Re: [PATCH] perf evlist: fix memory corruption for Kernel PMU event

[Jiri Olsa]

On Tue, Oct 06, 2020 at 06:39:44AM +0000, Song Bao Hua (Barry Song) wrote:

SNIP

> > > Andi, thanks! Could you share the link or the commit ID? I'd like to take a
> > look at the fix.
> > > I could still reproduce this issue in the latest linus' tree and I didn't find any
> > commit
> > > related to this issue in linux-next and tip/perf/core.
> > 
> > I think Andi was referring to this discussion which is not merged yet:
> > 
> > https://lore.kernel.org/lkml/20200922031346.15051-2-liwei391@xxxxxxxxx
> > m/
> > 
> > I suggested a patch at the end.  Can you please try it?
> 
> I tried the patch you suggested.
> 
> diff --git a/tools/lib/perf/evlist.c b/tools/lib/perf/evlist.c
> index 2208444ecb44..cfcdbd7be066 100644
> --- a/tools/lib/perf/evlist.c
> +++ b/tools/lib/perf/evlist.c
> @@ -45,6 +45,9 @@ static void __perf_evlist__propagate_maps(struct perf_evlist *evlist,
>          if (!evsel->own_cpus || evlist->has_user_cpus) {
>                  perf_cpu_map__put(evsel->cpus);
>                 evsel->cpus = perf_cpu_map__get(evlist->cpus);
> +       } else if (!evsel->system_wide && perf_cpu_map__empty(evlist->cpus)) {
> +               perf_cpu_map__put(evsel->cpus);
> +               evsel->cpus = perf_cpu_map__get(evlist->cpus);
>         } else if (evsel->cpus != evsel->own_cpus) {
>                 perf_cpu_map__put(evsel->cpus);
>                 evsel->cpus = perf_cpu_map__get(evsel->own_cpus);
> 
> it did fix the crash I have seen on arm64. I'd prefer you put the below fixes tag in the commit log. 
> Fixes: 7736627b865d ("perf stat: Use affinity for closing file descriptors")
> Perf stat began to crash from v5.4 kernel, so the fix should be backported to stable trees.

awesome.. Namhyung, could you please send full patch?

thanks,
jirka