From: Suzuki K Poulose suzuki.poulose@arm.com
commit 730766bae3280a25d40ea76a53dc6342e84e6513 upstream.
During a perf session we try to allocate buffers on the "node" associated with the CPU the event is bound to. If it is not bound to a CPU, we use the current CPU node, using smp_processor_id(). However this is unsafe in a pre-emptible context and could generate the splats as below :
BUG: using smp_processor_id() in preemptible [00000000] code: perf/2544
Use NUMA_NO_NODE hint instead of using the current node for events not bound to CPUs.
Fixes: 2997aa4063d97fdb39 ("coresight: etb10: implementing AUX API") Cc: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com Cc: stable stable@vger.kernel.org # 4.6+ Signed-off-by: Mathieu Poirier mathieu.poirier@linaro.org Link: https://lore.kernel.org/r/20190620221237.3536-5-mathieu.poirier@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/hwtracing/coresight/coresight-etb10.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)
--- a/drivers/hwtracing/coresight/coresight-etb10.c +++ b/drivers/hwtracing/coresight/coresight-etb10.c @@ -373,12 +373,10 @@ static void *etb_alloc_buffer(struct cor struct perf_event *event, void **pages, int nr_pages, bool overwrite) { - int node, cpu = event->cpu; + int node; struct cs_buffers *buf;
- if (cpu == -1) - cpu = smp_processor_id(); - node = cpu_to_node(cpu); + node = (event->cpu == -1) ? NUMA_NO_NODE : cpu_to_node(event->cpu);
buf = kzalloc_node(sizeof(struct cs_buffers), GFP_KERNEL, node); if (!buf)