Messages in this thread Patch in this message | | | From | Namhyung Kim <> | Subject | [RFC] perf/x86: Fix a warning on x86_pmu_stop() | Date | Sat, 21 Nov 2020 11:50:11 +0900 |
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When large PEBS is enabled, the below warning is triggered:
[6070379.453697] WARNING: CPU: 23 PID: 42379 at arch/x86/events/core.c:1466 x86_pmu_stop+0x95/0xa0 ... [6070379.453831] Call Trace: [6070379.453840] x86_pmu_del+0x50/0x150 [6070379.453845] event_sched_out.isra.0+0x95/0x200 [6070379.453848] group_sched_out.part.0+0x53/0xd0 [6070379.453851] __perf_event_disable+0xee/0x1e0 [6070379.453854] event_function+0x89/0xd0 [6070379.453859] remote_function+0x3e/0x50 [6070379.453866] generic_exec_single+0x91/0xd0 [6070379.453870] smp_call_function_single+0xd1/0x110 [6070379.453874] event_function_call+0x11c/0x130 [6070379.453877] ? task_ctx_sched_out+0x20/0x20 [6070379.453880] ? perf_mux_hrtimer_handler+0x370/0x370 [6070379.453882] ? event_function_call+0x130/0x130 [6070379.453886] perf_event_for_each_child+0x34/0x80 [6070379.453889] ? event_function_call+0x130/0x130 [6070379.453891] _perf_ioctl+0x24b/0x6a0 [6070379.453898] ? sched_setaffinity+0x1ad/0x2a0 [6070379.453904] ? _cond_resched+0x15/0x30 [6070379.453906] perf_ioctl+0x3d/0x60 [6070379.453912] ksys_ioctl+0x87/0xc0 [6070379.453917] __x64_sys_ioctl+0x16/0x20 [6070379.453923] do_syscall_64+0x52/0x180 [6070379.453928] entry_SYSCALL_64_after_hwframe+0x44/0xa9
The commit 3966c3feca3f ("x86/perf/amd: Remove need to check "running" bit in NMI handler") introduced this. It seems x86_pmu_stop can be called recursively (like when it losts some samples) like below:
x86_pmu_stop intel_pmu_disable_event (x86_pmu_disable) intel_pmu_pebs_disable intel_pmu_drain_pebs_buffer x86_pmu_stop
It seems the change is only needed for AMD. So I added a new bit to check when it should clear the active mask.
Fixes: 3966c3feca3f ("x86/perf/amd: Remove need to check "running" bit in NMI handler") Reported-by: John Sperbeck <jsperbeck@google.com> Cc: "Lendacky, Thomas" <Thomas.Lendacky@amd.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org> --- arch/x86/events/amd/core.c | 1 + arch/x86/events/core.c | 9 +++++++-- arch/x86/events/perf_event.h | 3 ++- 3 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c index 39eb276d0277..c545fbd423df 100644 --- a/arch/x86/events/amd/core.c +++ b/arch/x86/events/amd/core.c @@ -927,6 +927,7 @@ static __initconst const struct x86_pmu amd_pmu = { .max_period = (1ULL << 47) - 1, .get_event_constraints = amd_get_event_constraints, .put_event_constraints = amd_put_event_constraints, + .late_nmi = 1, .format_attrs = amd_format_attr, .events_sysfs_show = amd_event_sysfs_show, diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index 7b802a778014..a6c12bd71e66 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -1514,8 +1514,13 @@ void x86_pmu_stop(struct perf_event *event, int flags) struct hw_perf_event *hwc = &event->hw; if (test_bit(hwc->idx, cpuc->active_mask)) { - x86_pmu.disable(event); - __clear_bit(hwc->idx, cpuc->active_mask); + if (x86_pmu.late_nmi) { + x86_pmu.disable(event); + __clear_bit(hwc->idx, cpuc->active_mask); + } else { + __clear_bit(hwc->idx, cpuc->active_mask); + x86_pmu.disable(event); + } cpuc->events[hwc->idx] = NULL; WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED); hwc->state |= PERF_HES_STOPPED; diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h index 10032f023fcc..1ffaa0fcd521 100644 --- a/arch/x86/events/perf_event.h +++ b/arch/x86/events/perf_event.h @@ -682,7 +682,8 @@ struct x86_pmu { /* PMI handler bits */ unsigned int late_ack :1, enabled_ack :1, - counter_freezing :1; + counter_freezing :1, + late_nmi :1; /* * sysfs attrs */ -- 2.29.2.454.gaff20da3a2-goog
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