If one thread mmaps a perf event while another thread in the same mm is in some context where active_mm != mm (which can happen in the scheduler, for example), refresh_pce() would write the wrong value to CR4.PCE. This broke some PAPI tests. Cc: stable@xxxxxxxxxxxxxxx Fixes: 7911d3f7af14 ("perf/x86: Only allow rdpmc if a perf_event is mapped") Reported-and-tested-by: Vince Weaver <vincent.weaver@xxxxxxxxx> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx> --- arch/x86/events/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index 349d4d17aa7f..4f564df73b8f 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2101,8 +2101,8 @@ static int x86_pmu_event_init(struct perf_event *event) static void refresh_pce(void *ignored) { - if (current->mm) - load_mm_cr4(current->mm); + if (current->active_mm) + load_mm_cr4(current->active_mm); } static void x86_pmu_event_mapped(struct perf_event *event) -- 2.9.3