linux-kernel - Re: BUG: sleeping function called from invalid context at kernel/mutex.c

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Message-Id: <201104060643.38301.rjw@sisk.pl>
Date:	Wed, 6 Apr 2011 06:43:38 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Xiaotian Feng <dfeng@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>,
	Venkatesh Pallipadi <venki@...gle.com>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: BUG: sleeping function called from invalid context at kernel/mutex.c

On Tuesday, April 05, 2011, Peter Zijlstra wrote:
> On Sat, 2011-04-02 at 21:12 +0200, Thomas Gleixner wrote:
> > 
> > And it is safe enough for the resume case as well, it simply cannot go
> > to sleep because nothing else can hold that mutex in the early resume
> > code. We take the mutex during early boot as well, but there the might
> > sleep checks are disabled. And we should do the very same thing in the
> > early resume code as well. Rafael, PeterZ ??? 
> 
> the $subject text sound like it triggered might_sleep(), and that had a
> system_state != SYSTEM_RUNNING bail condition, but then, I've no clue
> what resume looks like.

Early resume looks pretty much like the system startup, e.g. everything
called from syscore_ops should not be sleepable (although mutexes shouldn't
trigger, because that code is effectively single-threaded, unless somebody
holds the mutex in question when that code is being executed, but that would
deadlock anyway).

Thanks,
Rafael
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