From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f200.google.com (mail-pf1-f200.google.com [209.85.210.200]) by kanga.kvack.org (Postfix) with ESMTP id 188186B0003 for ; Mon, 6 Aug 2018 14:40:04 -0400 (EDT) Received: by mail-pf1-f200.google.com with SMTP id e15-v6so9068833pfi.5 for ; Mon, 06 Aug 2018 11:40:04 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id z137-v6si11755666pgz.144.2018.08.06.11.40.02 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 06 Aug 2018 11:40:02 -0700 (PDT) Date: Mon, 6 Aug 2018 20:39:54 +0200 From: Michal Hocko Subject: Re: WARNING in try_charge Message-ID: <20180806183954.GF10003@dhcp22.suse.cz> References: <0000000000006350880572c61e62@google.com> <20180806174410.GB10003@dhcp22.suse.cz> <20180806175627.GC10003@dhcp22.suse.cz> <20180806181339.GD10003@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180806181339.GD10003@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: syzbot Cc: cgroups@vger.kernel.org, dvyukov@google.com, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, penguin-kernel@I-love.SAKURA.ne.jp, syzkaller-bugs@googlegroups.com, vdavydov.dev@gmail.com On Mon 06-08-18 20:13:39, Michal Hocko wrote: > I simply do not see how this is possible. Let's try with the following > extended debugging patch. > > #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git 116b181bb646afedd770985de20a68721bdb2648 > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 4603ad75c9a9..e2dfdf4361ba 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -1388,6 +1388,8 @@ static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, > bool ret; > > mutex_lock(&oom_lock); > + pr_info("task=%s pid=%d invoked memcg oom killer. oom_victim=%d\n", > + current->comm, current->pid, tsk_is_oom_victim(current)); > ret = out_of_memory(&oc); > mutex_unlock(&oom_lock); > return ret; > @@ -2108,6 +2110,9 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, > > if (mem_cgroup_is_root(memcg)) > return 0; > + if (tsk_is_oom_victim(current)) > + pr_info("task=%s pid=%d charge for nr_pages=%d\n", > + current->comm, current->pid, nr_pages); > retry: > if (consume_stock(memcg, nr_pages)) > return 0; > @@ -2137,8 +2142,11 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, > */ > if (unlikely(tsk_is_oom_victim(current) || > fatal_signal_pending(current) || > - current->flags & PF_EXITING)) > + current->flags & PF_EXITING)) { > + pr_info("task=%s pid=%d charge bypass\n", > + current->comm, current->pid); > goto force; > + } > > /* > * Prevent unbounded recursion when reclaim operations need to > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index 104ef4a01a55..7d9adcde8cf6 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -692,6 +692,8 @@ static void mark_oom_victim(struct task_struct *tsk) > __thaw_task(tsk); > atomic_inc(&oom_victims); > trace_mark_victim(tsk->pid); > + pr_info("task=%s pid=%d is oom victim now\n", > + current->comm, current->pid); > } Ble this should be s@current@tsk@g. But it didn't really help. I will have to think about this more. -- Michal Hocko SUSE Labs