| Subject | Re: [PATCH 4.19 102/115] coresight: tmc-etf: Do not call smp_processor_id from preemptible | From | Suzuki Kuruppassery Poulose <> | Date | Wed, 8 Jan 2020 11:00:37 +0000 |
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Hi Greg,
On 07/01/2020 20:55, 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
> 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 e31061308e19..4644ac5582cf 100644 > --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c > +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c > @@ -304,9 +304,7 @@ 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 will break the build on v4.19 to v4.9 as event was not available to the routine. So please drop this one for now. I will post a backport separately.
Suzuki
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