From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Vince Weaver <vincent.weaver@maine.edu>
Cc: Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Namhyung Kim <namhyung@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Jiri Olsa <jolsa@redhat.com>,
Stephane Eranian <eranian@google.com>
Subject: Re: perf: perf_fuzzer crashes on Pentium 4 systems
Date: Thu, 4 Apr 2019 23:20:38 +0300 [thread overview]
Message-ID: <20190404202038.GT1421@uranus.lan> (raw)
In-Reply-To: <alpine.DEB.2.21.1904041454290.5597@macbook-air>
On Thu, Apr 04, 2019 at 03:01:14PM -0400, Vince Weaver wrote:
>
> I do have a lot of this automated already from tracking down past bugs,
> but it turns out that most of the fuzzer-found bugs aren't deterministic
> so it doesn't always work.
>
> For example this bug, while I can easily repeat it, doesn't happen at
> the same time each time. I suspect something corrupts things, but the
> crash doesn't trigger until a context switch happens.
I fear so, I've readin code around to figure out where it might came
from but without much luck yet.
> For what it's worth I've put code in p4_pmu_enable_all() to see what's
> going on when the NULL dereference happens, and sure enough the printk is
> triggered where I'd expect.
>
> [ 138.132889] VMW: p4_pmu_enable_all: idx 4 is NULL
...
>
> the machine still crashes after this, but not right away.
yes, exactly, if look into disasm code we will see that 0x158
offset points to hwc from event. Vince, gimme some time, probably
the weekend so I would dive into the perf code more deeply and
will try to make some debugging patch for more precise tracking
of events. The kernel you're running is the latest -tip?
next prev parent reply other threads:[~2019-04-04 20:20 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-03 14:59 perf: perf_fuzzer crashes on Pentium 4 systems Vince Weaver
2019-04-03 15:13 ` Cyrill Gorcunov
2019-04-03 19:19 ` Cyrill Gorcunov
2019-04-03 20:31 ` Cyrill Gorcunov
2019-04-04 13:25 ` Vince Weaver
2019-04-04 13:33 ` Cyrill Gorcunov
2019-04-04 16:37 ` Vince Weaver
2019-04-04 16:47 ` Cyrill Gorcunov
2019-04-04 19:01 ` Vince Weaver
2019-04-04 20:20 ` Cyrill Gorcunov [this message]
2019-04-07 20:20 ` Cyrill Gorcunov
2019-04-09 16:38 ` Vince Weaver
2019-04-09 17:00 ` Cyrill Gorcunov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190404202038.GT1421@uranus.lan \
--to=gorcunov@gmail.com \
--cc=acme@kernel.org \
--cc=alexander.shishkin@linux.intel.com \
--cc=bp@alien8.de \
--cc=eranian@google.com \
--cc=jolsa@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=namhyung@kernel.org \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=vincent.weaver@maine.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.