linux-kernel - [PATCH] mm/slub: Removing unnecessary variable accesses in the get

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Message-ID: <20250910005957.54108-1-rgbi3307@gmail.com>
Date: Wed, 10 Sep 2025 09:59:56 +0900
From: JaeJoon Jung <rgbi3307@...il.com>
To: cl@...ux.com,
	penberg@...nel.org,
	rientjes@...gle.com,
	iamjoonsoo.kim@....com,
	akpm@...ux-foundation.org,
	vbabka@...e.cz,
	roman.gushchin@...ux.dev,
	42.hyeyoo@...il.com
Cc: JaeJoon Jung <rgbi3307@...il.com>,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	rgbi3307@...er.com
Subject: [PATCH] mm/slub: Removing unnecessary variable accesses in the get_freelist()

It pass a NULL pointer to the freelist_new variable
in the __slab_update_freelist() function so that it don't have to re-fetch
the variable values inside the while loop.
Removing unnecessary variable accesses as shown below
will reduce the code size of the get_freelist() function and make it faster.

Signed-off-by: JaeJoon Jung <rgbi3307@...il.com>
---
 mm/slub.c | 21 ++++-----------------
 1 file changed, 4 insertions(+), 17 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index d257141896c9..2e305a17a9d7 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3654,27 +3654,14 @@ __update_cpu_freelist_fast(struct kmem_cache *s,
  */
 static inline void *get_freelist(struct kmem_cache *s, struct slab *slab)
 {
-	struct slab new;
-	unsigned long counters;
-	void *freelist;
-
 	lockdep_assert_held(this_cpu_ptr(&s->cpu_slab->lock));
 
-	do {
-		freelist = slab->freelist;
-		counters = slab->counters;
-
-		new.counters = counters;
-
-		new.inuse = slab->objects;
-		new.frozen = freelist != NULL;
-
-	} while (!__slab_update_freelist(s, slab,
-		freelist, counters,
-		NULL, new.counters,
+	while (!__slab_update_freelist(s, slab,
+		slab->freelist, slab->counters,
+		NULL, slab->counters,
 		"get_freelist"));
 
-	return freelist;
+	return slab->freelist;
 }
 
 /*
-- 
2.43.0