linux-kernel - Re: [PATCH v3] mm: memcontrol: Don't flood OOM messages with no eligible task.

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Message-Id: <201810180526.w9I5QvVn032670@www262.sakura.ne.jp>
Date:   Thu, 18 Oct 2018 14:26:57 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Michal Hocko <mhocko@...nel.org>,
        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>,
        Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        syzbot <syzbot+77e6b28a7a7106ad0def@...kaller.appspotmail.com>
Subject: Re: [PATCH v3] mm: memcontrol: Don't flood OOM messages with no eligible
 task.

Sergey Senozhatsky wrote:
> To my personal taste, "baud rate of registered and enabled consoles"
> approach is drastically more relevant than hard coded 10 * HZ or
> 60 * HZ magic numbers... But not in the form of that "min baud rate"
> brain fart, which I have posted.

I'm saying that my 60 * HZ is "duration which the OOM killer keeps refraining
 from calling printk()". Such period is required for allowing console users
to do their operations without being disturbed by the OOM killer.

Even if you succeeded to calculate average speed of the OOM killer messages
being flushed to consoles, printing the OOM killer messages with that speed
will keep the console users unable to do their operations.

Please do not print the OOM killer messages when the OOM killer cannot make
progress... It just disturbs console users.