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Tue, 10 Mar 2020 15:55:43 -0700 (PDT) Received: from [2620:15c:17:3:3a5:23a7:5e32:4598] ([2620:15c:17:3:3a5:23a7:5e32:4598]) by smtp.gmail.com with ESMTPSA id h22sm47875432pgn.57.2020.03.10.15.55.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Mar 2020 15:55:42 -0700 (PDT) Date: Tue, 10 Mar 2020 15:55:41 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Tetsuo Handa cc: Andrew Morton , Vlastimil Babka , Michal Hocko , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [patch] mm, oom: prevent soft lockup on memcg oom for UP systems In-Reply-To: <0e5ca6ee-d460-db8e-aba2-79aa7a66fad1@I-love.SAKURA.ne.jp> Message-ID: References: <0e5ca6ee-d460-db8e-aba2-79aa7a66fad1@I-love.SAKURA.ne.jp> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII 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, 11 Mar 2020, Tetsuo Handa wrote: > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -2637,6 +2637,8 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc) > > unsigned long reclaimed; > > unsigned long scanned; > > > > + cond_resched(); > > + > > Is this safe for CONFIG_PREEMPTION case? If current thread has realtime priority, > can we guarantee that the OOM victim (well, the OOM reaper kernel thread rather > than the OOM victim ?) gets scheduled? > I think it's the best we can do that immediately solves the issue unless you have another idea in mind? > > switch (mem_cgroup_protected(target_memcg, memcg)) { > > case MEMCG_PROT_MIN: > > /* > > >