Re: [stable] [PATCH 1/2] coresight: etb10: Do not call smp_processor_id from preemptible

From: Sasha Levin
Date: Thu Jan 09 2020 - 09:35:41 EST


On Wed, Jan 08, 2020 at 11:05:40AM +0000, Suzuki K Poulose wrote:
[ Upstream commit 730766bae3280a25d40ea76a53dc6342e84e6513 ]

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@xxxxxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx> # v4.9 to v4.19
Signed-off-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20190620221237.3536-5-mathieu.poirier@xxxxxxxxxx

I've queued this for 4.9-4.19. There was a simple conflict on 4.9 which
also had to be resolved.

--
Thanks,
Sasha