linux-kernel - Re: [RFC v1 01/16] perf kwork: Fix incorrect and missing free atom in work_push

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Message-ID: <ZPisN7/pZrnQeQmK@kernel.org>
Date:   Wed, 6 Sep 2023 13:43:35 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Yang Jihong <yangjihong1@...wei.com>, peterz@...radead.org,
        mingo@...hat.com, mark.rutland@....com,
        alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
        namhyung@...nel.org, adrian.hunter@...el.com,
        kan.liang@...ux.intel.com, sandipan.das@....com,
        ravi.bangoria@....com, linux-kernel@...r.kernel.org,
        linux-perf-users@...r.kernel.org
Subject: Re: [RFC v1 01/16] perf kwork: Fix incorrect and missing free atom
 in work_push_atom()

Em Sun, Sep 03, 2023 at 09:05:06PM -0700, Ian Rogers escreveu:
> On Sat, Aug 12, 2023 at 1:52 AM Yang Jihong <yangjihong1@...wei.com> wrote:
> >
> > 1. Atoms are managed in page mode and should be released using atom_free()
> >    instead of free().
> > 2. When the event does not match, the atom needs to free.
> >
> > Fixes: f98919ec4fcc ("perf kwork: Implement 'report' subcommand")
> > Signed-off-by: Yang Jihong <yangjihong1@...wei.com>
> 
> Reviewed-by: Ian Rogers <irogers@...gle.com>

Thanks, applied locally, will perform some tests and later today
probably push publicly, great work!

- Arnaldo

 
> > ---
> >  tools/perf/builtin-kwork.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/tools/perf/builtin-kwork.c b/tools/perf/builtin-kwork.c
> > index 14bf7a8429e7..73b5dc099a8a 100644
> > --- a/tools/perf/builtin-kwork.c
> > +++ b/tools/perf/builtin-kwork.c
> > @@ -406,12 +406,14 @@ static int work_push_atom(struct perf_kwork *kwork,
> >
> >         work = work_findnew(&class->work_root, &key, &kwork->cmp_id);
> >         if (work == NULL) {
> > -               free(atom);
> > +               atom_free(atom);
> 
> Presumably this is fixing a memory-leak. It would be nice if kwork had
> perf tests, then our builds with -fsanitize=address would highlight
> this kind of issue. Here is a build command I use for this:
> make -C tools/perf O=/tmp/perf DEBUG=1 EXTRA_CFLAGS="-O0 -g
> -fno-omit-frame-pointer -fsanitize=address" BUILD_BPF_SKEL=1
> NO_LIBTRACEEVENT=1
> 
> Thanks,
> Ian
> 
> >                 return -1;
> >         }
> >
> > -       if (!profile_event_match(kwork, work, sample))
> > +       if (!profile_event_match(kwork, work, sample)) {
> > +               atom_free(atom);
> >                 return 0;
> > +       }
> >
> >         if (dst_type < KWORK_TRACE_MAX) {
> >                 dst_atom = list_last_entry_or_null(&work->atom_list[dst_type],
> > --
> > 2.30.GIT
> >

-- 

- Arnaldo