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/input/misc/cpcap-pwrbutton.c | 112 +++++++++++++++++++++++++++++++++++ 1 file changed, 112 insertions(+) create mode 100644 drivers/input/misc/cpcap-pwrbutton.c (limited to 'drivers/input/misc/cpcap-pwrbutton.c') diff --git a/drivers/input/misc/cpcap-pwrbutton.c b/drivers/input/misc/cpcap-pwrbutton.c new file mode 100644 index 000000000..85cddb847 --- /dev/null +++ b/drivers/input/misc/cpcap-pwrbutton.c @@ -0,0 +1,112 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * CPCAP Power Button Input Driver + * + * Copyright (C) 2017 Sebastian Reichel + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define CPCAP_IRQ_ON 23 +#define CPCAP_IRQ_ON_BITMASK (1 << (CPCAP_IRQ_ON % 16)) + +struct cpcap_power_button { + struct regmap *regmap; + struct input_dev *idev; + struct device *dev; +}; + +static irqreturn_t powerbutton_irq(int irq, void *_button) +{ + struct cpcap_power_button *button = _button; + int val; + + val = cpcap_sense_virq(button->regmap, irq); + if (val < 0) { + dev_err(button->dev, "irq read failed: %d", val); + return IRQ_HANDLED; + } + + pm_wakeup_event(button->dev, 0); + input_report_key(button->idev, KEY_POWER, val); + input_sync(button->idev); + + return IRQ_HANDLED; +} + +static int cpcap_power_button_probe(struct platform_device *pdev) +{ + struct cpcap_power_button *button; + int irq; + int err; + + irq = platform_get_irq(pdev, 0); + if (irq < 0) + return irq; + + button = devm_kmalloc(&pdev->dev, sizeof(*button), GFP_KERNEL); + if (!button) + return -ENOMEM; + + button->idev = devm_input_allocate_device(&pdev->dev); + if (!button->idev) + return -ENOMEM; + + button->regmap = dev_get_regmap(pdev->dev.parent, NULL); + if (!button->regmap) + return -ENODEV; + + button->dev = &pdev->dev; + + button->idev->name = "cpcap-pwrbutton"; + button->idev->phys = "cpcap-pwrbutton/input0"; + input_set_capability(button->idev, EV_KEY, KEY_POWER); + + err = devm_request_threaded_irq(&pdev->dev, irq, NULL, + powerbutton_irq, IRQF_ONESHOT, "cpcap_pwrbutton", button); + if (err < 0) { + dev_err(&pdev->dev, "IRQ request failed: %d\n", err); + return err; + } + + err = input_register_device(button->idev); + if (err) { + dev_err(&pdev->dev, "Input register failed: %d\n", err); + return err; + } + + device_init_wakeup(&pdev->dev, true); + + return 0; +} + +#ifdef CONFIG_OF +static const struct of_device_id cpcap_pwrbutton_dt_match_table[] = { + { .compatible = "motorola,cpcap-pwrbutton" }, + {}, +}; +MODULE_DEVICE_TABLE(of, cpcap_pwrbutton_dt_match_table); +#endif + +static struct platform_driver cpcap_power_button_driver = { + .probe = cpcap_power_button_probe, + .driver = { + .name = "cpcap-pwrbutton", + .of_match_table = of_match_ptr(cpcap_pwrbutton_dt_match_table), + }, +}; +module_platform_driver(cpcap_power_button_driver); + +MODULE_ALIAS("platform:cpcap-pwrbutton"); +MODULE_DESCRIPTION("CPCAP Power Button"); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Sebastian Reichel "); -- cgit v1.3.1