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Date:   Thu, 21 Nov 2019 10:05:27 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To:     Petr Mladek <pmladek@suse.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Qian Cai <cai@lca.pw>, Steven Rostedt <rostedt@goodmis.org>,
        Michal Hocko <mhocko@kernel.org>,
        Eric Dumazet <eric.dumazet@gmail.com>, davem@davemloft.net,
        netdev@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net/skbuff: silence warnings under memory pressure
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On (19/11/20 17:13), Petr Mladek wrote:
[..]
> It is the first time that I hear about problem caused by the
> irq_work(). But we deal with deadlocks caused by wake_up() for years.
> It would be like replacing a lightly dripping tap with a heavily
> dripping one.
> 
> I see reports with WARN() from scheduler code from time to time.
> I would get reports about silent death instead.

Just curious, how many of those WARN() come under rq lock or pi_lock?
// this is real question

> RT guys are going to make printk() fully lockless. It would be
> really great achievement. irq_work is lockless. While wake_up()
> is not.
>
> There must be a better way how to break the infinite loop caused
> by the irq_work.

A lockless wake_up() would do :)

	-ss