[PATCH] mm/vma: check retry_merge only for new vma case

[Wei Yang <richard.weiyang@xxxxxxxxx>]

Current code logic looks like this:

__mmap_region()
  vma = vma_merge_new_range(&vmg)
  if (!vma)
    __mmap_new_vma(&map, &vma)
      __mmap_new_file_vma(map, vma)
        map->retry_merge = xxx               --- (1)
  if (map.retry_merge)
    vma_merge_existing_range(vmg, &map, vma)

Location (1) is the only place where map.retry_merge is set, this means
it is not necessary to check it if already merged with adjacent vma.

Let's move the check and following operation into new vma case.

Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
CC: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
CC: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
CC: Vlastimil Babka <vbabka@xxxxxxx>
CC: Jann Horn <jannh@xxxxxxxxxx>
---
 mm/vma.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/mm/vma.c b/mm/vma.c
index 8a454a7bbc80..80b1bd404f23 100644
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -2456,14 +2456,14 @@ unsigned long __mmap_region(struct file *file, unsigned long addr,
 		error = __mmap_new_vma(&map, &vma);
 		if (error)
 			goto unacct_error;
-	}
 
-	/* If flags changed, we might be able to merge, so try again. */
-	if (map.retry_merge) {
-		VMG_MMAP_STATE(vmg, &map, vma);
+		/* If flags changed, we might be able to merge, so try again. */
+		if (map.retry_merge) {
+			VMG_MMAP_STATE(vmg, &map, vma);
 
-		vma_iter_config(map.vmi, map.addr, map.end);
-		vma_merge_existing_range(&vmg);
+			vma_iter_config(map.vmi, map.addr, map.end);
+			vma_merge_existing_range(&vmg);
+		}
 	}
 
 	__mmap_complete(&map, vma);
-- 
2.34.1