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From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>, Peter Hurley <peter@hurleysoftware.com>,
        Davidlohr Bueso <dave@stgolabs.net>,
        Peter Zijlstra <peterz@infradead.org>,
        Bruno =?ISO-8859-1?Q?Pr=E9mont?= <bonbons@linux-vserver.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ilya Dryomov <ilya.dryomov@inktank.com>,
        Mike Galbraith <umgwanakikbuti@gmail.com>,
        Oleg Nesterov <oleg@redhat.com>
Subject: Re: Linux 3.19-rc5
Date: Fri, 30 Jan 2015 03:06:11 +0100
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On Thursday, January 29, 2015 05:25:07 PM Linus Torvalds wrote:
> On Thu, Jan 29, 2015 at 5:12 PM, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > The WARN() was already changed to a WARN_ONCE().
> 
> Oh, but I notice that the "__set_current_state(TASK_RUNNING) ends up
> always happening.
> 
> So I think the right fix is to:
> 
>  - warn once like we do
> 
>  - but *not* do that __set_current_state() which was always total crap anyway
> 
> Why do I say "total crap"? Because of two independent issues:
> 
>  (a) it actually changes behavior for a debug vs non-debug kernel,
> which is a really bad idea to begin with
> 
>  (b) it's really wrong. The whole "nested sleep" case was never a
> major bug to begin with, just a possible inefficiency where constant
> nested sleeps would possibly make the outer sleep not sleep. But that
> "could possibly make" case was the unlikely case, and the debug patch
> made it happen *all* the time by explicitly setting things running.
> 
> So I think the proper patch is the attached.

I applied the patch and compiled the kernel with CONFIG_DEBUG_ATOMIC_SLEEP
set again.  The warning is back, so the DEBUG_ATOMIC_SLEEP thing appears to
be working (and I don't really care about the freaking warning anyway), but the
pccardd load issue is gone, so the patch fixes the problem for me.  Thanks!

Rafael