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Subject: [PATCH v2 2/2] [PATCH 2/2] mm: add merging after mremap resize
Date:   Fri, 27 May 2022 23:17:08 +0200
Message-Id: <20220527211708.839033-3-matenajakub@gmail.com>
In-Reply-To: <20220527211708.839033-1-matenajakub@gmail.com>
References: <20220527211708.839033-1-matenajakub@gmail.com>
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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@gmail.com>
---
 mm/mremap.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/mm/mremap.c b/mm/mremap.c
index 303d3290b938..21dfa15e8200 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>
@@ -23,6 +24,7 @@
 #include <linux/mmu_notifier.h>
 #include <linux/uaccess.h>
 #include <linux/userfaultfd_k.h>
+#include <linux/mempolicy.h>
 
 #include <asm/cacheflush.h>
 #include <asm/tlb.h>
@@ -1022,8 +1024,11 @@ 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