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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 4/9] mm: list_lru: move list dead check to lock_list_lru_of_memcg() Date: Wed, 27 May 2026 16:45:11 -0400 Message-ID: <20260527204757.2544958-5-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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Only the MEMCG variant of lock_list_lru() needs to check if there is a race with cgroup deletion and list reparenting. Move the check to the caller, so that the next patch can unify the lock_list_lru() variants. 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 | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-) diff --git a/mm/list_lru.c b/mm/list_lru.c index 5497034e80f3..7d0523e44010 100644 --- a/mm/list_lru.c +++ b/mm/list_lru.c @@ -68,17 +68,12 @@ list_lru_from_memcg_idx(struct list_lru *lru, int nid, int idx) return &lru->node[nid].lru; } -static inline bool lock_list_lru(struct list_lru_one *l, bool irq) +static inline void lock_list_lru(struct list_lru_one *l, bool irq) { if (irq) spin_lock_irq(&l->lock); else spin_lock(&l->lock); - if (unlikely(READ_ONCE(l->nr_items) == LONG_MIN)) { - unlock_list_lru(l, irq); - return false; - } - return true; } static inline struct list_lru_one * @@ -90,9 +85,13 @@ lock_list_lru_of_memcg(struct list_lru *lru, int nid, rcu_read_lock(); again: l = list_lru_from_memcg_idx(lru, nid, memcg_kmem_id(*memcg)); - if (likely(l) && lock_list_lru(l, irq)) { - rcu_read_unlock(); - return l; + if (likely(l)) { + lock_list_lru(l, irq); + if (likely(READ_ONCE(l->nr_items) != LONG_MIN)) { + rcu_read_unlock(); + return l; + } + unlock_list_lru(l, irq); } /* * Caller may simply bail out if raced with reparenting or -- 2.54.0