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/joystick/joydump.c | 142 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 142 insertions(+) create mode 100644 drivers/input/joystick/joydump.c (limited to 'drivers/input/joystick/joydump.c') diff --git a/drivers/input/joystick/joydump.c b/drivers/input/joystick/joydump.c new file mode 100644 index 000000000..c9cbdcc7f --- /dev/null +++ b/drivers/input/joystick/joydump.c @@ -0,0 +1,142 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (c) 1996-2001 Vojtech Pavlik + */ + +/* + * This is just a very simple driver that can dump the data + * out of the joystick port into the syslog ... + */ + +#include +#include +#include +#include +#include + +#define DRIVER_DESC "Gameport data dumper module" + +MODULE_AUTHOR("Vojtech Pavlik "); +MODULE_DESCRIPTION(DRIVER_DESC); +MODULE_LICENSE("GPL"); + +#define BUF_SIZE 256 + +struct joydump { + unsigned int time; + unsigned char data; +}; + +static int joydump_connect(struct gameport *gameport, struct gameport_driver *drv) +{ + struct joydump *buf; /* all entries */ + struct joydump *dump, *prev; /* one entry each */ + int axes[4], buttons; + int i, j, t, timeout; + unsigned long flags; + unsigned char u; + + printk(KERN_INFO "joydump: ,------------------ START ----------------.\n"); + printk(KERN_INFO "joydump: | Dumping: %30s |\n", gameport->phys); + printk(KERN_INFO "joydump: | Speed: %28d kHz |\n", gameport->speed); + + if (gameport_open(gameport, drv, GAMEPORT_MODE_RAW)) { + + printk(KERN_INFO "joydump: | Raw mode not available - trying cooked. |\n"); + + if (gameport_open(gameport, drv, GAMEPORT_MODE_COOKED)) { + + printk(KERN_INFO "joydump: | Cooked not available either. Failing. |\n"); + printk(KERN_INFO "joydump: `------------------- END -----------------'\n"); + return -ENODEV; + } + + gameport_cooked_read(gameport, axes, &buttons); + + for (i = 0; i < 4; i++) + printk(KERN_INFO "joydump: | Axis %d: %4d. |\n", i, axes[i]); + printk(KERN_INFO "joydump: | Buttons %02x. |\n", buttons); + printk(KERN_INFO "joydump: `------------------- END -----------------'\n"); + } + + timeout = gameport_time(gameport, 10000); /* 10 ms */ + + buf = kmalloc_objs(struct joydump, BUF_SIZE); + if (!buf) { + printk(KERN_INFO "joydump: no memory for testing\n"); + goto jd_end; + } + dump = buf; + t = 0; + i = 1; + + local_irq_save(flags); + + u = gameport_read(gameport); + + dump->data = u; + dump->time = t; + dump++; + + gameport_trigger(gameport); + + while (i < BUF_SIZE && t < timeout) { + + dump->data = gameport_read(gameport); + + if (dump->data ^ u) { + u = dump->data; + dump->time = t; + i++; + dump++; + } + t++; + } + + local_irq_restore(flags); + +/* + * Dump data. + */ + + t = i; + dump = buf; + prev = dump; + + printk(KERN_INFO "joydump: >------------------ DATA -----------------<\n"); + printk(KERN_INFO "joydump: | index: %3d delta: %3d us data: ", 0, 0); + for (j = 7; j >= 0; j--) + printk("%d", (dump->data >> j) & 1); + printk(" |\n"); + dump++; + + for (i = 1; i < t; i++, dump++, prev++) { + printk(KERN_INFO "joydump: | index: %3d delta: %3d us data: ", + i, dump->time - prev->time); + for (j = 7; j >= 0; j--) + printk("%d", (dump->data >> j) & 1); + printk(" |\n"); + } + kfree(buf); + +jd_end: + printk(KERN_INFO "joydump: `------------------- END -----------------'\n"); + + return 0; +} + +static void joydump_disconnect(struct gameport *gameport) +{ + gameport_close(gameport); +} + +static struct gameport_driver joydump_drv = { + .driver = { + .name = "joydump", + }, + .description = DRIVER_DESC, + .connect = joydump_connect, + .disconnect = joydump_disconnect, +}; + +module_gameport_driver(joydump_drv); -- cgit v1.3.1