linux-kernel - Re: [PATCH v5 0/2] printk: Console owner and waiter logic cleanup

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Message-ID: <20180111073618.GA477@jagdpanzerIV>
Date:   Thu, 11 Jan 2018 16:36:18 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc:     Tejun Heo <tj@...nel.org>, Petr Mladek <pmladek@...e.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        linux-mm <linux-mm@...ck.org>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Mel Gorman <mgorman@...e.de>, Michal Hocko <mhocko@...nel.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Peter Zijlstra <peterz@...radead.org>, Jan Kara <jack@...e.cz>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        rostedt@...e.goodmis.org, Byungchul Park <byungchul.park@....com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Pavel Machek <pavel@....cz>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 0/2] printk: Console owner and waiter logic cleanup

Hi Mathieu,

On (01/10/18 18:40), Mathieu Desnoyers wrote:
[..]
> 
> There appears to be two problems at hand. One is making sure a console
> buffer owner only flushes a bounded amount of data.

which, realistically, has quite little to do with the "and thus it
fixes the lockups". logbuf size is mutable, the number of consoles we
need to sequentially push the data to is mutable, the watchdog threshold
is mutable... if combination of first two mutable things produces the
result which makes the check based on the third mutable thing happy,
then it's just an accident. my 5 cents.

	-ss