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Wed, 30 Nov 2022 13:15:06 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id V0ynJVpXh2OuVwAAMHmgww (envelope-from ); Wed, 30 Nov 2022 13:15:06 +0000 Date: Wed, 30 Nov 2022 14:15:06 +0100 From: Michal Hocko To: chengkaitao Cc: tj@kernel.org, lizefan.x@bytedance.com, hannes@cmpxchg.org, corbet@lwn.net, roman.gushchin@linux.dev, shakeelb@google.com, akpm@linux-foundation.org, songmuchun@bytedance.com, cgel.zte@gmail.com, ran.xiaokai@zte.com.cn, viro@zeniv.linux.org.uk, zhengqi.arch@bytedance.com, ebiederm@xmission.com, Liam.Howlett@oracle.com, chengzhihao1@huawei.com, haolee.swjtu@gmail.com, yuzhao@google.com, willy@infradead.org, vasily.averin@linux.dev, vbabka@suse.cz, surenb@google.com, sfr@canb.auug.org.au, mcgrof@kernel.org, sujiaxun@uniontech.com, feng.tang@intel.com, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] mm: memcontrol: protect the memory in cgroup from being oom killed Message-ID: References: <20221130070158.44221-1-chengkaitao@didiglobal.com> MIME-Version: 1.0 Content-Type: text/plain; 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s=arc-20220608; d=hostedemail.com; t=1669814109; a=rsa-sha256; cv=none; b=MFFPSaMFJ7IF+dwl7/tTvhysMUoYi9Py2QbxJxeMc/98Hf7/nKct/tzzis32tSAWDqxItM o+SQMPw7h2JwyIYlfcZYuoBJDhbFAQe5vfQ9wHOV+2VaQC3CsnRwvix57FNmUekEHqio58 NZm3kU+Lt/b8YXJ4h2oIPgsroQ2p1kA= X-Stat-Signature: ai8cwgbs63xoghgutqzcjdpnxyt6j1ne X-Rspamd-Queue-Id: A290AC0011 Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=CJ5yMJnr; spf=pass (imf22.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.28 as permitted sender) smtp.mailfrom=mhocko@suse.com; dmarc=pass (policy=quarantine) header.from=suse.com X-Rspamd-Server: rspam06 X-Rspam-User: X-HE-Tag: 1669814108-316795 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 30-11-22 15:01:58, chengkaitao wrote: > From: chengkaitao > > We created a new interface for memory, If there is > the OOM killer under parent memory cgroup, and the memory usage of a > child cgroup is within its effective oom.protect boundary, the cgroup's > tasks won't be OOM killed unless there is no unprotected tasks in other > children cgroups. It draws on the logic of in the > inheritance relationship. Could you be more specific about usecases? How do you tune oom.protect wrt to other tunables? How does this interact with the oom_score_adj tunining (e.g. a first hand oom victim with the score_adj 1000 sitting in a oom protected memcg)? I haven't really read through the whole patch but this struck me odd. > @@ -552,8 +552,19 @@ static int proc_oom_score(struct seq_file *m, struct pid_namespace *ns, > unsigned long totalpages = totalram_pages() + total_swap_pages; > unsigned long points = 0; > long badness; > +#ifdef CONFIG_MEMCG > + struct mem_cgroup *memcg; > > - badness = oom_badness(task, totalpages); > + rcu_read_lock(); > + memcg = mem_cgroup_from_task(task); > + if (memcg && !css_tryget(&memcg->css)) > + memcg = NULL; > + rcu_read_unlock(); > + > + update_parent_oom_protection(root_mem_cgroup, memcg); > + css_put(&memcg->css); > +#endif > + badness = oom_badness(task, totalpages, MEMCG_OOM_PROTECT); the badness means different thing depending on which memcg hierarchy subtree you look at. Scaling based on the global oom could get really misleading. -- Michal Hocko SUSE Labs