[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <ZTd6BYr17ycdHR2a@gmail.com>
Date: Tue, 24 Oct 2023 10:02:13 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Mario Limonciello <mario.limonciello@....com>
Cc: Peter Zijlstra <peterz@...radead.org>,
Borislav Petkov <bp@...en8.de>,
Thomas Gleixner <tglx@...utronix.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Sandipan Das <sandipan.das@....com>,
"H . Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
x86@...nel.org, linux-pm@...r.kernel.org, rafael@...nel.org,
pavel@....cz, linux-perf-users@...r.kernel.org,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>
Subject: Re: [PATCH 2/2] perf/x86/amd: Don't allow pre-emption in
amd_pmu_lbr_reset()
* Mario Limonciello <mario.limonciello@....com> wrote:
> Fixes a BUG reported during suspend to ram testing.
>
> ```
> [ 478.274752] BUG: using smp_processor_id() in preemptible [00000000] code: rtcwake/2948
> [ 478.274754] caller is amd_pmu_lbr_reset+0x19/0xc0
> ```
>
> Cc: stable@...r.kernel.org # 6.1+
> Fixes: ca5b7c0d9621 ("perf/x86/amd/lbr: Add LbrExtV2 branch record support")
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---
> arch/x86/events/amd/lbr.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/events/amd/lbr.c b/arch/x86/events/amd/lbr.c
> index eb31f850841a..5b98e8c7d8b7 100644
> --- a/arch/x86/events/amd/lbr.c
> +++ b/arch/x86/events/amd/lbr.c
> @@ -321,7 +321,7 @@ int amd_pmu_lbr_hw_config(struct perf_event *event)
>
> void amd_pmu_lbr_reset(void)
> {
> - struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
> + struct cpu_hw_events *cpuc = get_cpu_ptr(&cpu_hw_events);
> int i;
>
> if (!x86_pmu.lbr_nr)
> @@ -335,6 +335,7 @@ void amd_pmu_lbr_reset(void)
>
> cpuc->last_task_ctx = NULL;
> cpuc->last_log_id = 0;
> + put_cpu_ptr(&cpu_hw_events);
> wrmsrl(MSR_AMD64_LBR_SELECT, 0);
> }
Weird, amd_pmu_lbr_reset() is called from these places:
- amd_pmu_lbr_sched_task(): during task sched-in during
context-switching, this should already have preemption disabled.
- amd_pmu_lbr_add(): this gets indirectly called by amd_pmu::add
(amd_pmu_add_event()), called by event_sched_in(), which too should have
preemption disabled.
I clearly must have missed some additional place it gets called in.
Could you please cite the full log of the amd_pmu_lbr_reset() call that
caused the critical section warning?
Thanks,
Ingo
Powered by blists - more mailing lists