From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Yang Subject: Re: [RFC PATCH] mm: thp: grab the lock before manipulation defer list Date: Sat, 4 Jan 2020 07:39:25 +0800 Message-ID: <20200103233925.GA3678@richard> References: <20200103143407.1089-1-richardw.yang@linux.intel.com> Reply-To: Wei Yang Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: David Rientjes Cc: Wei Yang , hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com, akpm@linux-foundation.org, kirill.shutemov@linux.intel.com, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, yang.shi@linux.alibaba.com On Fri, Jan 03, 2020 at 11:29:06AM -0800, David Rientjes wrote: >On Fri, 3 Jan 2020, Wei Yang wrote: > >> As all the other places, we grab the lock before manipulate the defer list. >> Current implementation may face a race condition. >> >> Fixes: 87eaceb3faa5 ("mm: thp: make deferred split shrinker memcg aware") >> >> Signed-off-by: Wei Yang >> >> --- >> I notice the difference during code reading and just confused about the >> difference. No specific test is done since limited knowledge about cgroup. >> >> Maybe I miss something important? > >The check for !list_empty(page_deferred_list(page)) must certainly be >serialized with doing list_del_init(page_deferred_list(page)). > Hi David Would you mind giving more information? You mean list_empty and list_del_init is atomic? -- Wei Yang Help you, Help me