kernel.git/kernel/power/energy_model.c, branch linux-rolling-stable

PM: EM: Fix memory leak in em_create_pd() error path

2026-01-08T15:55:21Z

When ida_alloc() fails in em_create_pd(), the function returns without freeing the previously allocated 'pd' structure, leading to a memory leak. The 'pd' pointer is allocated either at line 436 (for CPU devices with cpumask) or line 442 (for other devices) using kzalloc(). Additionally, the function incorrectly returns -ENOMEM when ida_alloc() fails, ignoring the actual error code returned by ida_alloc(), which can fail for reasons other than memory exhaustion. Fix both issues by: 1. Freeing the 'pd' structure with kfree() when ida_alloc() fails 2. Returning the actual error code from ida_alloc() instead of -ENOMEM This ensures proper cleanup on the error path and accurate error reporting. Fixes: cbe5aeedecc7 ("PM: EM: Assign a unique ID when creating a performance domain") Signed-off-by: Malaya Kumar Rout Reviewed-by: Changwoo Min Link: https://patch.msgid.link/20260105103730.65626-1-mrout@redhat.com Signed-off-by: Rafael J. Wysocki

PM: EM: Add to em_pd_list only when no failure

2025-10-29T12:37:00Z

When em_create_perf_table() returns failure, pd is freed, there dev->em_pd is not valid. Then accessing dev->em_pd->node will trigger kernel panic in em_dev_register_pd_no_update(). So return early if 'ret' is non-zero. Kernel dump: cpu cpu0: EM: invalid power: 0 Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008 Mem abort info: pc : em_dev_register_pd_no_update+0xb4/0x79c lr : em_dev_register_pd_no_update+0x9c/0x79c Call trace: em_dev_register_pd_no_update+0xb4/0x79c (P) em_dev_register_perf_domain+0x18/0x58 scmi_cpufreq_register_em+0x84/0xb8 cpufreq_online+0x48c/0xb74 cpufreq_add_dev+0x80/0x98 subsys_interface_register+0x100/0x11c cpufreq_register_driver+0x158/0x278 scmi_cpufreq_probe+0x1f8/0x2e0 scmi_dev_probe+0x28/0x3c really_probe+0xbc/0x29c __driver_probe_device+0x78/0x12c driver_probe_device+0x3c/0x15c __device_attach_driver+0xb8/0x134 bus_for_each_drv+0x84/0xe4 Fixes: cbe5aeedecc7 ("PM: EM: Assign a unique ID when creating a performance domain") Signed-off-by: Peng Fan Reviewed-by: Changwoo Min Reviewed-by: Lukasz Luba Link: https://patch.msgid.link/20251028-fix-energy-v1-1-ab854fd6a97c@nxp.com Signed-off-by: Rafael J. Wysocki

PM: EM: Notify an event when the performance domain changes

2025-10-22T19:44:38Z

Send an event to userspace when a performance domain is created or deleted, or its energy model is updated. Signed-off-by: Changwoo Min Reviewed-by: Lukasz Luba Link: https://patch.msgid.link/20251020220914.320832-11-changwoo@igalia.com Signed-off-by: Rafael J. Wysocki

PM: EM: Add an iterator and accessor for the performance domain

2025-10-22T19:44:37Z

Add an iterator function (for_each_em_perf_domain) that iterates all the performance domains in the global list. A passed callback function (cb) is called for each performance domain. Additionally, add a lookup function (em_perf_domain_get_by_id) that searches for a performance domain by matching the ID in the global list. Signed-off-by: Changwoo Min Reviewed-by: Lukasz Luba Link: https://patch.msgid.link/20251020220914.320832-6-changwoo@igalia.com Signed-off-by: Rafael J. Wysocki

PM: EM: Expose the ID of a performance domain via debugfs

2025-10-22T19:44:37Z

For ease of debugging, let's expose the assigned ID of a performance domain through debugfs (e.g., /sys/kernel/debug/energy_model/cpu0/id). Signed-off-by: Changwoo Min Reviewed-by: Lukasz Luba Link: https://patch.msgid.link/20251020220914.320832-3-changwoo@igalia.com Signed-off-by: Rafael J. Wysocki

