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/hid/hid-cherry.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 72 insertions(+) create mode 100644 drivers/hid/hid-cherry.c (limited to 'drivers/hid/hid-cherry.c') diff --git a/drivers/hid/hid-cherry.c b/drivers/hid/hid-cherry.c new file mode 100644 index 000000000..a504632fe --- /dev/null +++ b/drivers/hid/hid-cherry.c @@ -0,0 +1,72 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * HID driver for some cherry "special" devices + * + * Copyright (c) 1999 Andreas Gal + * Copyright (c) 2000-2005 Vojtech Pavlik + * Copyright (c) 2005 Michael Haboustak for Concept2, Inc + * Copyright (c) 2006-2007 Jiri Kosina + * Copyright (c) 2008 Jiri Slaby + */ + +/* + */ + +#include +#include +#include + +#include "hid-ids.h" + +/* + * Cherry Cymotion keyboard have an invalid HID report descriptor, + * that needs fixing before we can parse it. + */ +static const __u8 *ch_report_fixup(struct hid_device *hdev, __u8 *rdesc, + unsigned int *rsize) +{ + if (*rsize >= 18 && rdesc[11] == 0x3c && rdesc[12] == 0x02) { + hid_info(hdev, "fixing up Cherry Cymotion report descriptor\n"); + rdesc[11] = rdesc[16] = 0xff; + rdesc[12] = rdesc[17] = 0x03; + } + return rdesc; +} + +#define ch_map_key_clear(c) hid_map_usage_clear(hi, usage, bit, max, \ + EV_KEY, (c)) +static int ch_input_mapping(struct hid_device *hdev, struct hid_input *hi, + struct hid_field *field, struct hid_usage *usage, + unsigned long **bit, int *max) +{ + if ((usage->hid & HID_USAGE_PAGE) != HID_UP_CONSUMER) + return 0; + + switch (usage->hid & HID_USAGE) { + case 0x301: ch_map_key_clear(KEY_PROG1); break; + case 0x302: ch_map_key_clear(KEY_PROG2); break; + case 0x303: ch_map_key_clear(KEY_PROG3); break; + default: + return 0; + } + + return 1; +} + +static const struct hid_device_id ch_devices[] = { + { HID_USB_DEVICE(USB_VENDOR_ID_CHERRY, USB_DEVICE_ID_CHERRY_CYMOTION) }, + { HID_USB_DEVICE(USB_VENDOR_ID_CHERRY, USB_DEVICE_ID_CHERRY_CYMOTION_SOLAR) }, + { } +}; +MODULE_DEVICE_TABLE(hid, ch_devices); + +static struct hid_driver ch_driver = { + .name = "cherry", + .id_table = ch_devices, + .report_fixup = ch_report_fixup, + .input_mapping = ch_input_mapping, +}; +module_hid_driver(ch_driver); + +MODULE_DESCRIPTION("HID driver for some cherry \"special\" devices"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1