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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1747248167; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tl4rUg93LkTokTk1IS4m9ISxrd6enFA07YnhN9En2KU=; b=XsH+sSP2IqgV4b7JFzKmne3RJ7B8fs6sll5nB5jaO2ynnf01GgAFSgEyNXGG86e9Z7QQ1C xAVYpXslEoie+4agb0gtbili30uXYuaShK5I8zmCyUoS39PXhQWaMMqSpDmDEFLEr7kO7A tKA3XPMFfwrhihunQK+imHxFUbmwrx0= From: Shakeel Butt To: Andrew Morton Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Vlastimil Babka , Alexei Starovoitov , Sebastian Andrzej Siewior , Harry Yoo , Yosry Ahmed , bpf@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team Subject: [PATCH v2 6/7] memcg: no stock lock for cpu hot-unplug Date: Wed, 14 May 2025 11:41:57 -0700 Message-ID: <20250514184158.3471331-7-shakeel.butt@linux.dev> In-Reply-To: <20250514184158.3471331-1-shakeel.butt@linux.dev> References: <20250514184158.3471331-1-shakeel.butt@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Stat-Signature: 6cwf5aq7xff7k6nkymnd85xbrpomq343 X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 4E95F40005 X-HE-Tag: 1747248169-711053 X-HE-Meta: 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 8RbSkgOE weNzFRmLGNAQaIIUpwaBRIEsd1u8zHNcXfcXGpY4EeKxVcn8/a6d7kKQbq3gwDiCLlrGxw75mIuJzXRMm3wB09itid5Y+EJwQufzNh/LCwQYmopQl4Kp9MdChBB3rxug2+ISTMIocNXl6tphfrCxop/uxnWl4JnrSQzXZRqF/AlCwCbg= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Previously on the cpu hot-unplug, the kernel would call drain_obj_stock() with objcg local lock. However local lock was not needed as the stock which was accessed belongs to a dead cpu but we kept it there to disable irqs as drain_obj_stock() may call mod_objcg_mlstate() which required irqs disabled. However there is no need to disable irqs now for mod_objcg_mlstate(), so we can remove the local lock altogether from cpu hot-unplug path. Signed-off-by: Shakeel Butt Acked-by: Vlastimil Babka --- mm/memcontrol.c | 11 +---------- 1 file changed, 1 insertion(+), 10 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 1071db0b1df8..04d756be708b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2025,17 +2025,8 @@ void drain_all_stock(struct mem_cgroup *root_memcg) static int memcg_hotplug_cpu_dead(unsigned int cpu) { - struct obj_stock_pcp *obj_st; - unsigned long flags; - - obj_st = &per_cpu(obj_stock, cpu); - - /* drain_obj_stock requires objstock.lock */ - local_lock_irqsave(&obj_stock.lock, flags); - drain_obj_stock(obj_st); - local_unlock_irqrestore(&obj_stock.lock, flags); - /* no need for the local lock */ + drain_obj_stock(&per_cpu(obj_stock, cpu)); drain_stock_fully(&per_cpu(memcg_stock, cpu)); return 0; -- 2.47.1