2021-07-15 19:54:54

by Arnaldo Carvalho de Melo

[permalink] [raw]
Subject: Re: [PATCH 01/20] perf nsinfo: fix refcounting

Em Thu, Jul 15, 2021 at 04:02:16PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Thu, Jul 15, 2021 at 06:07:06PM +0200, Riccardo Mancini escreveu:
> > ASan reports a memory leak of nsinfo during the execution of the perf
> > test "31: Lookup mmap thread".
> > The leak is caused by a refcounted variable being replaced without
> > dropping the refcount.
> >
> > This patch makes sure that the refcnt of nsinfo is decreased whenever
> > a refcounted variable is replaced with a new value.
>
> So, there are multiple fixes in just one patch, I'll split it into
> three, no need to resend.
>
> I'll try and check if finding Fixes: for the three is easy, that way
> [email protected] will figure out which of the supported releases
> need each of them.

3rd:

commit 7416120498f83963f4c5662847a1a0556e771b89
Author: Riccardo Mancini <[email protected]>
Date: Thu Jul 15 18:07:06 2021 +0200

perf probe: Fix dso->nsinfo refcounting

ASan reports a memory leak of nsinfo during the execution of:

# perf test "31: Lookup mmap thread".

The leak is caused by a refcounted variable being replaced without
dropping the refcount.

This patch makes sure that the refcnt of nsinfo is decreased whenever
a refcounted variable is replaced with a new value.

Signed-off-by: Riccardo Mancini <[email protected]>
Fixes: 544abd44c7064c8a ("perf probe: Allow placing uprobes in alternate namespaces.")
Cc: Ian Rogers <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Krister Johansen <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lore.kernel.org/lkml/55223bc8821b34ccb01f92ef1401c02b6a32e61f.1626343282.git.rickyman7@gmail.com
[ Split from a larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index c14e1d228e56b1c6..e05750cea34c3a95 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -179,8 +179,10 @@ struct map *get_target_map(const char *target, struct nsinfo *nsi, bool user)
struct map *map;

map = dso__new_map(target);
- if (map && map->dso)
+ if (map && map->dso) {
+ nsinfo__put(map->dso->nsinfo);
map->dso->nsinfo = nsinfo__get(nsi);
+ }
return map;
} else {
return kernel_get_module_map(target);