From 0d6526f82c3cdefcca47f73f5fc08dc6f335eac6 Mon Sep 17 00:00:00 2001 From: Tim Chen Date: Mon, 21 Sep 2026 17:37:22 -0700 Subject: sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling bug alb_break_llc() decides whether to break LLC preference during active load balance. It does so by testing that every runnable fair task on the source rq prefers its LLC: env->src_rq->nr_pref_llc_running == env->src_rq->cfs.h_nr_runnable But the two counters cover different sets. nr_pref_llc_running is updated in account_llc_enqueue()/account_llc_dequeue(), next to cfs_rq->nr_queued, so it follows queued tasks. h_nr_runnable is updated in set_delayed()/ clear_delayed() and drops delay-dequeued tasks. So under DELAY_DEQUEUE, a preferring task that goes to sleep stays counted in nr_pref_llc_running while h_nr_runnable falls. The equality then breaks, alb_break_llc() returns false, and active balance is free to pull a task off its preferred LLC. Active balance only moves runnable tasks, and this is the only LLC check it consults: once the stopper runs, LBF_ACTIVE_LB skips the per-task test in can_migrate_task(). The runnable set is the one we want. Fix it on the counter side. A task should be counted in nr_pref_llc_running exactly while it is both queued on its preferred LLC (pref_llc_queued) and runnable (!sched_delayed). Define that membership once in task_pref_llc_runnable(), and adjust the counter only through pref_llc_running_inc()/pref_llc_running_dec() from the four sites that change either input: account_llc_enqueue(), account_llc_dequeue(), set_delayed() and clear_delayed(). Gating every update on the same predicate keeps the delay, wake and dequeue paths from double-counting or underflowing; see the comments at those sites for the ordering. nr_llc_running and sd->llc_counts are not touched and stay on queued semantics. Fixes: 714059f79ff0 ("sched/cache: Handle moving single tasks to/from their preferred LLC") Closes: https://lore.kernel.org/lkml/20260827135000.735138-1-zhanxusheng@xiaomi.com/ Reported-by: Zhan Xusheng Suggested-by: Chen Yu Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Kayra Cizmeci Cc: # v7.2.x Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com --- drivers/acpi/thermal_lib.c | 166 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 166 insertions(+) create mode 100644 drivers/acpi/thermal_lib.c (limited to 'drivers/acpi/thermal_lib.c') diff --git a/drivers/acpi/thermal_lib.c b/drivers/acpi/thermal_lib.c new file mode 100644 index 000000000..f81591927 --- /dev/null +++ b/drivers/acpi/thermal_lib.c @@ -0,0 +1,166 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright 2023 Linaro Limited + * Copyright 2023 Intel Corporation + * + * Library routines for retrieving trip point temperature values from the + * platform firmware via ACPI. + */ +#include +#include +#include +#include "internal.h" + +/* + * Minimum temperature for full military grade is 218°K (-55°C) and + * max temperature is 448°K (175°C). We can consider those values as + * the boundaries for the [trips] temperature returned by the + * firmware. Any values out of these boundaries may be considered + * bogus and we can assume the firmware has no data to provide. + */ +#define TEMP_MIN_DECIK 2180ULL +#define TEMP_MAX_DECIK 4480ULL + +static int acpi_trip_temp(struct acpi_device *adev, char *obj_name, + int *ret_temp) +{ + unsigned long long temp; + acpi_status status; + + status = acpi_evaluate_integer(adev->handle, obj_name, NULL, &temp); + if (ACPI_FAILURE(status)) { + acpi_handle_debug(adev->handle, "%s evaluation failed\n", obj_name); + return -ENODATA; + } + + if (temp >= TEMP_MIN_DECIK && temp <= TEMP_MAX_DECIK) { + *ret_temp = temp; + } else { + acpi_handle_debug(adev->handle, "%s result %llu out of range\n", + obj_name, temp); + *ret_temp = THERMAL_TEMP_INVALID; + } + + return 0; +} + +int acpi_active_trip_temp(struct acpi_device *adev, int id, int *ret_temp) +{ + char obj_name[] = {'_', 'A', 'C', '0' + id, '\0'}; + + if (id < 0 || id > 9) + return -EINVAL; + + return acpi_trip_temp(adev, obj_name, ret_temp); +} +EXPORT_SYMBOL_NS_GPL(acpi_active_trip_temp, "ACPI_THERMAL"); + +int acpi_passive_trip_temp(struct acpi_device *adev, int *ret_temp) +{ + return acpi_trip_temp(adev, "_PSV", ret_temp); +} +EXPORT_SYMBOL_NS_GPL(acpi_passive_trip_temp, "ACPI_THERMAL"); + +int acpi_hot_trip_temp(struct acpi_device *adev, int *ret_temp) +{ + return acpi_trip_temp(adev, "_HOT", ret_temp); +} +EXPORT_SYMBOL_NS_GPL(acpi_hot_trip_temp, "ACPI_THERMAL"); + +int acpi_critical_trip_temp(struct acpi_device *adev, int *ret_temp) +{ + return acpi_trip_temp(adev, "_CRT", ret_temp); +} +EXPORT_SYMBOL_NS_GPL(acpi_critical_trip_temp, "ACPI_THERMAL"); + +static int thermal_temp(int error, int temp_decik, int *ret_temp) +{ + if (error) + return error; + + if (temp_decik == THERMAL_TEMP_INVALID) + *ret_temp = THERMAL_TEMP_INVALID; + else + *ret_temp = deci_kelvin_to_millicelsius(temp_decik); + + return 0; +} + +/** + * thermal_acpi_active_trip_temp - Retrieve active trip point temperature + * @adev: Target thermal zone ACPI device object. + * @id: Active cooling level (0 - 9). + * @ret_temp: Address to store the retrieved temperature value on success. + * + * Evaluate the _ACx object for the thermal zone represented by @adev to obtain + * the temperature of the active cooling trip point corresponding to the active + * cooling level given by @id. + * + * Return 0 on success or a negative error value on failure. + */ +int thermal_acpi_active_trip_temp(struct acpi_device *adev, int id, int *ret_temp) +{ + int temp_decik = 0; + int ret = acpi_active_trip_temp(adev, id, &temp_decik); + + return thermal_temp(ret, temp_decik, ret_temp); +} +EXPORT_SYMBOL_GPL(thermal_acpi_active_trip_temp); + +/** + * thermal_acpi_passive_trip_temp - Retrieve passive trip point temperature + * @adev: Target thermal zone ACPI device object. + * @ret_temp: Address to store the retrieved temperature value on success. + * + * Evaluate the _PSV object for the thermal zone represented by @adev to obtain + * the temperature of the passive cooling trip point. + * + * Return 0 on success or -ENODATA on failure. + */ +int thermal_acpi_passive_trip_temp(struct acpi_device *adev, int *ret_temp) +{ + int temp_decik = 0; + int ret = acpi_passive_trip_temp(adev, &temp_decik); + + return thermal_temp(ret, temp_decik, ret_temp); +} +EXPORT_SYMBOL_GPL(thermal_acpi_passive_trip_temp); + +/** + * thermal_acpi_hot_trip_temp - Retrieve hot trip point temperature + * @adev: Target thermal zone ACPI device object. + * @ret_temp: Address to store the retrieved temperature value on success. + * + * Evaluate the _HOT object for the thermal zone represented by @adev to obtain + * the temperature of the trip point at which the system is expected to be put + * into the S4 sleep state. + * + * Return 0 on success or -ENODATA on failure. + */ +int thermal_acpi_hot_trip_temp(struct acpi_device *adev, int *ret_temp) +{ + int temp_decik = 0; + int ret = acpi_hot_trip_temp(adev, &temp_decik); + + return thermal_temp(ret, temp_decik, ret_temp); +} +EXPORT_SYMBOL_GPL(thermal_acpi_hot_trip_temp); + +/** + * thermal_acpi_critical_trip_temp - Retrieve critical trip point temperature + * @adev: Target thermal zone ACPI device object. + * @ret_temp: Address to store the retrieved temperature value on success. + * + * Evaluate the _CRT object for the thermal zone represented by @adev to obtain + * the temperature of the critical cooling trip point. + * + * Return 0 on success or -ENODATA on failure. + */ +int thermal_acpi_critical_trip_temp(struct acpi_device *adev, int *ret_temp) +{ + int temp_decik = 0; + int ret = acpi_critical_trip_temp(adev, &temp_decik); + + return thermal_temp(ret, temp_decik, ret_temp); +} +EXPORT_SYMBOL_GPL(thermal_acpi_critical_trip_temp); -- cgit v1.3.1