radead.org,
        Jakub Matěna <matenajakub@...il.com>
Subject: [PATCH 2/2] [PATCH 2/2] mm: add merging after mremap resize

When mremap call results in expansion, it might be possible to merge the
VMA with the next VMA which might become adjacent. This patch adds
vma_merge call after the expansion is done to try and merge.

Signed-off-by: Jakub Matěna <matenajakub@...il.com>
---
 mm/mremap.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/mm/mremap.c b/mm/mremap.c
index 303d3290b938..c41237e62156 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -9,6 +9,7 @@
  */
 
 #include <linux/mm.h>
+#include <linux/mm_inline.h>
 #include <linux/hugetlb.h>
 #include <linux/shm.h>
 #include <linux/ksm.h>
@@ -1022,8 +1023,11 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
 				}
 			}
 
-			if (vma_adjust(vma, vma->vm_start, addr + new_len,
-				       vma->vm_pgoff, NULL)) {
+			vma = vma_merge(mm, vma, addr + old_len, addr + new_len,
+					vma->vm_flags, vma->anon_vma, vma->vm_file,
+					vma->vm_pgoff + (old_len >> PAGE_SHIFT), vma_policy(vma),
+					vma->vm_userfaultfd_ctx, anon_vma_name(vma));
+			if (!vma) {
 				vm_unacct_memory(pages);
 				ret = -ENOMEM;
 				goto out;
-- 
2.35.1