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

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Message-ID: <YPCHYiZexSnyTnYg@kernel.org>
Date:   Thu, 15 Jul 2021 16:07:14 -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 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
> stable@...r.kernel.org will figure out which of the supported releases
> need each of them.

The first patch becomes:

commit b36bbdefec297ee5b6e278904360ad14fa3b09de
Author: Riccardo Mancini <rickyman7@...il.com>
Date:   Thu Jul 15 18:07:06 2021 +0200

    perf inject: Fix dso->nsinfo refcounting
    
    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 when a
    refcounted variable is replaced with a new value.
    
    Signed-off-by: Riccardo Mancini <rickyman7@...il.com>
    Fixes: 27c9c3424fc217da ("perf inject: Add --buildid-all option")
    Cc: Ian Rogers <irogers@...gle.com>
    Cc: Jiri Olsa <jolsa@...hat.com>
    Cc: Mark Rutland <mark.rutland@....com>
    Cc: Namhyung Kim <namhyung@...nel.org>
    Cc: Peter Zijlstra <peterz@...radead.org>
    Link: http://lore.kernel.org/lkml/55223bc8821b34ccb01f92ef1401c02b6a32e61f.1626343282.git.rickyman7@gmail.com
    [ Split from a larger patch ]
    Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>

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);