short summary: the check for root-only ftrace use is wrong
OK, so after wasting a lot of time on this, the underlying bug is just
that with the settings chosen by the fuzzer, the kernel gets stuck.
The function tracer keeps the CPU busy until interrupted by an interrupt,
which is then traced, b
* Vince Weaver wrote:
> I don't know if there are any better ways to try to debug things
> than the printk route. Though that has its own problems as the
> printk's themselves start showing up in the ftrace traces.
One additional brute-force method is earlyprintk=...,keep and
marking the (h
On Fri, 25 Oct 2013, Vince Weaver wrote:
>
> I'm not sure how tracepoints work exactly, but the problem code is setting
> pe[5].type=PERF_TYPE_TRACEPOINT;
> pe[5].config=0x7fff0001;
>
> The config is being truncated to 32-bits by the perf/ftrace code so I
> think this means
On Fri, 25 Oct 2013, Steven Rostedt wrote:
> On Thu, 2013-10-24 at 14:25 -0400, Vince Weaver wrote:
> > On Thu, 24 Oct 2013, Vince Weaver wrote:
> > > after a month of trying I finally got a small test-case out of my
> > > perf_fuzzer suite that triggers a system lockup with just one syscall.
> >
* Steven Rostedt wrote:
> > Urgh, I had turned those on to try to debug something and forgot
> > to disable. I feel like I saw this problem before I had those
> > enabled so I guess I have to start from scratch fuzzing to see
> > if I can get a more generally reproducible trace.
Btw., even
On Thu, 2013-10-24 at 14:25 -0400, Vince Weaver wrote:
> On Thu, 24 Oct 2013, Vince Weaver wrote:
> > after a month of trying I finally got a small test-case out of my
> > perf_fuzzer suite that triggers a system lockup with just one syscall.
> >
> > Attached is the code that triggers it.
>
> An
On Thu, 24 Oct 2013, Vince Weaver wrote:
> after a month of trying I finally got a small test-case out of my
> perf_fuzzer suite that triggers a system lockup with just one syscall.
>
> Attached is the code that triggers it.
And it turns out you can only trigger this specific problem if advanced
Hello
after a month of trying I finally got a small test-case out of my
perf_fuzzer suite that triggers a system lockup with just one syscall.
Attached is the code that triggers it.
I tried tracking through the ftrace code to find out what's going on, but
I quickly get lost. The perf/ftrace c
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