linux-kernel - Re: frequent softlockups with 3.10rc6.

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Message-ID: <20130626052352.GB31416@redhat.com>
Date:	Wed, 26 Jun 2013 01:23:52 -0400
From:	Dave Jones <davej@...hat.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Oleg Nesterov <oleg@...hat.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Andrey Vagin <avagin@...nvz.org>
Subject: Re: frequent softlockups with 3.10rc6.

On Tue, Jun 25, 2013 at 12:23:34PM -0400, Steven Rostedt wrote:

 > Now, what we can try to do as well, is to add a trigger to disable
 > tracing, which should (I need to check the code) stop tracing on printk.
 > To do so:
 > 
 > # echo printk:traceoff > /sys/kernel/debug/tracing/set_ftrace_filter
 > 
 > This will add a trigger to the printk function that when called, will
 > disable tracing. If it is hit before you get your trace, you can just
 > re-enable tracing with:
 > 
 > # echo 1 > /sys/kernel/debug/tracing/tracing_on
 > 
 > Hmm, no it needs a fix to make this work. I applied a patch below that
 > should do this correctly (and will put this into my 3.11 queue).
 > 
 > If you run the test again with this change and with the above filter, it
 > should stop the trace before overwriting the first dump, as it should
 > ignore the printk output.

I think something isn't right with this patch.
After 10 hours, I hit the bug again, but...

(01:21:28:root@...ary:tracing)# cat trace
# tracer: preemptirqsoff
#
(01:21:30:root@...ary:tracing)# 

	Dave

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