linux-kernel - Re: [RFC PATCH] memcg, oom: throttle dump_header for memcg ooms without eligible tasks

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Date:   Tue, 16 Oct 2018 13:17:07 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Cc:     Johannes Weiner <hannes@...xchg.org>, linux-mm@...ck.org,
        syzkaller-bugs@...glegroups.com, guro@...com,
        kirill.shutemov@...ux.intel.com, linux-kernel@...r.kernel.org,
        rientjes@...gle.com, yang.s@...baba-inc.com,
        Andrew Morton <akpm@...ux-foundation.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [RFC PATCH] memcg, oom: throttle dump_header for memcg ooms
 without eligible tasks

On Tue 16-10-18 20:05:47, Tetsuo Handa wrote:
> On 2018/10/16 18:20, Michal Hocko wrote:
> >> Anyway, I'm OK if we apply _BOTH_ your patch and my patch. Or I'm OK with simplified
> >> one shown below (because you don't like per memcg limit).
> > 
> > My patch is adding a rate-limit! I really fail to see why we need yet
> > another one on top of it. This is just ridiculous. I can see reasons to
> > tune that rate limit but adding 2 different mechanisms is just wrong.
> > 
> > If your NAK to unify the ratelimit for dump_header for all paths
> > still holds then I do not care too much to push it forward. But I find
> > thiis way of the review feedback counter productive.
> > 
> 
> Your patch is _NOT_ adding a rate-limit for
> 
>   "%s invoked oom-killer: gfp_mask=%#x(%pGg), nodemask=%*pbl, order=%d, oom_score_adj=%hd\n"
>   "Out of memory and no killable processes...\n"
> 
> lines!

And I've said I do not have objections to have an _incremental_ patch to
move the ratelimit up with a clear cost/benefit evaluation.
-- 
Michal Hocko
SUSE Labs