From dcd0b625fe440d68bb4b97c71d18ca48ecd6e594 Mon Sep 17 00:00:00 2001 From: Srinivas Pandruvada Date: Wed, 17 Dec 2025 07:34:55 -0800 Subject: [PATCH] powercap: intel_rapl: Fix possible recursive lock warning With the RAPL PMU addition, there is a recursive locking when CPU online callback function calls rapl_package_add_pmu(). Here cpu_hotplug_lock is already acquired by cpuhp_thread_fun() and rapl_package_add_pmu() tries to acquire again. <4>[ 8.197433] ============================================ <4>[ 8.197437] WARNING: possible recursive locking detected <4>[ 8.197440] 6.19.0-rc1-lgci-xe-xe-4242-05b7c58b3367dca84+ #1 Not tainted <4>[ 8.197444] -------------------------------------------- <4>[ 8.197447] cpuhp/0/20 is trying to acquire lock: <4>[ 8.197450] ffffffff83487870 (cpu_hotplug_lock){++++}-{0:0}, at: rapl_package_add_pmu+0x37/0x370 [intel_rapl_common] <4>[ 8.197463] but task is already holding lock: <4>[ 8.197466] ffffffff83487870 (cpu_hotplug_lock){++++}-{0:0}, at: cpuhp_thread_fun+0x6d/0x290 <4>[ 8.197477] other info that might help us debug this: <4>[ 8.197480] Possible unsafe locking scenario: <4>[ 8.197483] CPU0 <4>[ 8.197485] ---- <4>[ 8.197487] lock(cpu_hotplug_lock); <4>[ 8.197490] lock(cpu_hotplug_lock); <4>[ 8.197493] *** DEADLOCK *** .. .. <4>[ 8.197542] __lock_acquire+0x146e/0x2790 <4>[ 8.197548] lock_acquire+0xc4/0x2c0 <4>[ 8.197550] ? rapl_package_add_pmu+0x37/0x370 [intel_rapl_common] <4>[ 8.197556] cpus_read_lock+0x41/0x110 <4>[ 8.197558] ? rapl_package_add_pmu+0x37/0x370 [intel_rapl_common] <4>[ 8.197561] rapl_package_add_pmu+0x37/0x370 [intel_rapl_common] <4>[ 8.197565] rapl_cpu_online+0x85/0x87 [intel_rapl_msr] <4>[ 8.197568] ? __pfx_rapl_cpu_online+0x10/0x10 [intel_rapl_msr] <4>[ 8.197570] cpuhp_invoke_callback+0x41f/0x6c0 <4>[ 8.197573] ? cpuhp_thread_fun+0x6d/0x290 <4>[ 8.197575] cpuhp_thread_fun+0x1e2/0x290 <4>[ 8.197578] ? smpboot_thread_fn+0x26/0x290 <4>[ 8.197581] smpboot_thread_fn+0x12f/0x290 <4>[ 8.197584] ? __pfx_smpboot_thread_fn+0x10/0x10 <4>[ 8.197586] kthread+0x11f/0x250 <4>[ 8.197589] ? __pfx_kthread+0x10/0x10 <4>[ 8.197592] ret_from_fork+0x344/0x3a0 <4>[ 8.197595] ? __pfx_kthread+0x10/0x10 <4>[ 8.197597] ret_from_fork_asm+0x1a/0x30 <4>[ 8.197604] Fix this issue in the same way as rapl powercap package domain is added from the same CPU online callback by introducing another interface which doesn't call cpus_read_lock(). Add rapl_package_add_pmu_locked() and rapl_package_remove_pmu_locked() which don't call cpus_read_lock(). Fixes: 748d6ba43afd ("powercap: intel_rapl: Enable MSR-based RAPL PMU support") Reported-by: Borah, Chaitanya Kumar Closes: https://lore.kernel.org/linux-pm/5427ede1-57a0-43d1-99f3-8ca4b0643e82@intel.com/T/#u Tested-by: Kuppuswamy Sathyanarayanan Tested-by: RavitejaX Veesam Signed-off-by: Srinivas Pandruvada Link: https://patch.msgid.link/20251217153455.3560176-1-srinivas.pandruvada@linux.intel.com Signed-off-by: Rafael J. Wysocki --- drivers/powercap/intel_rapl_common.c | 24 ++++++++++++++++++------ drivers/powercap/intel_rapl_msr.c | 4 ++-- include/linux/intel_rapl.h | 4 ++++ 3 files changed, 24 insertions(+), 8 deletions(-) diff --git a/drivers/powercap/intel_rapl_common.c b/drivers/powercap/intel_rapl_common.c