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/e3x0-button.c | 135 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 135 insertions(+) create mode 100644 drivers/input/misc/e3x0-button.c (limited to 'drivers/input/misc/e3x0-button.c') diff --git a/drivers/input/misc/e3x0-button.c b/drivers/input/misc/e3x0-button.c new file mode 100644 index 000000000..5bd527117 --- /dev/null +++ b/drivers/input/misc/e3x0-button.c @@ -0,0 +1,135 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2014, National Instruments Corp. All rights reserved. + * + * Driver for NI Ettus Research USRP E3x0 Button Driver + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +static irqreturn_t e3x0_button_release_handler(int irq, void *data) +{ + struct input_dev *idev = data; + + input_report_key(idev, KEY_POWER, 0); + input_sync(idev); + + return IRQ_HANDLED; +} + +static irqreturn_t e3x0_button_press_handler(int irq, void *data) +{ + struct input_dev *idev = data; + + input_report_key(idev, KEY_POWER, 1); + pm_wakeup_event(idev->dev.parent, 0); + input_sync(idev); + + return IRQ_HANDLED; +} + +static int e3x0_button_suspend(struct device *dev) +{ + struct platform_device *pdev = to_platform_device(dev); + + if (device_may_wakeup(dev)) + enable_irq_wake(platform_get_irq_byname(pdev, "press")); + + return 0; +} + +static int e3x0_button_resume(struct device *dev) +{ + struct platform_device *pdev = to_platform_device(dev); + + if (device_may_wakeup(dev)) + disable_irq_wake(platform_get_irq_byname(pdev, "press")); + + return 0; +} + +static DEFINE_SIMPLE_DEV_PM_OPS(e3x0_button_pm_ops, + e3x0_button_suspend, e3x0_button_resume); + +static int e3x0_button_probe(struct platform_device *pdev) +{ + struct input_dev *input; + int irq_press, irq_release; + int error; + + irq_press = platform_get_irq_byname(pdev, "press"); + if (irq_press < 0) + return irq_press; + + irq_release = platform_get_irq_byname(pdev, "release"); + if (irq_release < 0) + return irq_release; + + input = devm_input_allocate_device(&pdev->dev); + if (!input) + return -ENOMEM; + + input->name = "NI Ettus Research USRP E3x0 Button Driver"; + input->phys = "e3x0_button/input0"; + input->dev.parent = &pdev->dev; + + input_set_capability(input, EV_KEY, KEY_POWER); + + error = devm_request_irq(&pdev->dev, irq_press, + e3x0_button_press_handler, 0, + "e3x0-button", input); + if (error) { + dev_err(&pdev->dev, "Failed to request 'press' IRQ#%d: %d\n", + irq_press, error); + return error; + } + + error = devm_request_irq(&pdev->dev, irq_release, + e3x0_button_release_handler, 0, + "e3x0-button", input); + if (error) { + dev_err(&pdev->dev, "Failed to request 'release' IRQ#%d: %d\n", + irq_release, error); + return error; + } + + error = input_register_device(input); + if (error) { + dev_err(&pdev->dev, "Can't register input device: %d\n", error); + return error; + } + + device_init_wakeup(&pdev->dev, 1); + return 0; +} + +#ifdef CONFIG_OF +static const struct of_device_id e3x0_button_match[] = { + { .compatible = "ettus,e3x0-button", }, + { } +}; +MODULE_DEVICE_TABLE(of, e3x0_button_match); +#endif + +static struct platform_driver e3x0_button_driver = { + .driver = { + .name = "e3x0-button", + .of_match_table = of_match_ptr(e3x0_button_match), + .pm = pm_sleep_ptr(&e3x0_button_pm_ops), + }, + .probe = e3x0_button_probe, +}; + +module_platform_driver(e3x0_button_driver); + +MODULE_LICENSE("GPL v2"); +MODULE_AUTHOR("Moritz Fischer "); +MODULE_DESCRIPTION("NI Ettus Research USRP E3x0 Button driver"); +MODULE_ALIAS("platform:e3x0-button"); -- cgit v1.3.1