linux-kernel - [PATCH v2 1/2] ksm: Initialize the addr only once in rmap_walk

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Message-ID: <20260206175745201sbMJ9Ru8QZsjAo7YMopKS@zte.com.cn>
Date: Fri, 6 Feb 2026 17:57:45 +0800 (CST)
From: <xu.xin16@....com.cn>
To: <xu.xin16@....com.cn>, <david@...nel.org>, <akpm@...ux-foundation.org>
Cc: <chengming.zhou@...ux.dev>, <hughd@...gle.com>, <wang.yaxin@....com.cn>,
        <yang.yang29@....com.cn>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH v2 1/2] ksm: Initialize the addr only once in rmap_walk_ksm

From: xu xin <xu.xin16@....com.cn>

This is a minor performance optimization, especially when there are many
for-loop iterations, because the addr variable doesn’t change across
iterations.

Therefore, it only needs to be initialized once before the loop.

Signed-off-by: xu xin <xu.xin16@....com.cn>
---
 mm/ksm.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/mm/ksm.c b/mm/ksm.c
index 2d89a7c8b4eb..950e122bcbf4 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -3168,6 +3168,8 @@ void rmap_walk_ksm(struct folio *folio, struct rmap_walk_control *rwc)
 		return;
 again:
 	hlist_for_each_entry(rmap_item, &stable_node->hlist, hlist) {
+		/* Ignore the stable/unstable/sqnr flags */
+		const unsigned long addr = rmap_item->address & PAGE_MASK;
 		struct anon_vma *anon_vma = rmap_item->anon_vma;
 		struct anon_vma_chain *vmac;
 		struct vm_area_struct *vma;
@@ -3180,16 +3182,13 @@ void rmap_walk_ksm(struct folio *folio, struct rmap_walk_control *rwc)
 			}
 			anon_vma_lock_read(anon_vma);
 		}
+
 		anon_vma_interval_tree_foreach(vmac, &anon_vma->rb_root,
 					       0, ULONG_MAX) {
-			unsigned long addr;

 			cond_resched();
 			vma = vmac->vma;

-			/* Ignore the stable/unstable/sqnr flags */
-			addr = rmap_item->address & PAGE_MASK;
-
 			if (addr < vma->vm_start || addr >= vma->vm_end)
 				continue;
 			/*
-- 
2.25.1