linux-kernel - Re: ratelimit API: was: [RFC PATCH] printk: Introduce "store now but print later" prefix.

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Message-ID: <20190321084940.GL8696@dhcp22.suse.cz>
Date:   Thu, 21 Mar 2019 09:49:40 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Cc:     Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        John Ogness <john.ogness@...utronix.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-kernel@...r.kernel.org
Subject: Re: ratelimit API: was: [RFC PATCH] printk: Introduce "store now but
 print later" prefix.

On Thu 21-03-19 17:13:54, Tetsuo Handa wrote:
> On 2019/03/21 0:25, Petr Mladek wrote:
> >> This requires serialization among threads using "rs". I already
> >> proposed ratelimit_reset() for memcg's OOM problem at
> >> https://lkml.kernel.org/r/201810180246.w9I2koi3011358@www262.sakura.ne.jp
> >> but it was not accepted.
> > 
> > IMHO, the main problem was that the patch tried to work around
> > the ratelimit API weakness by a custom code.
> > 
> > I believe that using an improved/extended ratelimit API with
> > a sane semantic would be more acceptable.
> > 
> 
> Michal, are you OK to use ratelimit_reset() in out_of_memory()
> if ratelimit_reset() is accepted?

I do not know what ratelimit_reset is but if that is a new API for
a more reasonable ratelimiting then sure, I do not have any objections.
I have been objecting to one-off hacks to workaround problems of the
existing api.

-- 
Michal Hocko
SUSE Labs