linux-kernel - Re: [Query] Preemption (hogging) of the work handler

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Message-ID: <20160712093805.GA498@swordfish>
Date:	Tue, 12 Jul 2016 18:38:05 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	Jan Kara <jack@...e.cz>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Tejun Heo <tj@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	vlevenetz@...sol.com, vaibhav.hiremath@...aro.org,
	alex.elder@...aro.org, johan@...nel.org, akpm@...ux-foundation.org,
	rostedt@...dmis.org,
	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Subject: Re: [Query] Preemption (hogging) of the work handler

Hello,

On (07/11/16 15:35), Viresh Kumar wrote:
[..]
> Sometimes, the platform doesn't come back after suspend. I have tried
> enabling no-console-suspend and the last line it prints is:
> 
>         Disabling non-boot CPUs
> 
> And nothing after that at all. We have to forcefully reboot the phone
> after that. Moving the prints to they synchronous way (using
> echo 1 > /sys/module/printk/parameters/synchronous), fixes that issue.

hm... I'll take a look.

> So, the asynchronous printing have a issue that only we are hitting.
> It looks like that all the CPUs are gone except CPU0 and that CPU is
> hogged by the printk thread to print stuff as well as to suspend the
> system, and something eventually gets wrong.

	-ss