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Date:   Wed, 4 Sep 2019 16:43:12 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To:     Michal Hocko <mhocko@kernel.org>
Cc:     Qian Cai <cai@lca.pw>, Eric Dumazet <eric.dumazet@gmail.com>,
        davem@davemloft.net, netdev@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Petr Mladek <pmladek@suse.com>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH] net/skbuff: silence warnings under memory pressure
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On (09/04/19 16:19), Sergey Senozhatsky wrote:
> Hmm. I need to look at this more... wake_up_klogd() queues work only once
> on particular CPU: irq_work_queue(this_cpu_ptr(&wake_up_klogd_work));
> 
> bool irq_work_queue()
> {
> 	/* Only queue if not already pending */
> 	if (!irq_work_claim(work))
> 		return false;
> 
> 	 __irq_work_queue_local(work);
> }

Plus one more check - waitqueue_active(&log_wait). printk() adds
pending irq_work only if there is a user-space process sleeping on
log_wait and irq_work is not already scheduled. If the syslog is
active or there is noone to wakeup then we don't queue irq_work.

	-ss