PM: EM: Assign a unique ID when creating a performance domain

2025-10-22T19:44:37Z

It is necessary to refer to a specific performance domain from a userspace. For example, the energy model of a particular performance domain is updated. To this end, assign a unique ID to each performance domain to address it, and manage them in a global linked list to look up a specific one by matching ID. IDA is used for ID assignment, and the mutex is used to protect the global list from concurrent access. Note that the mutex (em_pd_list_mutex) is not supposed to hold while holding em_pd_mutex to avoid ABBA deadlock. Signed-off-by: Changwoo Min Reviewed-by: Lukasz Luba Link: https://patch.msgid.link/20251020220914.320832-2-changwoo@igalia.com Signed-off-by: Rafael J. Wysocki

PM: EM: Fix late boot with holes in CPU topology

2025-09-15T10:02:24Z

Commit e3f1164fc9ee ("PM: EM: Support late CPUs booting and capacity adjustment") added a mechanism to handle CPUs that come up late by retrying when any of the `cpufreq_cpu_get()` call fails. However, if there are holes in the CPU topology (offline CPUs, e.g. nosmt), the first missing CPU causes the loop to break, preventing subsequent online CPUs from being updated. Instead of aborting on the first missing CPU policy, loop through all and retry if any were missing. Fixes: e3f1164fc9ee ("PM: EM: Support late CPUs booting and capacity adjustment") Suggested-by: Kenneth Crudup Reported-by: Kenneth Crudup Link: https://lore.kernel.org/linux-pm/40212796-734c-4140-8a85-854f72b8144d@panix.com/ Cc: 6.9+ # 6.9+ Signed-off-by: Christian Loehle Link: https://patch.msgid.link/20250831214357.2020076-1-christian.loehle@arm.com [ rjw: Drop the new pr_debug() message which is not very useful ] Signed-off-by: Rafael J. Wysocki

PM: EM: Add function for registering a PD without capacity update

2025-09-10T10:03:19Z

The intel_pstate driver manages CPU capacity changes itself and it does not need an update of the capacity of all CPUs in the system to be carried out after registering a PD. Moreover, in some configurations (for instance, an SMT-capable hybrid x86 system booted with nosmt in the kernel command line) the em_check_capacity_update() call at the end of em_dev_register_perf_domain() always fails and reschedules itself to run once again in 1 s, so effectively it runs in vain every 1 s forever. To address this, introduce a new variant of em_dev_register_perf_domain(), called em_dev_register_pd_no_update(), that does not invoke em_check_capacity_update(), and make intel_pstate use it instead of the original. Fixes: 7b010f9b9061 ("cpufreq: intel_pstate: EAS support for hybrid platforms") Closes: https://lore.kernel.org/linux-pm/40212796-734c-4140-8a85-854f72b8144d@panix.com/ Reported-by: Kenneth R. Crudup Tested-by: Kenneth R. Crudup Cc: 6.16+ # 6.16+ Signed-off-by: Rafael J. Wysocki

PM: EM: Introduce em_adjust_cpu_capacity()

2025-05-13T12:34:18Z

Add a function for updating the Energy Model for a CPU after its capacity has changed, which subsequently will be used by the intel_pstate driver. An EM_PERF_DOMAIN_ARTIFICIAL check is added to em_recalc_and_update() to prevent it from calling em_compute_costs() for an "artificial" perf domain with a NULL cb parameter which would cause it to crash. Signed-off-by: Rafael J. Wysocki Reviewed-by: Lukasz Luba Tested-by: Christian Loehle Reviewed-by: Dietmar Eggemann Link: https://patch.msgid.link/3637203.iIbC2pHGDl@rjwysocki.net

PM: EM: Move CPU capacity check to em_adjust_new_capacity()

2025-05-13T12:34:18Z

Move the check of the CPU capacity currently stored in the energy model against the arch_scale_cpu_capacity() value to em_adjust_new_capacity() so it will be done regardless of where the latter is called from. This will be useful when a new em_adjust_new_capacity() caller is added subsequently. While at it, move the pd local variable declaration in em_check_capacity_update() into the loop in which it is used. No intentional functional impact. Signed-off-by: Rafael J. Wysocki Reviewed-by: Lukasz Luba Tested-by: Christian Loehle Reviewed-by: Dietmar Eggemann Link: https://patch.msgid.link/7810787.EvYhyI6sBW@rjwysocki.net