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Date: Wed, 4 Nov 2015 10:26:46 -0300
From: Arnaldo Carvalho de Melo <acme@...radead.org>
To: Jiri Olsa <jolsa@...hat.com>
Cc: Markus Trippelsdorf <markus@...ppelsdorf.de>,
Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Thomas Gleixner <tglx@...utronix.de>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: perf top segfaults on current git
Em Wed, Nov 04, 2015 at 01:27:40PM +0100, Jiri Olsa escreveu:
> On Wed, Nov 04, 2015 at 11:49:30AM +0100, Markus Trippelsdorf wrote:
> > On 2015.11.04 at 11:15 +0100, Markus Trippelsdorf wrote:
> > > On 2015.11.03 at 11:02 +0100, Ingo Molnar wrote:
> > > >
> > > > Please pull the latest perf-core-for-linus git tree from:
> > >
> > > Since the current merge "perf top" segfaults on my machine:
> > >
> > > Program received signal SIGSEGV, Segmentation fault.
> > >
> > > __map__is_kernel (map=map@...ry=0x1abb7a0) at util/map.c:238
> > > 238 return __machine__kernel_map(map->groups->machine, map->type) == map;
> > > (gdb) bt
> > > #0 __map__is_kernel (map=map@...ry=0x1abb7a0) at util/map.c:238
> > > #1 0x00000000004393e4 in symbol_filter (map=map@...ry=0x1abb7a0, sym=sym@...ry=0x1a88560) at builtin-top.c:658
> > > #2 0x00000000004fcd4d in dso__load_sym (dso=dso@...ry=0x166dae0, map=map@...ry=0x1abb7a0, syms_ss=0x7fffffff7680, runtime_ss=runtime_ss@...ry=0x7fffffff7680,
> > > filter=filter@...ry=0x4393c0 <symbol_filter>, kmodule=0) at util/symbol-elf.c:1082
> > > #3 0x00000000004a64e0 in dso__load (dso=0x166dae0, map=map@...ry=0x1abb7a0, filter=filter@...ry=0x4393c0 <symbol_filter>) at util/symbol.c:1530
> > > #4 0x00000000004b941f in map__load (filter=0x4393c0 <symbol_filter>, map=<optimized out>) at util/map.c:289
> > > #5 map__find_symbol (map=0x1abb7a0, addr=40188, filter=0x4393c0 <symbol_filter>) at util/map.c:333
> > > #6 0x00000000004803b1 in perf_event__preprocess_sample (event=event@...ry=0x7ffff6a7a5f0, machine=machine@...ry=0x164c7b8, al=al@...ry=0x7fffffff8a90,
> > > sample=sample@...ry=0x7fffffff8b20) at util/event.c:1045
> > > #7 0x0000000000439837 in perf_event__process_sample (machine=0x164c7b8, sample=0x7fffffff8b20, evsel=0x164c320, event=0x7ffff6a7a5f0, tool=0x7fffffff8ef0)
> > > at builtin-top.c:737
> > > #8 perf_top__mmap_read_idx (top=top@...ry=0x7fffffff8ef0, idx=idx@...ry=0) at builtin-top.c:870
> > > #9 0x000000000043b9ef in perf_top__mmap_read (top=0x7fffffff8ef0) at builtin-top.c:887
> > > #10 __cmd_top (top=0x7fffffff8ef0) at builtin-top.c:1000
> > > #11 cmd_top (argc=<optimized out>, argv=<optimized out>, prefix=<optimized out>) at builtin-top.c:1329
> > > #12 0x00000000004756b3 in run_builtin (p=p@...ry=0x5b0608 <commands+264>, argc=argc@...ry=2, argv=argv@...ry=0x7fffffffe500) at perf.c:386
> > > #13 0x00000000004203e2 in handle_internal_command (argv=0x7fffffffe500, argc=2) at perf.c:447
> > > #14 run_argv (argv=0x7fffffffe290, argcp=0x7fffffffe29c) at perf.c:491
> > > #15 main (argc=2, argv=0x7fffffffe500) at perf.c:608
> > >
> > > It only happens occasionally (~every third or fourth run).
> >
> > Apparently it started with:
> >
> > commit cfc5acd4c80b875d2f739d6a93562034aee5563f
> > Author: Arnaldo Carvalho de Melo <acme@...hat.com>
> > Date: Wed Sep 23 15:15:54 2015 -0300
> >
> > perf top: Filter symbols based on __map__is_kernel(map)
> >
> > Instead of using dso->kernel, this is equivalent at the moment,
> > and helps in reducing the accesses to dso->kernel.
> >
> > Cc: Adrian Hunter <adrian.hunter@...el.com>
> > Cc: Borislav Petkov <bp@...e.de>
> > Cc: David Ahern <dsahern@...il.com>
> > Cc: Frederic Weisbecker <fweisbec@...il.com>
> > Cc: Jiri Olsa <jolsa@...hat.com>
> > Cc: Namhyung Kim <namhyung@...nel.org>
> > Cc: Stephane Eranian <eranian@...gle.com>
> > Cc: Wang Nan <wangnan0@...wei.com>
> > Link: http://lkml.kernel.org/n/tip-1pc2v63iphtifovw3bv0bo1v@git.kernel.org
> > Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
> >
> > diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
> > index bdaf44f24d5d..38d4d6cac823 100644
> > --- a/tools/perf/builtin-top.c
> > +++ b/tools/perf/builtin-top.c
> > @@ -655,7 +655,7 @@ static int symbol_filter(struct map *map, struct symbol *sym)
> > {
> > const char *name = sym->name;
> >
> > - if (!map->dso->kernel)
> > + if (!__map__is_kernel(map))
> > return 0;
> > /*
> > * ppc64 uses function descriptors and appends a '.' to the
> >
>
> I think it's correct to assume map->groups != NULL,
> IMO the change just uncovered another bug
>
> I couldn't reproduce this, but I could find one place where this
> assumption is broken.. could you please try attached patch?
Looks correct, thanks for the quick fix!
- Arnaldo
> thanks,
> jirka
>
>
> ---
> diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
> index 4e38c396a897..afc6b56cf749 100644
> --- a/tools/perf/util/map.c
> +++ b/tools/perf/util/map.c
> @@ -644,6 +644,12 @@ size_t map_groups__fprintf(struct map_groups *mg, FILE *fp)
> return printed;
> }
>
> +static void __map_groups__insert(struct map_groups *mg, struct map *map)
> +{
> + __maps__insert(&mg->maps[map->type], map);
> + map->groups = mg;
> +}
> +
> static int maps__fixup_overlappings(struct maps *maps, struct map *map, FILE *fp)
> {
> struct rb_root *root;
> @@ -682,7 +688,7 @@ static int maps__fixup_overlappings(struct maps *maps, struct map *map, FILE *fp
> }
>
> before->end = map->start;
> - __maps__insert(maps, before);
> + __map_groups__insert(pos->groups, before);
> if (verbose >= 2)
> map__fprintf(before, fp);
> }
> @@ -696,7 +702,7 @@ static int maps__fixup_overlappings(struct maps *maps, struct map *map, FILE *fp
> }
>
> after->start = map->end;
> - __maps__insert(maps, after);
> + __map_groups__insert(pos->groups, after);
> if (verbose >= 2)
> map__fprintf(after, fp);
> }
--
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