On Wed, Nov 04, 2015 at 01:41:37PM +0100, Markus Trippelsdorf wrote: SNIP
> > > Apparently it started with: > > > > > > commit cfc5acd4c80b875d2f739d6a93562034aee5563f > > > Author: Arnaldo Carvalho de Melo <[email protected]> > > > Date: Wed Sep 23 15:15:54 2015 -0300 > > > > > > perf top: Filter symbols based on __map__is_kernel(map) > > > > 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? > > Your patch fixes the issue. > Thanks. thanks, sending patch jirka --- When new maps are cloned out of split map they are added into origin map's group, but their groups pointer is not updated. This could lead to segfault, because map::groups is expected to be always set as reported by Markus: __map__is_kernel (map=map@entry=0x1abb7a0) at util/map.c:238 238 return __machine__kernel_map(map->groups->machine, map->type) = (gdb) bt #0 __map__is_kernel (map=map@entry=0x1abb7a0) at util/map.c:238 #1 0x00000000004393e4 in symbol_filter (map=map@entry=0x1abb7a0, sym=sym@entry #2 0x00000000004fcd4d in dso__load_sym (dso=dso@entry=0x166dae0, map=map@entry #3 0x00000000004a64e0 in dso__load (dso=0x166dae0, map=map@entry=0x1abb7a0, fi #4 0x00000000004b941f in map__load (filter=0x4393c0 <symbol_filter>, map=<opti #5 map__find_symbol (map=0x1abb7a0, addr=40188, filter=0x4393c0 <symbol_filter ... Adding __map_groups__insert function to add map into groups together with map::groups pointer update. It takes no lock as opposed to existing map_groups__insert. Using __map_groups__insert to add new maps after map split. Reported-by: Markus Trippelsdorf <[email protected]> Tested-by: Markus Trippelsdorf <[email protected]> Link: http://lkml.kernel.org/n/[email protected] Signed-off-by: Jiri Olsa <[email protected]> --- tools/perf/util/map.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) 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); } -- 2.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
