linux-kernel - Re: [PATCH] printk: inject caller information into the body of message

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Message-ID: <197be25e-c841-bf3c-7081-61f0a9653c8c@i-love.sakura.ne.jp>
Date:   Fri, 22 Jun 2018 22:06:45 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
To:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Fengguang Wu <fengguang.wu@...el.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Petr Mladek <pmladek@...e.com>,
        syzkaller <syzkaller@...glegroups.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] printk: inject caller information into the body of
 message

On 2018/06/20 22:06, Sergey Senozhatsky wrote:
> On (06/20/18 13:32), Dmitry Vyukov wrote:
>>> So, if we could get rid of pr_cont() from the most important parts
>>> (instruction dumps, etc) then I would just vote to leave pr_cont()
>>> alone and avoid any handling of it in printk context tracking. Simply
>>> because we wouldn't care about pr_cont(). This also could simplify
>>> Tetsuo's patch significantly.
>>
>> Sounds good to me.
> 
> Awesome. If you and Fengguang can combine forces and lead the
> whole thing towards "we couldn't care of pr_cont() less", it
> would be really huuuuuge. Go for it!

Can't we have seq_printf()-like one which flushes automatically upon seeing '\n'
or buffer full? Printing memory information is using a lot of pr_cont(), even in
function names (e.g. http://lkml.kernel.org/r/20180622083949.GR10465@dhcp22.suse.cz ).
Since OOM killer code is serialized by oom_lock, we can use static buffer for
OOM killer messages.