Dear All, On 14.03.2024 09:39, Catalin Marinas wrote: > On Wed, Mar 13, 2024 at 05:13:33PM +0000, Russell King wrote: >> So, I wonder whether what you're seeing is a latent bug which is >> being tickled by the presence of the CPU masks being off-stack >> changing the kernel timing. >> >> I would suggest the printk debug approach may help here to see when >> the OPPs are begun to be parsed, when they're created etc and their >> timing relationship to being used. Given the suspicion, it's possible >> that the mere addition of printk() may "fix" the problem, which again >> would be another semi-useful data point. > It might be an init order problem. Passing "initcall_debug" on the > cmdline might help a bit. > > It would also be useful in dev_pm_opp_set_config(), in the WARN_ON > block, to print opp_table->opp_list.next to get an idea whether it looks > like a valid pointer or memory corruption. I've finally found some time to do the step-by-step printk-based debugging of this issue and finally found what's broken! Here is the fix: diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c index 8bd6e5e8f121..2d83bbc65dd0 100644 --- a/drivers/cpufreq/cpufreq-dt.c +++ b/drivers/cpufreq/cpufreq-dt.c @@ -208,7 +208,7 @@ static int dt_cpufreq_early_init(struct device *dev, int cpu) if (!priv) return -ENOMEM; - if (!alloc_cpumask_var(&priv->cpus, GFP_KERNEL)) + if (!zalloc_cpumask_var(&priv->cpus, GFP_KERNEL)) return -ENOMEM; cpumask_set_cpu(cpu, priv->cpus); It is really surprising that this didn't blow up for anyone else so far... This means that the $subject patch is fine. I will send a proper patch fixing this issue in a few minutes. Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland
