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

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Message-ID: <20180123172246.GG1771050@devbig577.frc2.facebook.com>
Date:   Tue, 23 Jan 2018 09:22:46 -0800
From:   Tejun Heo <tj@...nel.org>
To:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Petr Mladek <pmladek@...e.com>, akpm@...ux-foundation.org,
        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>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Jan Kara <jack@...e.cz>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        rostedt@...e.goodmis.org, Byungchul Park <byungchul.park@....com>,
        Pavel Machek <pavel@....cz>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 0/2] printk: Console owner and waiter logic cleanup

Hello, Sergey.

On Wed, Jan 24, 2018 at 01:01:53AM +0900, Sergey Senozhatsky wrote:
> On (01/23/18 10:41), Steven Rostedt wrote:
> [..]
> > We can have more. But if printk is causing printks, that's a major bug.
> > And work queues are not going to fix it, it will just spread out the
> > pain. Have it be 100 printks, it needs to be fixed if it is happening.
> > And having all printks just generate more printks is not helpful. Even
> > if we slow them down. They will still never end.
> 
> Dropping the messages is not the solution either. The original bug report
> report was - this "locks up my kernel". That's it. That's all people asked
> us to solve.
> 
> With WQ we don't lockup the kernel, because we flush printk_safe in
> preemptible context. And people are very much expected to fix the
> misbehaving consoles. But that should not be printk_safe problem.

I really don't care as long as it's robust enough.

Thanks.

-- 
tejun