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[202.181.97.72]) by mx.google.com with ESMTPS id f14si3757863otl.238.2019.06.15.09.49.09 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 15 Jun 2019 09:49:10 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of penguin-kernel@i-love.sakura.ne.jp designates 202.181.97.72 as permitted sender) client-ip=202.181.97.72; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of penguin-kernel@i-love.sakura.ne.jp designates 202.181.97.72 as permitted sender) smtp.mailfrom=penguin-kernel@i-love.sakura.ne.jp Received: from fsav106.sakura.ne.jp (fsav106.sakura.ne.jp [27.133.134.233]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id x5FGmXSn070660; Sun, 16 Jun 2019 01:48:33 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav106.sakura.ne.jp (F-Secure/fsigk_smtp/530/fsav106.sakura.ne.jp); Sun, 16 Jun 2019 01:48:33 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/530/fsav106.sakura.ne.jp) Received: from [192.168.1.8] (softbank126012062002.bbtec.net [126.12.62.2]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id x5FGmXuT070654 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NO); Sun, 16 Jun 2019 01:48:33 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: Re: general protection fault in oom_unkillable_task To: Shakeel Butt , Michal Hocko Cc: syzbot , Andrew Morton , "Eric W. Biederman" , Roman Gushchin , Johannes Weiner , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , LKML , Linux MM , syzkaller-bugs , yuzhoujian@didichuxing.com References: <0000000000004143a5058b526503@google.com> <20190615134955.GA28441@dhcp22.suse.cz> From: Tetsuo Handa Message-ID: <5bb1fe5d-f0e1-678b-4f64-82c8d5d81f61@i-love.sakura.ne.jp> Date: Sun, 16 Jun 2019 01:48:31 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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 2019/06/16 1:11, Shakeel Butt wrote: > On Sat, Jun 15, 2019 at 6:50 AM Michal Hocko wrote: >> diff --git a/mm/oom_kill.c b/mm/oom_kill.c >> index 5a58778c91d4..43eb479a5dc7 100644 >> --- a/mm/oom_kill.c >> +++ b/mm/oom_kill.c >> @@ -161,8 +161,8 @@ static bool oom_unkillable_task(struct task_struct *p, >> return true; >> >> /* When mem_cgroup_out_of_memory() and p is not member of the group */ >> - if (memcg && !task_in_mem_cgroup(p, memcg)) >> - return true; >> + if (memcg) >> + return false; > > This will break the dump_tasks() usage of oom_unkillable_task(). We > can change dump_tasks() to traverse processes like > mem_cgroup_scan_tasks() for memcg OOMs. While dump_tasks() traverses only each thread group, mem_cgroup_scan_tasks() traverses each thread. To avoid printk()ing all threads in a thread group, moving that check to if (memcg && !task_in_mem_cgroup(p, memcg)) continue; in dump_tasks() is better? > >> >> /* p may not have freeable memory in nodemask */ >> if (!has_intersects_mems_allowed(p, nodemask))