Re: [tip:perf/core] [perf] da916e96e2: BUG:KASAN:null-ptr-deref_in_put_event

[Peter Zijlstra]

On Wed, Apr 16, 2025 at 10:46:10AM +0200, Peter Zijlstra wrote:
> On Tue, Apr 15, 2025 at 04:52:56PM +0100, James Clark wrote:
> > Unrelated to the pointer deref issue, I'm also seeing perf stat not working
> > due to this commit. And that's both with and without this fixup:
> > 
> >  -> perf stat -- true
> > 
> >  Performance counter stats for 'true':
> > 
> >      <not counted> msec task-clock
> > 
> >      <not counted>      context-switches
> > 
> >      <not counted>      cpu-migrations
> > 
> >      <not counted>      page-faults
> > 
> >      <not counted>      armv8_cortex_a53/instructions/
> > 
> >      <not counted>      armv8_cortex_a57/instructions/
> > 
> >      <not counted>      armv8_cortex_a53/cycles/
> > 
> >      <not counted>      armv8_cortex_a57/cycles/
> > 
> >      <not counted>      armv8_cortex_a53/branches/
> > 
> >      <not counted>      armv8_cortex_a53/branch-misses/
> > 
> >      <not counted>      armv8_cortex_a57/branch-misses/
> > 
> > 
> >        0.074139992 seconds time elapsed
> > 
> >        0.000000000 seconds user
> >        0.054797000 seconds sys
> > 
> > Didn't look into it more other than bisecting it to this commit, but I can
> > dig more unless the issue is obvious. This is on Arm big.LITTLE, although I
> > didn't test it elsewhere so I'm not sure if that's relevant or not.
> 
> I can reproduce on x86 alderlake (first machine I tried), so let me go
> have a quick poke.

Could you please try queue.git/perf/core ? I've fixed this and found
another problem.

I'll post the patches tomorrow, after the robot has had a go.