From: Vince Weaver <vincent.weaver@maine.edu>
To: Stephane Eranian <eranian@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>
Subject: Re: perf: perf_fuzzer lockup in perf_cgroup_attach
Date: Thu, 15 Sep 2016 08:47:25 -0400 (EDT) [thread overview]
Message-ID: <alpine.DEB.2.20.1609150843030.13216@macbook-air> (raw)
In-Reply-To: <CABPqkBQZTFuMKYX62PXjdHtZRKxKkj=emQA3SepAidLj6tAWVg@mail.gmail.com>
On Wed, 14 Sep 2016, Stephane Eranian wrote:
> I would think there is a way to disable KASLR for this kind of testing!
yes, it's just I hadn't realized I had it enabled until I couldn't figure
out why addr2line wasn't working.
> Which of your fuzzer scripts are you using? fast_repro99.sh?
yes. I should probably give that script a more meaningful name, but by
now I think it's too late for that.
I also am running with paranoid set to "0"
>
> > The best I can tell things are getting wedged somehow in
> > perf_cgroup_switch() while interrupts are disabled. Interrupts are never
> > getting re-enabled, causing the RCU and NMI watchdogs to trigger (and more
> > alarming things like the SATA bus resetting).
> >
> How do you get to perf_cgroup_switch() from the traces you provide below?
It was my best guess after trying to trace through the code. It could
in theory be anywhere but it definitely seems like it is happening after
perf_cgroup_attach at some point when interrupts are disabled (possibly
ftrace too?)
It's difficult because some code gets inlined and then it's jumping to a
function pointer. And then mid-debug the system finally had enough and
started making threads hang forever while I was getting close.
I've rebooted the machine I'll see if I can replicate.
Vince
next prev parent reply other threads:[~2016-09-15 12:48 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-15 2:43 Vince Weaver
2016-09-15 5:35 ` Stephane Eranian
2016-09-15 7:24 ` Peter Zijlstra
2016-09-15 12:10 ` Josh Poimboeuf
2016-09-16 14:48 ` [PATCH] scripts: add script for translating stack dump function offsets Josh Poimboeuf
2016-09-16 18:12 ` Linus Torvalds
2016-09-16 19:17 ` Josh Poimboeuf
2016-09-16 19:26 ` Linus Torvalds
2016-09-16 21:26 ` [PATCH v2] " Josh Poimboeuf
2016-09-17 0:09 ` Linus Torvalds
2016-09-17 0:42 ` Josh Poimboeuf
2016-09-17 1:59 ` Linus Torvalds
2016-09-17 2:31 ` Linus Torvalds
2016-09-17 18:45 ` Josh Poimboeuf
2016-09-19 15:52 ` [PATCH v3] scripts: add script for translating stack dump function Josh Poimboeuf
2016-09-19 18:56 ` Linus Torvalds
2016-09-19 19:15 ` Linus Torvalds
2016-09-19 19:28 ` Josh Poimboeuf
2016-09-19 20:00 ` Rabin Vincent
2016-09-19 20:24 ` Linus Torvalds
2016-09-19 20:56 ` Josh Poimboeuf
2016-09-19 21:02 ` Linus Torvalds
2016-09-19 21:07 ` Josh Poimboeuf
2016-09-17 1:25 ` [PATCH v2] scripts: add script for translating stack dump function offsets Peter Zijlstra
2016-09-17 8:15 ` Rabin Vincent
2016-09-17 18:48 ` Josh Poimboeuf
2016-09-17 9:11 ` [PATCH] " Vegard Nossum
2016-09-17 18:54 ` Josh Poimboeuf
2016-09-15 12:47 ` Vince Weaver [this message]
2016-09-15 7:15 ` perf: perf_fuzzer lockup in perf_cgroup_attach Peter Zijlstra
2016-09-15 12:41 ` Vince Weaver
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