diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-01-24 09:24:17 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-01-24 09:24:17 -0800 |
| commit | ceaeaf66a21f87febed73ec2051f9384390efe2f (patch) | |
| tree | 8e6c875a67e7c28ae3e67015beaf8469039b90ed | |
| parent | dc67a355058087792abd4e7fd9af22ef4a86cefe (diff) | |
| parent | 91dcfae0ff2b9b9ab03c1ec95babaceefbffb9f4 (diff) | |
Merge tag 'perf-urgent-2026-01-24' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf events fixes from Ingo Molnar:
- Fix mmap_count warning & bug when creating a group member event
with the PERF_FLAG_FD_OUTPUT flag
- Disable the sample period == 1 branch events BTS optimization
on guests, because BTS is not virtualized
* tag 'perf-urgent-2026-01-24' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86/intel: Do not enable BTS for guests
perf: Fix refcount warning on event->mmap_count increment
| -rw-r--r-- | arch/x86/events/perf_event.h | 13 | ||||
| -rw-r--r-- | kernel/events/core.c | 9 |
2 files changed, 20 insertions, 2 deletions
diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h index 62963022b517..ad35c546243e 100644 --- a/arch/x86/events/perf_event.h +++ b/arch/x86/events/perf_event.h @@ -1574,13 +1574,22 @@ static inline bool intel_pmu_has_bts_period(struct perf_event *event, u64 period struct hw_perf_event *hwc = &event->hw; unsigned int hw_event, bts_event; - if (event->attr.freq) + /* + * Only use BTS for fixed rate period==1 events. + */ + if (event->attr.freq || period != 1) + return false; + + /* + * BTS doesn't virtualize. + */ + if (event->attr.exclude_host) return false; hw_event = hwc->config & INTEL_ARCH_EVENT_MASK; bts_event = x86_pmu.event_map(PERF_COUNT_HW_BRANCH_INSTRUCTIONS); - return hw_event == bts_event && period == 1; + return hw_event == bts_event; } static inline bool intel_pmu_has_bts(struct perf_event *event) diff --git a/kernel/events/core.c b/kernel/events/core.c index 5b5cb620499e..a0fa488bce84 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6997,6 +6997,15 @@ static int perf_mmap_rb(struct vm_area_struct *vma, struct perf_event *event, if (data_page_nr(event->rb) != nr_pages) return -EINVAL; + /* + * If this event doesn't have mmap_count, we're attempting to + * create an alias of another event's mmap(); this would mean + * both events will end up scribbling the same user_page; + * which makes no sense. + */ + if (!refcount_read(&event->mmap_count)) + return -EBUSY; + if (refcount_inc_not_zero(&event->rb->mmap_count)) { /* * Success -- managed to mmap() the same buffer |