From c03791085adcd61fa9b766ab303c7d0941d7378d Mon Sep 17 00:00:00 2001 From: K Prateek Nayak Date: Mon, 16 Mar 2026 08:18:49 +0000 Subject: cpufreq: Pass the policy to cpufreq_driver->adjust_perf() cpufreq_cpu_get() can sleep on PREEMPT_RT in presence of concurrent writer(s), however amd-pstate depends on fetching the cpudata via the policy's driver data which necessitates grabbing the reference. Since schedutil governor can call "cpufreq_driver->update_perf()" during sched_tick/enqueue/dequeue with rq_lock held and IRQs disabled, fetching the policy object using the cpufreq_cpu_get() helper in the scheduler fast-path leads to "BUG: scheduling while atomic" on PREEMPT_RT [1]. Pass the cached cpufreq policy object in sg_policy to the update_perf() instead of just the CPU. The CPU can be inferred using "policy->cpu". The lifetime of cpufreq_policy object outlasts that of the governor and the cpufreq driver (allocated when the CPU is onlined and only reclaimed when the CPU is offlined / the CPU device is removed) which makes it safe to be referenced throughout the governor's lifetime. Closes:https://lore.kernel.org/all/20250731092316.3191-1-spasswolf@web.de/ [1] Fixes: 1d215f0319c2 ("cpufreq: amd-pstate: Add fast switch function for AMD P-State") Reported-by: Bert Karwatzki Acked-by: Viresh Kumar Signed-off-by: K Prateek Nayak Acked-by: Gary Guo # Rust Reviewed-by: Gautham R. Shenoy Reviewed-by: Zhongqiu Han Link: https://lore.kernel.org/r/20260316081849.19368-3-kprateek.nayak@amd.com Signed-off-by: Mario Limonciello (AMD) --- include/linux/cpufreq.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index cc894fc38971..4317c5a312bd 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -372,7 +372,7 @@ struct cpufreq_driver { * conditions) scale invariance can be disabled, which causes the * schedutil governor to fall back to the latter. */ - void (*adjust_perf)(unsigned int cpu, + void (*adjust_perf)(struct cpufreq_policy *policy, unsigned long min_perf, unsigned long target_perf, unsigned long capacity); @@ -617,7 +617,7 @@ struct cpufreq_governor { /* Pass a target to the cpufreq driver */ unsigned int cpufreq_driver_fast_switch(struct cpufreq_policy *policy, unsigned int target_freq); -void cpufreq_driver_adjust_perf(unsigned int cpu, +void cpufreq_driver_adjust_perf(struct cpufreq_policy *policy, unsigned long min_perf, unsigned long target_perf, unsigned long capacity); -- cgit v1.2.3