From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f72.google.com (mail-pg0-f72.google.com [74.125.83.72]) by kanga.kvack.org (Postfix) with ESMTP id 5799F6B026A for ; Tue, 17 Jan 2017 12:02:18 -0500 (EST) Received: by mail-pg0-f72.google.com with SMTP id t6so109758513pgt.6 for ; Tue, 17 Jan 2017 09:02:18 -0800 (PST) Received: from mail-pg0-x242.google.com (mail-pg0-x242.google.com. [2607:f8b0:400e:c05::242]) by mx.google.com with ESMTPS id u90si25488140pfk.38.2017.01.17.09.02.17 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 17 Jan 2017 09:02:17 -0800 (PST) Received: by mail-pg0-x242.google.com with SMTP id 75so8460419pgf.3 for ; Tue, 17 Jan 2017 09:02:17 -0800 (PST) Date: Tue, 17 Jan 2017 09:02:15 -0800 From: Tejun Heo Subject: Re: [PATCH 2/9] slab: remove synchronous rcu_barrier() call in memcg cache release path Message-ID: <20170117170215.GC28948@mtj.duckdns.org> References: <20170114055449.11044-1-tj@kernel.org> <20170114055449.11044-3-tj@kernel.org> <20170114131939.GA2668@esperanza> <20170114151921.GA32693@mtj.duckdns.org> <20170117000754.GA25218@js1304-P5Q-DELUXE> <20170117163745.GA8352@mtj.duckdns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170117163745.GA8352@mtj.duckdns.org> Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim Cc: Vladimir Davydov , cl@linux.com, penberg@kernel.org, rientjes@google.com, akpm@linux-foundation.org, jsvana@fb.com, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, kernel-team@fb.com On Tue, Jan 17, 2017 at 08:37:45AM -0800, Tejun Heo wrote: > The call sequence doesn't matter. Whether you're using call_rcu() or > rcu_barrier(), you're just waiting for a grace period to pass before > continuing. It doens't give any other ordering guarantees, so the new > code should be equivalent to the old one except for being asynchronous. Oh I was confusing synchronize_rcu() with rcu_barrier(), so you're right, kmem_cache struct needs to stay around for the slab pages to be freed after RCU grace period. Will revise the patch accordingly, thanks. Thanks. -- tejun -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org