linux-kernel - [PATCH 2/2] mm/damon/vaddr: remove comparison between mm and last

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Date:   Fri, 26 Aug 2022 16:31:18 +0800
From:   xiakaixu1987@...il.com
To:     sj@...nel.org, akpm@...ux-foundation.org
Cc:     damon@...ts.linux.dev, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Kaixu Xia <kaixuxia@...cent.com>
Subject: [PATCH 2/2] mm/damon/vaddr: remove comparison between mm and last_mm when checking region accesses

From: Kaixu Xia <kaixuxia@...cent.com>

The damon regions that belong to the same damon target have the same
'struct mm_struct *mm', so it's unnecessary to compare the mm and last_mm
objects among the damon regions in one damon target when checking accesses.

Signed-off-by: Kaixu Xia <kaixuxia@...cent.com>
---
 mm/damon/vaddr.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
index c8c2f306bb6d..db9d0ab37a52 100644
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -534,14 +534,13 @@ static bool damon_va_young(struct mm_struct *mm, unsigned long addr,
  */
 static void __damon_va_check_access(struct mm_struct *mm, struct damon_region *r)
 {
-	static struct mm_struct *last_mm;
 	static unsigned long last_addr;
 	static unsigned long last_page_sz = PAGE_SIZE;
 	static bool last_accessed;
 
 	/* If the region is in the last checked page, reuse the result */
-	if (mm == last_mm && (ALIGN_DOWN(last_addr, last_page_sz) ==
-				ALIGN_DOWN(r->sampling_addr, last_page_sz))) {
+	if (ALIGN_DOWN(last_addr, last_page_sz) ==
+				ALIGN_DOWN(r->sampling_addr, last_page_sz)) {
 		if (last_accessed)
 			r->nr_accesses++;
 		return;
@@ -551,7 +550,6 @@ static void __damon_va_check_access(struct mm_struct *mm, struct damon_region *r
 	if (last_accessed)
 		r->nr_accesses++;
 
-	last_mm = mm;
 	last_addr = r->sampling_addr;
 }
 
-- 
2.27.0