Re: [PATCH] cpufreq:powernv: Fix init_chip_info initialization in numa=off
flat view
From: Gautham R Shenoy <hidden>
Date: 2021-07-08 09:08:31
Also in:
linux-pm, lkml
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.
quoted hunk ↗ jump to hunk
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 <redacted> Reported-by: Shirisha Ganta <redacted> --- 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