On Tue, Jan 07, 2020 at 09:55:30PM +0100, Greg Kroah-Hartman wrote:
> From: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
>
> [ 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@xxxxxxxxxx>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> Cc: stable <stable@xxxxxxxxxxxxxxx> # 4.7+
> Signed-off-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
> Link: https://lore.kernel.org/r/20190620221237.3536-4-mathieu.poirier@xxxxxxxxxx
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
> 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.
Cheers,
Nathan
