From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it1-f199.google.com (mail-it1-f199.google.com [209.85.166.199]) by kanga.kvack.org (Postfix) with ESMTP id B9BCF6B0008 for ; Thu, 18 Oct 2018 06:37:52 -0400 (EDT) Received: by mail-it1-f199.google.com with SMTP id e197-v6so5162653ita.9 for ; Thu, 18 Oct 2018 03:37:52 -0700 (PDT) Received: from www262.sakura.ne.jp (www262.sakura.ne.jp. [202.181.97.72]) by mx.google.com with ESMTPS id e27-v6si261086jal.38.2018.10.18.03.37.51 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 18 Oct 2018 03:37:51 -0700 (PDT) Subject: Re: [PATCH v3] mm: memcontrol: Don't flood OOM messages with no eligible task. References: <20181017102821.GM18839@dhcp22.suse.cz> <20181017111724.GA459@jagdpanzerIV> <201810180246.w9I2koi3011358@www262.sakura.ne.jp> <20181018065519.GV18839@dhcp22.suse.cz> From: Tetsuo Handa Message-ID: <6bbb0449-1f22-4d05-9e2a-636965b7dbc6@i-love.sakura.ne.jp> Date: Thu, 18 Oct 2018 19:37:18 +0900 MIME-Version: 1.0 In-Reply-To: <20181018065519.GV18839@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko 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 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. > > 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. 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