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From: Blaisorblade <blaisorblade@yahoo.it>
To: Jeff Dike <jdike@addtoit.com>
Subject: Re: [uml-devel] [PATCH 06/10] uml: run mconsole "sysrq" in process context
Date: Thu, 22 Sep 2005 22:48:21 +0200
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Cc: user-mode-linux-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org
References: <200509211923.21861.blaisorblade@yahoo.it> <200509222120.20922.blaisorblade@yahoo.it> <20050922203743.GA11648@ccure.user-mode-linux.org>
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On Thursday 22 September 2005 22:37, Jeff Dike wrote:
> On Thu, Sep 22, 2005 at 09:20:20PM +0200, Blaisorblade wrote:
> > sysrq t is broken (and stays),

> There's a fix on the way for that.
Already found? Nice.
> This has nothing to do with interrupt 
> context anyway.

> > but additionally there are some warnings from
> > some commands (enable sleep inside spinlock checking and spinlock
> > debugging), which go to the down_read inside handle_page_fault IIRC. So
> > try to run in process context.

> Which ones?  They should be fixed.
Ok, will drop this patch and retry again to look at the messages.
> It is fairly fundamental to sysrq that it work from interrupt context.  You
> may be diagnosing a system which can't context switch any more.

Ok, I felt a bit uncertain about this, but didn't realize this very problem.

> This patch should be dropped, and the real problems fixed.
Ok, that's nice for me. I'll look into this. Possibly, the

if (in_atomic()) don't take semaphore in handle_page_fault was the right fix 
for this. I'll have a look soon.
> 				Jeff

-- 
Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!".
Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894)
http://www.user-mode-linux.org/~blaisorblade

		
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