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/serio/maceps2.c | 204 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 204 insertions(+) create mode 100644 drivers/input/serio/maceps2.c (limited to 'drivers/input/serio/maceps2.c') diff --git a/drivers/input/serio/maceps2.c b/drivers/input/serio/maceps2.c new file mode 100644 index 000000000..fb41e7f5a --- /dev/null +++ b/drivers/input/serio/maceps2.c @@ -0,0 +1,204 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * SGI O2 MACE PS2 controller driver for linux + * + * Copyright (C) 2002 Vivien Chappelier + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include + +MODULE_AUTHOR("Vivien Chappelier port_data)->port; + unsigned int timeout = MACE_PS2_TIMEOUT; + + do { + if (port->status & PS2_STATUS_TX_EMPTY) { + port->tx = val; + return 0; + } + udelay(50); + } while (timeout--); + + return -1; +} + +static irqreturn_t maceps2_interrupt(int irq, void *dev_id) +{ + struct serio *dev = dev_id; + struct mace_ps2port *port = ((struct maceps2_data *)dev->port_data)->port; + unsigned long byte; + + if (port->status & PS2_STATUS_RX_FULL) { + byte = port->rx; + serio_interrupt(dev, byte & 0xff, 0); + } + + return IRQ_HANDLED; +} + +static int maceps2_open(struct serio *dev) +{ + struct maceps2_data *data = (struct maceps2_data *)dev->port_data; + + if (request_irq(data->irq, maceps2_interrupt, 0, "PS2 port", dev)) { + printk(KERN_ERR "Could not allocate PS/2 IRQ\n"); + return -EBUSY; + } + + /* Reset port */ + data->port->control = PS2_CONTROL_TX_CLOCK_DISABLE | PS2_CONTROL_RESET; + udelay(100); + + /* Enable interrupts */ + data->port->control = PS2_CONTROL_RX_CLOCK_ENABLE | + PS2_CONTROL_TX_ENABLE | + PS2_CONTROL_RX_INT_ENABLE; + + return 0; +} + +static void maceps2_close(struct serio *dev) +{ + struct maceps2_data *data = (struct maceps2_data *)dev->port_data; + + data->port->control = PS2_CONTROL_TX_CLOCK_DISABLE | PS2_CONTROL_RESET; + udelay(100); + free_irq(data->irq, dev); +} + + +static struct serio *maceps2_allocate_port(int idx) +{ + struct serio *serio; + + serio = kzalloc_obj(*serio); + if (serio) { + serio->id.type = SERIO_8042; + serio->write = maceps2_write; + serio->open = maceps2_open; + serio->close = maceps2_close; + snprintf(serio->name, sizeof(serio->name), "MACE PS/2 port%d", idx); + snprintf(serio->phys, sizeof(serio->phys), "mace/serio%d", idx); + serio->port_data = &port_data[idx]; + serio->dev.parent = &maceps2_device->dev; + } + + return serio; +} + +static int maceps2_probe(struct platform_device *dev) +{ + maceps2_port[0] = maceps2_allocate_port(0); + maceps2_port[1] = maceps2_allocate_port(1); + if (!maceps2_port[0] || !maceps2_port[1]) { + kfree(maceps2_port[0]); + kfree(maceps2_port[1]); + return -ENOMEM; + } + + serio_register_port(maceps2_port[0]); + serio_register_port(maceps2_port[1]); + + return 0; +} + +static void maceps2_remove(struct platform_device *dev) +{ + serio_unregister_port(maceps2_port[0]); + serio_unregister_port(maceps2_port[1]); +} + +static struct platform_driver maceps2_driver = { + .driver = { + .name = "maceps2", + }, + .probe = maceps2_probe, + .remove = maceps2_remove, +}; + +static int __init maceps2_init(void) +{ + int error; + + error = platform_driver_register(&maceps2_driver); + if (error) + return error; + + maceps2_device = platform_device_alloc("maceps2", -1); + if (!maceps2_device) { + error = -ENOMEM; + goto err_unregister_driver; + } + + port_data[0].port = &mace->perif.ps2.keyb; + port_data[0].irq = MACEISA_KEYB_IRQ; + port_data[1].port = &mace->perif.ps2.mouse; + port_data[1].irq = MACEISA_MOUSE_IRQ; + + error = platform_device_add(maceps2_device); + if (error) + goto err_free_device; + + return 0; + + err_free_device: + platform_device_put(maceps2_device); + err_unregister_driver: + platform_driver_unregister(&maceps2_driver); + return error; +} + +static void __exit maceps2_exit(void) +{ + platform_device_unregister(maceps2_device); + platform_driver_unregister(&maceps2_driver); +} + +module_init(maceps2_init); +module_exit(maceps2_exit); -- cgit v1.3.1