linux-kernel - [RFC PATCH 01/10] memcg: remove root memcg check from refill

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Message-ID: <20250314061511.1308152-2-shakeel.butt@linux.dev>
Date: Thu, 13 Mar 2025 23:15:02 -0700
From: Shakeel Butt <shakeel.butt@...ux.dev>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Johannes Weiner <hannes@...xchg.org>,
	Michal Hocko <mhocko@...nel.org>,
	Roman Gushchin <roman.gushchin@...ux.dev>,
	Muchun Song <muchun.song@...ux.dev>,
	Vlastimil Babka <vbabka@...e.cz>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	linux-mm@...ck.org,
	cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Meta kernel team <kernel-team@...a.com>
Subject: [RFC PATCH 01/10] memcg: remove root memcg check from refill_stock

refill_stock can not be called with root memcg, so there is no need to
check it.

Signed-off-by: Shakeel Butt <shakeel.butt@...ux.dev>
---
 mm/memcontrol.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b29433eb17fa..c09a32e93d39 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1883,6 +1883,7 @@ static void __refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
 		drain_stock(stock);
 }
 
+/* Should never be called with root_mem_cgroup. */
 static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
 {
 	unsigned long flags;
@@ -1892,8 +1893,6 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
 		 * In case of unlikely failure to lock percpu stock_lock
 		 * uncharge memcg directly.
 		 */
-		if (mem_cgroup_is_root(memcg))
-			return;
 		page_counter_uncharge(&memcg->memory, nr_pages);
 		if (do_memsw_account())
 			page_counter_uncharge(&memcg->memsw, nr_pages);
-- 
2.47.1