From: Suzuki K Poulose suzuki.poulose@arm.com
commit 024c1fd9dbcc1d8a847f1311f999d35783921b7f 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 caller is tmc_alloc_etf_buffer+0x5c/0x60 CPU: 2 PID: 2544 Comm: perf Not tainted 5.1.0-rc6-147786-g116841e #344 Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Feb 1 2019 Call trace: dump_backtrace+0x0/0x150 show_stack+0x14/0x20 dump_stack+0x9c/0xc4 debug_smp_processor_id+0x10c/0x110 tmc_alloc_etf_buffer+0x5c/0x60 etm_setup_aux+0x1c4/0x230 rb_alloc_aux+0x1b8/0x2b8 perf_mmap+0x35c/0x478 mmap_region+0x34c/0x4f0 do_mmap+0x2d8/0x418 vm_mmap_pgoff+0xd0/0xf8 ksys_mmap_pgoff+0x88/0xf8 __arm64_sys_mmap+0x28/0x38 el0_svc_handler+0xd8/0x138 el0_svc+0x8/0xc
Use NUMA_NO_NODE hint instead of using the current node for events not bound to CPUs.
Fixes: 2e499bbc1a929ac ("coresight: tmc: implementing TMC-ETF AUX space API") Cc: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com Cc: stable stable@vger.kernel.org # 4.7+ Signed-off-by: Mathieu Poirier mathieu.poirier@linaro.org Link: https://lore.kernel.org/r/20190620221237.3536-4-mathieu.poirier@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/hwtracing/coresight/coresight-tmc-etf.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c @@ -308,9 +308,7 @@ static void *tmc_alloc_etf_buffer(struct int node; struct cs_buffers *buf;
- if (cpu == -1) - cpu = smp_processor_id(); - node = cpu_to_node(cpu); + node = (cpu == -1) ? NUMA_NO_NODE : cpu_to_node(cpu);
/* Allocate memory structure for interaction with Perf */ buf = kzalloc_node(sizeof(struct cs_buffers), GFP_KERNEL, node);