linux-kernel - Re: [PATCH 01/20] perf nsinfo: fix refcounting

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Message-ID: <YPCGONcQx5SxEKdY@kernel.org>
Date:   Thu, 15 Jul 2021 16:02:16 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Riccardo Mancini <rickyman7@...il.com>
Cc:     Ian Rogers <irogers@...gle.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Jiri Olsa <jolsa@...hat.com>, linux-kernel@...r.kernel.org,
        linux-perf-users@...r.kernel.org
Subject: Re: [PATCH 01/20] perf nsinfo: fix refcounting

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
stable@...r.kernel.org will figure out which of the supported releases
need each of them.

- Arnaldo
 
> Signed-off-by: Riccardo Mancini <rickyman7@...il.com>
> ---
>  tools/perf/builtin-inject.c   | 5 +++--
>  tools/perf/util/map.c         | 2 ++
>  tools/perf/util/probe-event.c | 4 +++-
>  3 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
> index 5d6f583e2cd35be0..ffd2b25039e36e1d 100644
> --- a/tools/perf/builtin-inject.c
> +++ b/tools/perf/builtin-inject.c
> @@ -361,9 +361,10 @@ static struct dso *findnew_dso(int pid, int tid, const char *filename,
>  		dso = machine__findnew_dso_id(machine, filename, id);
>  	}
>  
> -	if (dso)
> +	if (dso) {
> +		nsinfo__put(dso->nsinfo);
>  		dso->nsinfo = nsi;
> -	else
> +	} else
>  		nsinfo__put(nsi);
>  
>  	thread__put(thread);
> diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
> index 8af693d9678cefe0..72e7f3616157ead4 100644
> --- a/tools/perf/util/map.c
> +++ b/tools/perf/util/map.c
> @@ -192,6 +192,8 @@ struct map *map__new(struct machine *machine, u64 start, u64 len,
>  			if (!(prot & PROT_EXEC))
>  				dso__set_loaded(dso);
>  		}
> +
> +		nsinfo__put(dso->nsinfo);
>  		dso->nsinfo = nsi;
>  
>  		if (build_id__is_defined(bid))
> 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);
> -- 
> 2.31.1
> 

-- 

- Arnaldo