index b9d87e56cbbc..3ff6da3bf4e6 100644 --- a/drivers/powercap/intel_rapl_common.c +++ b/drivers/powercap/intel_rapl_common.c @@ -2032,7 +2032,7 @@ end: return ret; } -int rapl_package_add_pmu(struct rapl_package *rp) +int rapl_package_add_pmu_locked(struct rapl_package *rp) { struct rapl_package_pmu_data *data = &rp->pmu_data; int idx; @@ -2040,8 +2040,6 @@ int rapl_package_add_pmu(struct rapl_package *rp) if (rp->has_pmu) return -EEXIST; - guard(cpus_read_lock)(); - for (idx = 0; idx < rp->nr_domains; idx++) { struct rapl_domain *rd = &rp->domains[idx]; int domain = rd->id; @@ -2091,17 +2089,23 @@ int rapl_package_add_pmu(struct rapl_package *rp) return rapl_pmu_update(rp); } +EXPORT_SYMBOL_GPL(rapl_package_add_pmu_locked); + +int rapl_package_add_pmu(struct rapl_package *rp) +{ + guard(cpus_read_lock)(); + + return rapl_package_add_pmu_locked(rp); +} EXPORT_SYMBOL_GPL(rapl_package_add_pmu); -void rapl_package_remove_pmu(struct rapl_package *rp) +void rapl_package_remove_pmu_locked(struct rapl_package *rp) { struct rapl_package *pos; if (!rp->has_pmu) return; - guard(cpus_read_lock)(); - list_for_each_entry(pos, &rapl_packages, plist) { /* PMU is still needed */ if (pos->has_pmu && pos != rp) @@ -2111,6 +2115,14 @@ void rapl_package_remove_pmu(struct rapl_package *rp) perf_pmu_unregister(&rapl_pmu.pmu); memset(&rapl_pmu, 0, sizeof(struct rapl_pmu)); } +EXPORT_SYMBOL_GPL(rapl_package_remove_pmu_locked); + +void rapl_package_remove_pmu(struct rapl_package *rp) +{ + guard(cpus_read_lock)(); + + rapl_package_remove_pmu_locked(rp); +} EXPORT_SYMBOL_GPL(rapl_package_remove_pmu); #endif diff --git a/drivers/powercap/intel_rapl_msr.c b/drivers/powercap/intel_rapl_msr.c index 0ce1096b6314..9a7e150b3536 100644 --- a/drivers/powercap/intel_rapl_msr.c +++ b/drivers/powercap/intel_rapl_msr.c @@ -82,7 +82,7 @@ static int rapl_cpu_online(unsigned int cpu) if (IS_ERR(rp)) return PTR_ERR(rp); if (rapl_msr_pmu) - rapl_package_add_pmu(rp); + rapl_package_add_pmu_locked(rp); } cpumask_set_cpu(cpu, &rp->cpumask); return 0; @@ -101,7 +101,7 @@ static int rapl_cpu_down_prep(unsigned int cpu) lead_cpu = cpumask_first(&rp->cpumask); if (lead_cpu >= nr_cpu_ids) { if (rapl_msr_pmu) - rapl_package_remove_pmu(rp); + rapl_package_remove_pmu_locked(rp); rapl_remove_package_cpuslocked(rp); } else if (rp->lead_cpu == cpu) { rp->lead_cpu = lead_cpu; diff --git a/include/linux/intel_rapl.h b/include/linux/intel_rapl.h index e9ade2ff4af6..f479ef5b3341 100644 --- a/include/linux/intel_rapl.h +++ b/include/linux/intel_rapl.h @@ -214,10 +214,14 @@ void rapl_remove_package(struct rapl_package *rp); #ifdef CONFIG_PERF_EVENTS int rapl_package_add_pmu(struct rapl_package *rp); +int rapl_package_add_pmu_locked(struct rapl_package *rp); void rapl_package_remove_pmu(struct rapl_package *rp); +void rapl_package_remove_pmu_locked(struct rapl_package *rp); #else static inline int rapl_package_add_pmu(struct rapl_package *rp) { return 0; } +static inline int rapl_package_add_pmu_locked(struct rapl_package *rp) { return 0; } static inline void rapl_package_remove_pmu(struct rapl_package *rp) { } +static inline void rapl_package_remove_pmu_locked(struct rapl_package *rp) { } #endif #endif /* __INTEL_RAPL_H__ */ -- 2.47.3