From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BD081ECDE43 for ; Thu, 18 Oct 2018 11:24:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8D18021476 for ; Thu, 18 Oct 2018 11:24:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8D18021476 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727649AbeJRTYf (ORCPT ); Thu, 18 Oct 2018 15:24:35 -0400 Received: from mx2.suse.de ([195.135.220.15]:43906 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727365AbeJRTYf (ORCPT ); Thu, 18 Oct 2018 15:24:35 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 94BBDAE10; Thu, 18 Oct 2018 11:23:59 +0000 (UTC) Date: Thu, 18 Oct 2018 13:23:58 +0200 From: Michal Hocko To: Tetsuo Handa Cc: Sergey Senozhatsky , Johannes Weiner , linux-mm@kvack.org, syzkaller-bugs@googlegroups.com, guro@fb.com, kirill.shutemov@linux.intel.com, linux-kernel@vger.kernel.org, rientjes@google.com, yang.s@alibaba-inc.com, Andrew Morton , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , syzbot Subject: Re: [PATCH v3] mm: memcontrol: Don't flood OOM messages with no eligible task. Message-ID: <20181018112358.GB18839@dhcp22.suse.cz> References: <20181017102821.GM18839@dhcp22.suse.cz> <20181017111724.GA459@jagdpanzerIV> <201810180246.w9I2koi3011358@www262.sakura.ne.jp> <20181018065519.GV18839@dhcp22.suse.cz> <6bbb0449-1f22-4d05-9e2a-636965b7dbc6@i-love.sakura.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6bbb0449-1f22-4d05-9e2a-636965b7dbc6@i-love.sakura.ne.jp> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 18-10-18 19:37:18, Tetsuo Handa wrote: > On 2018/10/18 15:55, Michal Hocko wrote: > > On Thu 18-10-18 11:46:50, Tetsuo Handa wrote: > >> This is essentially a ratelimit approach, roughly equivalent with: > >> > >> static DEFINE_RATELIMIT_STATE(oom_no_victim_rs, 60 * HZ, 1); > >> oom_no_victim_rs.flags |= RATELIMIT_MSG_ON_RELEASE; > >> > >> if (__ratelimit(&oom_no_victim_rs)) { > >> dump_header(oc, NULL); > >> pr_warn("Out of memory and no killable processes...\n"); > >> oom_no_victim_rs.begin = jiffies; > >> } > > > > Then there is no reason to reinvent the wheel. So use the standard > > ratelimit approach. Or put it in other words, this place is no special > > to any other that needs some sort of printk throttling. We surely do not > > want an ad-hoc solutions all over the kernel. > > netdev_wait_allrefs() in net/core/dev.c is doing the same thing. Since > out_of_memory() is serialized by oom_lock mutex, there is no need to use > "struct ratelimit_state"->lock field. Plain "unsigned long" is enough. That code probably predates generalized ratelimit api. > > And once you realize that the ratelimit api is the proper one (put aside > > any potential improvements in the implementation of this api) then you > > quickly learn that we already do throttle oom reports and it would be > > nice to unify that and ... we are back to a naked patch. So please stop > > being stuborn and try to cooperate finally. > > I don't think that ratelimit API is the proper one, for I am touching > "struct ratelimit_state"->begin field which is not exported by ratelimit API. > But if you insist on ratelimit API version, I can tolerate with below one. I just give up. I do not really see why you always have to make the code more complex than necessary and squash different things together. This is a complete kernel code development antipattern. I am not goging to reply to this thread more but let me note that this is beyond fun in any aspect I can think off (and yeah I have considered dark sense of humor as well). > > mm/oom_kill.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index f10aa53..7c6118e 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -1106,6 +1106,12 @@ bool out_of_memory(struct oom_control *oc) > select_bad_process(oc); > /* Found nothing?!?! */ > if (!oc->chosen) { > + static DEFINE_RATELIMIT_STATE(no_eligible_rs, 60 * HZ, 1); > + > + ratelimit_set_flags(&no_eligible_rs, RATELIMIT_MSG_ON_RELEASE); > + if ((is_sysrq_oom(oc) || is_memcg_oom(oc)) && > + !__ratelimit(&no_eligible_rs)) > + return false; > dump_header(oc, NULL); > pr_warn("Out of memory and no killable processes...\n"); > /* > @@ -1115,6 +1121,7 @@ bool out_of_memory(struct oom_control *oc) > */ > if (!is_sysrq_oom(oc) && !is_memcg_oom(oc)) > panic("System is deadlocked on memory\n"); > + no_eligible_rs.begin = jiffies; > } > if (oc->chosen && oc->chosen != (void *)-1UL) > oom_kill_process(oc, !is_memcg_oom(oc) ? "Out of memory" : > -- > 1.8.3.1 -- Michal Hocko SUSE Labs