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/pinctrl/pinctrl-utils.c | 129 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 129 insertions(+) create mode 100644 drivers/pinctrl/pinctrl-utils.c (limited to 'drivers/pinctrl/pinctrl-utils.c') diff --git a/drivers/pinctrl/pinctrl-utils.c b/drivers/pinctrl/pinctrl-utils.c new file mode 100644 index 000000000..b880e44b8 --- /dev/null +++ b/drivers/pinctrl/pinctrl-utils.c @@ -0,0 +1,129 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Utils functions to implement the pincontrol driver. + * + * Copyright (c) 2013, NVIDIA Corporation. + * + * Author: Laxman Dewangan + */ +#include +#include +#include +#include +#include + +#include + +#include "core.h" +#include "pinctrl-utils.h" + +int pinctrl_utils_reserve_map(struct pinctrl_dev *pctldev, + struct pinctrl_map **map, unsigned int *reserved_maps, + unsigned int *num_maps, unsigned int reserve) +{ + unsigned int old_num = *reserved_maps; + unsigned int new_num = *num_maps + reserve; + struct pinctrl_map *new_map; + + if (old_num >= new_num) + return 0; + + new_map = krealloc_array(*map, new_num, sizeof(*new_map), GFP_KERNEL); + if (!new_map) { + dev_err(pctldev->dev, "krealloc(map) failed\n"); + return -ENOMEM; + } + + memset(new_map + old_num, 0, (new_num - old_num) * sizeof(*new_map)); + + *map = new_map; + *reserved_maps = new_num; + return 0; +} +EXPORT_SYMBOL_GPL(pinctrl_utils_reserve_map); + +int pinctrl_utils_add_map_mux(struct pinctrl_dev *pctldev, + struct pinctrl_map **map, unsigned int *reserved_maps, + unsigned int *num_maps, const char *group, + const char *function) +{ + if (WARN_ON(*num_maps == *reserved_maps)) + return -ENOSPC; + + (*map)[*num_maps].type = PIN_MAP_TYPE_MUX_GROUP; + (*map)[*num_maps].data.mux.group = group; + (*map)[*num_maps].data.mux.function = function; + (*num_maps)++; + + return 0; +} +EXPORT_SYMBOL_GPL(pinctrl_utils_add_map_mux); + +int pinctrl_utils_add_map_configs(struct pinctrl_dev *pctldev, + struct pinctrl_map **map, unsigned int *reserved_maps, + unsigned int *num_maps, const char *group, + unsigned long *configs, unsigned int num_configs, + enum pinctrl_map_type type) +{ + unsigned long *dup_configs; + + if (WARN_ON(*num_maps == *reserved_maps)) + return -ENOSPC; + + dup_configs = kmemdup_array(configs, num_configs, + sizeof(*dup_configs), GFP_KERNEL); + if (!dup_configs) + return -ENOMEM; + + (*map)[*num_maps].type = type; + (*map)[*num_maps].data.configs.group_or_pin = group; + (*map)[*num_maps].data.configs.configs = dup_configs; + (*map)[*num_maps].data.configs.num_configs = num_configs; + (*num_maps)++; + + return 0; +} +EXPORT_SYMBOL_GPL(pinctrl_utils_add_map_configs); + +int pinctrl_utils_add_config(struct pinctrl_dev *pctldev, + unsigned long **configs, unsigned int *num_configs, + unsigned long config) +{ + unsigned int old_num = *num_configs; + unsigned int new_num = old_num + 1; + unsigned long *new_configs; + + new_configs = krealloc(*configs, sizeof(*new_configs) * new_num, + GFP_KERNEL); + if (!new_configs) { + dev_err(pctldev->dev, "krealloc(configs) failed\n"); + return -ENOMEM; + } + + new_configs[old_num] = config; + + *configs = new_configs; + *num_configs = new_num; + + return 0; +} +EXPORT_SYMBOL_GPL(pinctrl_utils_add_config); + +void pinctrl_utils_free_map(struct pinctrl_dev *pctldev, + struct pinctrl_map *map, unsigned int num_maps) +{ + int i; + + for (i = 0; i < num_maps; i++) { + switch (map[i].type) { + case PIN_MAP_TYPE_CONFIGS_GROUP: + case PIN_MAP_TYPE_CONFIGS_PIN: + kfree(map[i].data.configs.configs); + break; + default: + break; + } + } + kfree(map); +} +EXPORT_SYMBOL_GPL(pinctrl_utils_free_map); -- cgit v1.3.1