On Fri, Sep 11, 2020 at 4:49 PM Jiri Olsa <[email protected]> wrote: > ugh, that's right.. how about change below
Acked-by: Namhyung Kim <[email protected]> Thanks Namhyung > > jirka > > > --- > diff --git a/kernel/events/core.c b/kernel/events/core.c > index 7ed5248f0445..8ab2400aef55 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -5868,11 +5868,11 @@ static void perf_pmu_output_stop(struct perf_event > *event); > static void perf_mmap_close(struct vm_area_struct *vma) > { > struct perf_event *event = vma->vm_file->private_data; > - > struct perf_buffer *rb = ring_buffer_get(event); > struct user_struct *mmap_user = rb->mmap_user; > int mmap_locked = rb->mmap_locked; > unsigned long size = perf_data_size(rb); > + bool detach_rest = false; > > if (event->pmu->event_unmapped) > event->pmu->event_unmapped(event, vma->vm_mm); > @@ -5903,7 +5903,8 @@ static void perf_mmap_close(struct vm_area_struct *vma) > mutex_unlock(&event->mmap_mutex); > } > > - atomic_dec(&rb->mmap_count); > + if (atomic_dec_and_test(&rb->mmap_count)) > + detach_rest = true; > > if (!atomic_dec_and_mutex_lock(&event->mmap_count, > &event->mmap_mutex)) > goto out_put; > @@ -5912,7 +5913,7 @@ static void perf_mmap_close(struct vm_area_struct *vma) > mutex_unlock(&event->mmap_mutex); > > /* If there's still other mmap()s of this buffer, we're done. */ > - if (atomic_read(&rb->mmap_count)) > + if (!detach_rest) > goto out_put; > > /* >
