On Tue, Jan 07, 2020 at 04:08:25PM -0700, Nathan Chancellor wrote:
On Tue, Jan 07, 2020 at 09:55:30PM +0100, Greg Kroah-Hartman wrote:
From: Suzuki K Poulose suzuki.poulose@arm.com
[ Upstream commit 024c1fd9dbcc1d8a847f1311f999d35783921b7f ]
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 Signed-off-by: Sasha Levin sashal@kernel.org
drivers/hwtracing/coresight/coresight-tmc-etf.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c index 336194d059fe..329a201c0c19 100644 --- 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 coresight_device *csdev, int 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);
This breaks the build on 4.14 (and I believe 4.19 from the looks of it) because the event variable is not available without commit a0f08a6a9fee ("coresight: Communicate perf event to sink buffer allocation functions") from upstream. I am not sure how this should be fixed (either backporting the above commit or changing this one somehow) but it should be dropped in the meantime.
Ok, now dropped from both trees, thanks.
greg k-h