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/mfd/ab8500-sysctrl.c | 169 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 169 insertions(+) create mode 100644 drivers/mfd/ab8500-sysctrl.c (limited to 'drivers/mfd/ab8500-sysctrl.c') diff --git a/drivers/mfd/ab8500-sysctrl.c b/drivers/mfd/ab8500-sysctrl.c new file mode 100644 index 000000000..b6b44e2e3 --- /dev/null +++ b/drivers/mfd/ab8500-sysctrl.c @@ -0,0 +1,169 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * AB8500 system control driver + * + * Copyright (C) ST-Ericsson SA 2010 + * Author: Mattias Nilsson for ST Ericsson. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* RtcCtrl bits */ +#define AB8500_ALARM_MIN_LOW 0x08 +#define AB8500_ALARM_MIN_MID 0x09 +#define RTC_CTRL 0x0B +#define RTC_ALARM_ENABLE 0x4 + +static struct device *sysctrl_dev; + +static void ab8500_power_off(void) +{ + sigset_t old; + sigset_t all; + static const char * const pss[] = {"ab8500_ac", "ab8500_usb"}; + int i; + bool charger_present = false; + union power_supply_propval val; + struct power_supply *psy; + int ret; + + if (sysctrl_dev == NULL) { + pr_err("%s: sysctrl not initialized\n", __func__); + return; + } + + /* + * If we have a charger connected and we're powering off, + * reboot into charge-only mode. + */ + + for (i = 0; i < ARRAY_SIZE(pss); i++) { + psy = power_supply_get_by_name(pss[i]); + if (!psy) + continue; + + ret = power_supply_get_property(psy, POWER_SUPPLY_PROP_ONLINE, + &val); + power_supply_put(psy); + + if (!ret && val.intval) { + charger_present = true; + break; + } + } + + if (!charger_present) + goto shutdown; + + /* Check if battery is known */ + psy = power_supply_get_by_name("ab8500_btemp"); + if (psy) { + ret = power_supply_get_property(psy, + POWER_SUPPLY_PROP_TECHNOLOGY, &val); + if (!ret && val.intval != POWER_SUPPLY_TECHNOLOGY_UNKNOWN) { + pr_info("Charger '%s' is connected with known battery", + pss[i]); + pr_info(" - Rebooting.\n"); + machine_restart("charging"); + } + power_supply_put(psy); + } + +shutdown: + sigfillset(&all); + + if (!sigprocmask(SIG_BLOCK, &all, &old)) { + (void)ab8500_sysctrl_set(AB8500_STW4500CTRL1, + AB8500_STW4500CTRL1_SWOFF | + AB8500_STW4500CTRL1_SWRESET4500N); + (void)sigprocmask(SIG_SETMASK, &old, NULL); + } +} + +static inline bool valid_bank(u8 bank) +{ + return ((bank == AB8500_SYS_CTRL1_BLOCK) || + (bank == AB8500_SYS_CTRL2_BLOCK)); +} + +int ab8500_sysctrl_read(u16 reg, u8 *value) +{ + u8 bank; + + if (sysctrl_dev == NULL) + return -EPROBE_DEFER; + + bank = (reg >> 8); + if (!valid_bank(bank)) + return -EINVAL; + + return abx500_get_register_interruptible(sysctrl_dev, bank, + (u8)(reg & 0xFF), value); +} +EXPORT_SYMBOL(ab8500_sysctrl_read); + +int ab8500_sysctrl_write(u16 reg, u8 mask, u8 value) +{ + u8 bank; + + if (sysctrl_dev == NULL) + return -EPROBE_DEFER; + + bank = (reg >> 8); + if (!valid_bank(bank)) { + pr_err("invalid bank\n"); + return -EINVAL; + } + + return abx500_mask_and_set_register_interruptible(sysctrl_dev, bank, + (u8)(reg & 0xFF), mask, value); +} +EXPORT_SYMBOL(ab8500_sysctrl_write); + +static int ab8500_sysctrl_probe(struct platform_device *pdev) +{ + sysctrl_dev = &pdev->dev; + + if (!pm_power_off) + pm_power_off = ab8500_power_off; + + return 0; +} + +static void ab8500_sysctrl_remove(struct platform_device *pdev) +{ + sysctrl_dev = NULL; + + if (pm_power_off == ab8500_power_off) + pm_power_off = NULL; +} + +static const struct of_device_id ab8500_sysctrl_match[] = { + { .compatible = "stericsson,ab8500-sysctrl", }, + {} +}; + +static struct platform_driver ab8500_sysctrl_driver = { + .driver = { + .name = "ab8500-sysctrl", + .of_match_table = ab8500_sysctrl_match, + }, + .probe = ab8500_sysctrl_probe, + .remove = ab8500_sysctrl_remove, +}; + +static int __init ab8500_sysctrl_init(void) +{ + return platform_driver_register(&ab8500_sysctrl_driver); +} +arch_initcall(ab8500_sysctrl_init); -- cgit v1.3.1