Date: Tue, 16 Jan 2018 11:44:56 -0800
From: Tejun Heo <tj@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Petr Mladek <pmladek@suse.com>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        akpm@linux-foundation.org, linux-mm@kvack.org,
        Cong Wang <xiyou.wangcong@gmail.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Mel Gorman <mgorman@suse.de>, Michal Hocko <mhocko@kernel.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Peter Zijlstra <peterz@infradead.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Jan Kara <jack@suse.cz>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
        rostedt@home.goodmis.org, Byungchul Park <byungchul.park@lge.com>,
        Pavel Machek <pavel@ucw.cz>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 0/2] printk: Console owner and waiter logic cleanup
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Hello, Steven.

On Thu, Jan 11, 2018 at 09:55:47PM -0500, Steven Rostedt wrote:
> All I did was start off a work queue on each CPU, and each CPU does one
> printk() followed by a millisecond sleep. No 10,000 printks, nothing
> in an interrupt handler. Preemption is disabled while the printk
> happens, but that's normal.
> 
> This is much closer to an OOM happening all over the system, where OOMs
> stack dumps are occurring on different CPUS.

OOMs can't happen all over the system.  It can only happen on a single
CPU at a time.  If you're printing from multiple CPUs, your solution
would work great.  That is the situation your patches are designed to
address to begin with.  That isn't the problem that I reported tho.  I
understand that your solution works for that class of problems and
that is great.  I really wish that it could address the other class of
problems too tho, and it doesn't seem like it would be that difficult
to cover both cases, right?

Thanks.

-- 
tejun