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[98.15.154.102]) by smtp.gmail.com with ESMTPSA id h6-20020ac85e06000000b002e1e8a98abbsm17854314qtx.41.2022.03.30.05.08.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Mar 2022 05:08:50 -0700 (PDT) Date: Wed, 30 Mar 2022 08:08:49 -0400 From: Johannes Weiner To: Wei Yang Cc: mhocko@kernel.org, vdavydov.dev@gmail.com, akpm@linux-foundation.org, cgroups@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 2/3] mm/memcg: set pos to prev unconditionally Message-ID: References: <20220225003437.12620-1-richard.weiyang@gmail.com> <20220225003437.12620-3-richard.weiyang@gmail.com> <20220330004750.fx4jr4bnehz4ynpf@master> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220330004750.fx4jr4bnehz4ynpf@master> X-Rspam-User: X-Stat-Signature: 67yf56xe4m5mdaogh33wocnk5jee1o3x Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=cmpxchg-org.20210112.gappssmtp.com header.s=20210112 header.b=kJ787gVx; spf=pass (imf18.hostedemail.com: domain of hannes@cmpxchg.org designates 209.85.219.51 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (policy=none) header.from=cmpxchg.org X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: AFDF41C001B X-HE-Tag: 1648642131-924463 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: On Wed, Mar 30, 2022 at 12:47:50AM +0000, Wei Yang wrote: > Something like this? > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index eed9916cdce5..5d433b79ba47 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -1005,9 +1005,6 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root, > if (!root) > root = root_mem_cgroup; > > - if (prev && !reclaim) > - pos = prev; > - > rcu_read_lock(); > > if (reclaim) { > @@ -1033,6 +1030,8 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root, > */ > (void)cmpxchg(&iter->position, pos, NULL); > } > + } else if (prev) { > + pos = prev; > } > > if (pos) Yep!