linux-kernel - Re: a different perf tracepoint bug

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Message-ID: <alpine.DEB.2.10.1311061656250.27317@vincent-weaver-1.um.maine.edu>
Date:	Wed, 6 Nov 2013 17:00:37 -0500 (EST)
From:	Vince Weaver <vincent.weaver@...ne.edu>
To:	Steven Rostedt <rostedt@...dmis.org>
cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Jiri Olsa <jolsa@...hat.com>, Dave Jones <davej@...hat.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Kees Cook <keescook@...gle.com>
Subject: Re: a different perf tracepoint bug

On Wed, 6 Nov 2013, Steven Rostedt wrote:

> > [11559.476002]  <<EOE>>  <IRQ>  [<ffffffff8104acaa>] ? __send_signal+0xd8/0x26f
> 
> Can you find the exact location of __send_signal()?

I'm not sure what you mean, but:

addr2line -e ./vmlinux ffffffff8104acaa
linux-kernel/linux-3.12/kernel/signal.c:1095

which is

        q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
                override_rlimit);
-->     if (q) {
                list_add_tail(&q->list, &pending->list);
                switch ((unsigned long) info) {
                case (unsigned long) SEND_SIG_NOINFO:
...


though this might just be a case where tracepoints are happening too 
quickly and the kernel gets stuck and can't keep up.  Previously I was
using a hacked kernel that made the watchdog continually print rather than 
just warn once, the better to see if any progress was being made.

Vince
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