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From: Peter Zijlstra <peterz@infradead.org>
To: Vince Weaver <vincent.weaver@maine.edu>
Cc: Sasha Levin <sasha.levin@oracle.com>,
	linux-kernel@vger.kernel.org, Paul Mackerras <paulus@samba.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: Re: perf: perf_fuzzer triggers instant reboot
Date: Wed, 10 Sep 2014 16:33:06 +0200	[thread overview]
Message-ID: <20140910143306.GD4783@worktop.ger.corp.intel.com> (raw)
In-Reply-To: <alpine.DEB.2.11.1409101027250.8981@vincent-weaver-1.umelst.maine.edu>

On Wed, Sep 10, 2014 at 10:30:31AM -0400, Vince Weaver wrote:
> On Wed, 10 Sep 2014, Sasha Levin wrote:
> 
> > On 09/10/2014 09:18 AM, Vince Weaver wrote:
> > > that's what got me looking at things again, the trinity reports.  Though I 
> > > think those involve CPU hotplugging which my fuzzer shouldn't trigger.
> > > 
> > > I do think this is the same memory corruption/reboot bug that I reported 
> > > back in February (the thread is "perf_fuzzer compiled for x32 causes 
> > > reboot" but I wasn't able to isolate the problem then either.
> > > 
> > > Somehow something is stomping over memory with a forking workload (likely 
> > > an improper free with RCU like we've seen before) but the fact that it 
> > > causes a reboot immediately makes it *really* hard to debug this.
> > 
> > Could this be http://permalink.gmane.org/gmane.linux.kernel/1779436 which
> > I saw couple days ago?
> 
> It could be.
> 
> I have about 10 open bugs with similar symptoms found with my perf_fuzzer 
> here (and a few more that are possibly the same memory corruption bug that 
> "fixes" went into the kernel but it's unclear if it actually fixed things
> or just altered the locking enough to make it harder to hit).
> 
> 	http://web.eece.maine.edu/~vweaver/projects/perf_events/fuzzer/bugs_found.html
> 
> I've been trying for months now to make progress on these but this type of 
> bug is really hard to debug.

Did we actually fix some at least? I had the idea we did get a few
sorted. But yes, this is tedious and hard going :/

  reply	other threads:[~2014-09-10 14:33 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-08 17:47 Vince Weaver
2014-09-08 18:51 ` Peter Zijlstra
2014-09-08 19:08   ` Vince Weaver
2014-09-09 16:06   ` Vince Weaver
2014-09-09 17:20     ` Vince Weaver
2014-09-09 17:53       ` Vince Weaver
2014-09-10  8:31         ` Peter Zijlstra
2014-09-10 13:18           ` Vince Weaver
2014-09-10 13:28             ` Peter Zijlstra
2014-09-10 14:01             ` Sasha Levin
2014-09-10 14:30               ` Vince Weaver
2014-09-10 14:33                 ` Peter Zijlstra [this message]
2014-09-11 13:27                   ` Vince Weaver
2014-09-25  4:59                     ` Vince Weaver
2014-09-25 16:38                       ` Cong Wang
2014-09-28  4:09                         ` Sasha Levin
2014-09-29 11:11                           ` Peter Zijlstra
2014-09-29 17:01                             ` Sasha Levin
2014-09-30  8:54                               ` Peter Zijlstra
2014-09-30 17:23                           ` Peter Zijlstra
2014-10-01 11:16                             ` Sasha Levin
2014-10-02 15:06                               ` Vince Weaver
2014-10-02 16:06                                 ` Vince Weaver
2014-10-03  5:27                             ` [tip:perf/urgent] perf: Fix unclone_ctx() vs. locking tip-bot for Peter Zijlstra
2014-09-29  5:21                         ` perf: perf_fuzzer triggers instant reboot Vince Weaver
2014-09-30 17:58                           ` Cong Wang

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