Commit
8a58ddae2379 ("perf/core: Fix exclusive events' grouping")
allows CAP_EXCLUSIVE events to be grouped with other events. Since all of those also happen to be AUX events (which is not the case the other way around, because arch/s390), this changes the rules for stopping the output: the AUX event may not be on its PMU's context any more, if it's grouped with a HW event, in which case it will be on that HW event's context instead. If that's the case, munmap() of the AUX buffer can't find and stop the AUX event, potentially leaving the last reference with the atomic context, which will then end up freeing the AUX buffer. This will then trip warnings:
WARNING: CPU: 2 PID: 318 at kernel/events/core.c:5615 perf_mmap_close+0x839/0x850 Modules linked in: CPU: 2 PID: 318 Comm: exclusive-group Tainted: G W 5.4.0-rc3-00070-g39b656ee9f2c #846 RIP: 0010:perf_mmap_close+0x839/0x850
Fix this by using the context's PMU context when looking for events to stop, instead of the event's PMU context.
Signed-off-by: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: stable@vger.kernel.org --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c index 5bbaabdad068..77793ef0d8bc 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6965,7 +6965,7 @@ static void __perf_event_output_stop(struct perf_event *event, void *data) static int __perf_pmu_output_stop(void *info) { struct perf_event *event = info; - struct pmu *pmu = event->pmu; + struct pmu *pmu = event->ctx->pmu; struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context); struct remote_output ro = { .rb = event->rb,
The following commit has been merged into the perf/urgent branch of tip:
Commit-ID: f3a519e4add93b7b31a6616f0b09635ff2e6a159 Gitweb: https://git.kernel.org/tip/f3a519e4add93b7b31a6616f0b09635ff2e6a159 Author: Alexander Shishkin alexander.shishkin@linux.intel.com AuthorDate: Tue, 22 Oct 2019 10:39:40 +03:00 Committer: Ingo Molnar mingo@kernel.org CommitterDate: Tue, 22 Oct 2019 14:39:37 +02:00
perf/aux: Fix AUX output stopping
Commit:
8a58ddae2379 ("perf/core: Fix exclusive events' grouping")
allows CAP_EXCLUSIVE events to be grouped with other events. Since all of those also happen to be AUX events (which is not the case the other way around, because arch/s390), this changes the rules for stopping the output: the AUX event may not be on its PMU's context any more, if it's grouped with a HW event, in which case it will be on that HW event's context instead. If that's the case, munmap() of the AUX buffer can't find and stop the AUX event, potentially leaving the last reference with the atomic context, which will then end up freeing the AUX buffer. This will then trip warnings:
Fix this by using the context's PMU context when looking for events to stop, instead of the event's PMU context.
Signed-off-by: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Arnaldo Carvalho de Melo acme@redhat.com Cc: Jiri Olsa jolsa@redhat.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra a.p.zijlstra@chello.nl Cc: Peter Zijlstra peterz@infradead.org Cc: Stephane Eranian eranian@google.com Cc: Thomas Gleixner tglx@linutronix.de Cc: Vince Weaver vincent.weaver@maine.edu Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20191022073940.61814-1-alexander.shishkin@linux.in... Signed-off-by: Ingo Molnar mingo@kernel.org --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c index f5d7950..bb3748d 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6949,7 +6949,7 @@ static void __perf_event_output_stop(struct perf_event *event, void *data) static int __perf_pmu_output_stop(void *info) { struct perf_event *event = info; - struct pmu *pmu = event->pmu; + struct pmu *pmu = event->ctx->pmu; struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context); struct remote_output ro = { .rb = event->rb,
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