Re: [PATCH 1/1] perf,tools: fix core dump caused by per-socket/core system-wide stat

[Jiri Olsa]

On Fri, Oct 09, 2015 at 06:59:23AM -0400, kan.liang@xxxxxxxxx wrote:
> From: Kan Liang <kan.liang@xxxxxxxxx>
> 
> Perf will core dump if --per-socket/core -a are applied for perf stat.
> 
> The root cause is that cpu_map__build_map set refcnt of evlist's cpu_map
> to 1.
> It should set refcnt for the newly created cpu_map, not evlist's
> cpu_map.
> 
> Here is the example:
> 
> perf stat -e cycles --per-socket -a sleep 1
> 
>  Performance counter stats for 'system wide':
> 
> S0       36         30,196,257      cycles
> S1       28         15,823,536      cycles
> 
>        1.001126828 seconds time elapsed
> 
> *** Error in `./perf': corrupted double-linked list: 0x00000000021f9090
> ***
> ======= Backtrace: =========
> /lib64/libc.so.6[0x3002e7bbe7]
> /lib64/libc.so.6[0x3002e7d2b5]
> ./perf(perf_evsel__delete+0x28)[0x485bdd]
> ./perf[0x4800e8]
> ./perf(perf_evlist__delete+0x5e)[0x482cd5]
> ./perf(cmd_stat+0xf25)[0x432328]
> ./perf[0x4768e0]
> ./perf[0x476ad6]
> ./perf[0x476b41]
> ./perf(main+0x1d0)[0x476db2]
> /lib64/libc.so.6(__libc_start_main+0xf5)[0x3002e21b45]
> ./perf[0x4202c5]
> 
> Signed-off-by: Kan Liang <kan.liang@xxxxxxxxx>
> ---
>  tools/perf/util/cpumap.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c
> index c51c29f..dfc1f0b 100644
> --- a/tools/perf/util/cpumap.c
> +++ b/tools/perf/util/cpumap.c
> @@ -284,7 +284,7 @@ static int cpu_map__build_map(struct cpu_map *cpus, struct cpu_map **res,
>  	/* ensure we process id in increasing order */
>  	qsort(c->map, c->nr, sizeof(int), cmp_ids);
>  
> -	atomic_set(&cpus->refcnt, 1);
> +	atomic_set(&c->refcnt, 1);

ouch ;-) 

Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>

thanks,
jirka
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