Re: [nacked] mm-oom-avoid-printk-iteration-under-rcu.patch removed from -mm tree

[Michal Hocko <mhocko@suse.com>]

On Thu 23-04-20 22:28:00, Tetsuo Handa wrote:
> On 2020/04/23 20:07, Michal Hocko wrote:
> > The existing loglevels we use are not really carved in stone and we can
> > prioritize some more than others. dump_tasks is KERN_INFO already and
> > this is quite a low priority so you shouldn't really miss much when
> > omitting it. But I wouldn't mind making it KERN_DEBUG.
> 
> Do you mean
> 
> -       pr_info("[%7d] %5d %5d %8lu %8lu %8ld %8lu         %5hd %s\n",
> +       pr_debug("[%7d] %5d %5d %8lu %8lu %8ld %8lu         %5hd %s\n",
> 
> in order to suppress printing to consoles?

Not with the primary intention. But reducing the log level might allow
to filter it more easily because KERN_DEBUG should really be something
that can be dropped on the floor. I am not aware of heavy KERN_INFO
users that would matter so the current log level makes sense to me but
maybe there are some and that's why I've mentioned I wouldn't be
opposed.
 
[...]

> Last year I proposed
> https://lkml.kernel.org/r/1550896930-12324-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
> and Sergey Senozhatsky commented
> 
>   "This is a bit of a strange issue, to be honest. If OOM prints too
>    many messages then we might want to do some work on the OOM side."
> 
> . I was thinking that printing to consoles is a requirement for oom_dump_tasks .
> 
> If we can agree with not printing dump_tasks() output to consoles, a trivial
> patch shown below will solve the problem. Those who cannot run syslog daemon
> in userspace might disagree, but this will be the simplest answer.

Talk to printk people about this.
-- 
Michal Hocko
SUSE Labs