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/mouse/rpcmouse.c | 113 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 113 insertions(+) create mode 100644 drivers/input/mouse/rpcmouse.c (limited to 'drivers/input/mouse/rpcmouse.c') diff --git a/drivers/input/mouse/rpcmouse.c b/drivers/input/mouse/rpcmouse.c new file mode 100644 index 000000000..6774029e0 --- /dev/null +++ b/drivers/input/mouse/rpcmouse.c @@ -0,0 +1,113 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Acorn RiscPC mouse driver for Linux/ARM + * + * Copyright (c) 2000-2002 Vojtech Pavlik + * Copyright (C) 1996-2002 Russell King + */ + +/* + * + * This handles the Acorn RiscPCs mouse. We basically have a couple of + * hardware registers that track the sensor count for the X-Y movement and + * another register holding the button state. On every VSYNC interrupt we read + * the complete state and then work out if something has changed. + */ + +#include +#include +#include +#include +#include +#include + +#include +#include +#include + +MODULE_AUTHOR("Vojtech Pavlik, Russell King"); +MODULE_DESCRIPTION("Acorn RiscPC mouse driver"); +MODULE_LICENSE("GPL"); + +static short rpcmouse_lastx, rpcmouse_lasty; +static struct input_dev *rpcmouse_dev; + +static irqreturn_t rpcmouse_irq(int irq, void *dev_id) +{ + struct input_dev *dev = dev_id; + short x, y, dx, dy, b; + + x = (short) iomd_readl(IOMD_MOUSEX); + y = (short) iomd_readl(IOMD_MOUSEY); + b = (short) (__raw_readl(IOMEM(0xe0310000)) ^ 0x70); + + dx = x - rpcmouse_lastx; + dy = y - rpcmouse_lasty; + + rpcmouse_lastx = x; + rpcmouse_lasty = y; + + input_report_rel(dev, REL_X, dx); + input_report_rel(dev, REL_Y, -dy); + + input_report_key(dev, BTN_LEFT, b & 0x40); + input_report_key(dev, BTN_MIDDLE, b & 0x20); + input_report_key(dev, BTN_RIGHT, b & 0x10); + + input_sync(dev); + + return IRQ_HANDLED; +} + + +static int __init rpcmouse_init(void) +{ + int err; + + rpcmouse_dev = input_allocate_device(); + if (!rpcmouse_dev) + return -ENOMEM; + + rpcmouse_dev->name = "Acorn RiscPC Mouse"; + rpcmouse_dev->phys = "rpcmouse/input0"; + rpcmouse_dev->id.bustype = BUS_HOST; + rpcmouse_dev->id.vendor = 0x0005; + rpcmouse_dev->id.product = 0x0001; + rpcmouse_dev->id.version = 0x0100; + + rpcmouse_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REL); + rpcmouse_dev->keybit[BIT_WORD(BTN_LEFT)] = BIT_MASK(BTN_LEFT) | + BIT_MASK(BTN_MIDDLE) | BIT_MASK(BTN_RIGHT); + rpcmouse_dev->relbit[0] = BIT_MASK(REL_X) | BIT_MASK(REL_Y); + + rpcmouse_lastx = (short) iomd_readl(IOMD_MOUSEX); + rpcmouse_lasty = (short) iomd_readl(IOMD_MOUSEY); + + if (request_irq(IRQ_VSYNCPULSE, rpcmouse_irq, IRQF_SHARED, "rpcmouse", rpcmouse_dev)) { + printk(KERN_ERR "rpcmouse: unable to allocate VSYNC interrupt\n"); + err = -EBUSY; + goto err_free_dev; + } + + err = input_register_device(rpcmouse_dev); + if (err) + goto err_free_irq; + + return 0; + + err_free_irq: + free_irq(IRQ_VSYNCPULSE, rpcmouse_dev); + err_free_dev: + input_free_device(rpcmouse_dev); + + return err; +} + +static void __exit rpcmouse_exit(void) +{ + free_irq(IRQ_VSYNCPULSE, rpcmouse_dev); + input_unregister_device(rpcmouse_dev); +} + +module_init(rpcmouse_init); +module_exit(rpcmouse_exit); -- cgit v1.3.1