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

[Peter Zijlstra]

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.