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

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Date:	Tue, 20 Oct 2015 12:00:10 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	"Liang, Kan" <kan.liang@...el.com>
Cc:	"jolsa@...nel.org" <jolsa@...nel.org>,
	"ak@...ux.intel.com" <ak@...ux.intel.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] perf,tools: fix core dump caused by per-socket/core
 system-wide stat

Em Mon, Oct 19, 2015 at 10:22:51PM +0000, Liang, Kan escreveu:
> Hi Arnaldo
> 
> Here is one more fix for perf/core need to be pulled.

Thanks for the reminder, tried to reproduce on a two socket system,
couldn't, but the fix is obvious enough, thanks, applied.

- Arnaldo
 
> Thanks,
> Kan
> 
> > 
> > On Fri, Oct 09, 2015 at 06:59:23AM -0400, kan.liang@...el.com wrote:
> > > From: Kan Liang <kan.liang@...el.com>
> > >
> > > 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@...el.com>
> > > ---
> > >  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@...nel.org>
> > 
> > thanks,
> > jirka
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