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Wed, 27 May 2026 13:48:08 -0700 (PDT) From: Johannes Weiner To: Andrew Morton Cc: David Hildenbrand , Lorenzo Stoakes , Shakeel Butt , Michal Hocko , Dave Chinner , Roman Gushchin , Muchun Song , Qi Zheng , Yosry Ahmed , Zi Yan , "Liam R . Howlett" , Usama Arif , Kiryl Shutsemau , Vlastimil Babka , Kairui Song , Mikhail Zaslonko , Vasily Gorbik , Baolin Wang , Barry Song , Dev Jain , Lance Yang , Nico Pache , Ryan Roberts , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 2/9] mm: list_lru: lock_list_lru_of_memcg() cannot return NULL if !skip_empty Date: Wed, 27 May 2026 16:45:09 -0400 Message-ID: <20260527204757.2544958-3-hannes@cmpxchg.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260527204757.2544958-1-hannes@cmpxchg.org> References: <20260527204757.2544958-1-hannes@cmpxchg.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 393D214000F X-Stat-Signature: fzsajk7o4okf5ewf14rt5dc6mfwdjui1 X-HE-Tag: 1779914890-591107 X-HE-Meta: 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 wlqtnv53 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: skip_empty is only for the shrinker to abort and skip a list that's empty or whose cgroup is being deleted. For list additions and deletions, the cgroup hierarchy is walked upwards until a valid list_lru head is found, or it will fall back to the node list. Acquiring the lock won't fail. Remove the NULL checks in those callers. Reviewed-by: David Hildenbrand (Arm) Acked-by: Shakeel Butt Reviewed-by: Lorenzo Stoakes (Oracle) Signed-off-by: Johannes Weiner Reviewed-by: Liam R. Howlett (Oracle) --- mm/list_lru.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/mm/list_lru.c b/mm/list_lru.c index 45d1b97737ea..77999ed78fa5 100644 --- a/mm/list_lru.c +++ b/mm/list_lru.c @@ -165,8 +165,6 @@ bool list_lru_add(struct list_lru *lru, struct list_head *item, int nid, struct list_lru_one *l; l = lock_list_lru_of_memcg(lru, nid, &memcg, false, false); - if (!l) - return false; if (list_empty(item)) { list_add_tail(item, &l->list); /* @@ -208,9 +206,8 @@ bool list_lru_del(struct list_lru *lru, struct list_head *item, int nid, { struct list_lru_node *nlru = &lru->node[nid]; struct list_lru_one *l; + l = lock_list_lru_of_memcg(lru, nid, &memcg, false, false); - if (!l) - return false; if (!list_empty(item)) { list_del_init(item); l->nr_items--; -- 2.54.0