| Message ID | 20210615050949.10071-1-psampat@linux.ibm.com (mailing list archive) |
|---|---|
| State | Changes Requested, archived |
| Headers | show |
| Series | cpufreq:powernv: Fix init_chip_info initialization in numa=off | expand |
Hello Pratik, On Tue, Jun 15, 2021 at 10:39:49AM +0530, Pratik R. Sampat wrote: > In the numa=off kernel command-line configuration init_chip_info() loops > around the number of chips and attempts to copy the cpumask of that node > which is NULL for all iterations after the first chip. Thanks for taking a look into this. Indeed there is an issue here because the code here assumes that node_mask as a proxy for the chip_mask. This assumption breaks when run with numa=off, since there will only be a single node, but multiple chips. > > Hence adding a check to bail out after the first initialization if there > is only one node. > > Fixes: 053819e0bf84 ("cpufreq: powernv: Handle throttling due to Pmax capping at chip level") > Signed-off-by: Pratik R. Sampat <psampat@linux.ibm.com> > Reported-by: Shirisha Ganta <shirishaganta1@ibm.com> > --- > drivers/cpufreq/powernv-cpufreq.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c > index e439b43c19eb..663f9c4b5e3a 100644 > --- a/drivers/cpufreq/powernv-cpufreq.c > +++ b/drivers/cpufreq/powernv-cpufreq.c > @@ -1078,6 +1078,8 @@ static int init_chip_info(void) > INIT_WORK(&chips[i].throttle, powernv_cpufreq_work_fn); > for_each_cpu(cpu, &chips[i].mask) > per_cpu(chip_info, cpu) = &chips[i]; > + if (num_possible_nodes() == 1) > + break; With this we will only initialize the chip[0].throttle work function, while for the rest of the chips chip[i].throttle will be uninitialized. While we may be running in the numa=off mode, the fact remains that those other chips do exist and they may experiencing throttling, during which they will try to schedule work for chip[i] in order to take corrective action, which will fail. Hence a more correct approach may be to maintain a chip[i] mask independent of the node mask. > } > > free_and_return: > -- > 2.30.2 >
diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c index e439b43c19eb..663f9c4b5e3a 100644 --- a/drivers/cpufreq/powernv-cpufreq.c +++ b/drivers/cpufreq/powernv-cpufreq.c @@ -1078,6 +1078,8 @@ static int init_chip_info(void) INIT_WORK(&chips[i].throttle, powernv_cpufreq_work_fn); for_each_cpu(cpu, &chips[i].mask) per_cpu(chip_info, cpu) = &chips[i]; + if (num_possible_nodes() == 1) + break; } free_and_return:
In the numa=off kernel command-line configuration init_chip_info() loops around the number of chips and attempts to copy the cpumask of that node which is NULL for all iterations after the first chip. Hence adding a check to bail out after the first initialization if there is only one node. Fixes: 053819e0bf84 ("cpufreq: powernv: Handle throttling due to Pmax capping at chip level") Signed-off-by: Pratik R. Sampat <psampat@linux.ibm.com> Reported-by: Shirisha Ganta <shirishaganta1@ibm.com> --- drivers/cpufreq/powernv-cpufreq.c | 2 ++ 1 file changed, 2 insertions(+)