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[202.181.97.72]) by mx.google.com with ESMTPS id v23si4669942oif.133.2019.06.17.02.57.39 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 17 Jun 2019 02:57:40 -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 fsav401.sakura.ne.jp (fsav401.sakura.ne.jp [133.242.250.100]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id x5H9upm3052739; Mon, 17 Jun 2019 18:56:51 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav401.sakura.ne.jp (F-Secure/fsigk_smtp/530/fsav401.sakura.ne.jp); Mon, 17 Jun 2019 18:56:51 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/530/fsav401.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 x5H9uksP052600 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NO); Mon, 17 Jun 2019 18:56:50 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: Re: general protection fault in oom_unkillable_task To: Michal Hocko , Shakeel Butt 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> <20190617063319.GB30420@dhcp22.suse.cz> From: Tetsuo Handa Message-ID: <268214f9-18ef-b63e-2d4f-c344a7dd5e72@i-love.sakura.ne.jp> Date: Mon, 17 Jun 2019 18:56:47 +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: <20190617063319.GB30420@dhcp22.suse.cz> 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 2019/06/17 15:33, Michal Hocko wrote: > On Sat 15-06-19 09:11:37, 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. > > Right you are. Doing a similar trick to the oom victim selection is > indeed better. We should really strive to not doing a global process > iteration when we can do a targeted scan. Care to send a patch? I posted a patch that (as a side effect) avoids oom_unkillable_task() from dump_tasks() at https://lore.kernel.org/linux-mm/1558519686-16057-2-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp/ . What do you think?