sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling buggrafted

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 <zhanxusheng@xiaomi.com>
Suggested-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kayra Cizmeci <kayracizmeci@gmail.com>
Cc: <stable@kernel.org> # v7.2.x
Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com

1 files changed, 135 insertions, 0 deletions

diff --git a/drivers/hid/hid-twinhan.c b/drivers/hid/hid-twinhan.c
new file mode 100644
index 000000000..0ef519408
--- /dev/null
+++ b/drivers/hid/hid-twinhan.c
@@ -0,0 +1,135 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * HID driver for TwinHan IR remote control
+ *
+ * Based on hid-gyration.c
+ *
+ * Copyright (c) 2009 Bruno Prémont <bonbons@linux-vserver.org>
+ */
+
+/*
+ */
+
+#include <linux/device.h>
+#include <linux/input.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+/*	Remote control key layout + listing:
+ *
+ * 	Full Screen                              Power
+ *	KEY_SCREEN                          KEY_POWER2
+ *
+ *	1                     2                      3
+ *	KEY_NUMERIC_1   KEY_NUMERIC_2    KEY_NUMERIC_3
+ *
+ *	4                     5                      6
+ *	KEY_NUMERIC_4   KEY_NUMERIC_5    KEY_NUMERIC_6
+ *
+ *	7                     8                      9
+ *	KEY_NUMERIC_7   KEY_NUMERIC_8    KEY_NUMERIC_9
+ *
+ *	REC                   0               Favorite
+ *	KEY_RECORD      KEY_NUMERIC_0    KEY_FAVORITES
+ *
+ *	Rewind                                 Forward
+ *	KEY_REWIND           CH+           KEY_FORWARD
+ *	               KEY_CHANNELUP
+ *
+ *	VOL-                  >                   VOL+
+ *	KEY_VOLUMEDOWN    KEY_PLAY        KEY_VOLUMEUP
+ *
+ *	                     CH-
+ *	              KEY_CHANNELDOWN
+ *	Recall                                    Stop
+ *	KEY_RESTART                           KEY_STOP
+ *
+ *	Timeshift/Pause     Mute                Cancel
+ *	KEY_PAUSE         KEY_MUTE          KEY_CANCEL
+ *
+ *	Capture            Preview                 EPG
+ *	KEY_PRINT        KEY_PROGRAM           KEY_EPG
+ *
+ *	Record List          Tab              Teletext
+ *	KEY_LIST            KEY_TAB           KEY_TEXT
+ */
+
+#define th_map_key_clear(c)	hid_map_usage_clear(hi, usage, bit, max, \
+					EV_KEY, (c))
+static int twinhan_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_KEYBOARD)
+		return 0;
+
+	switch (usage->hid & HID_USAGE) {
+	/* Map all keys from Twinhan Remote */
+	case 0x004: th_map_key_clear(KEY_TEXT);         break;
+	case 0x006: th_map_key_clear(KEY_RESTART);      break;
+	case 0x008: th_map_key_clear(KEY_EPG);          break;
+	case 0x00c: th_map_key_clear(KEY_REWIND);       break;
+	case 0x00e: th_map_key_clear(KEY_PROGRAM);      break;
+	case 0x00f: th_map_key_clear(KEY_LIST);         break;
+	case 0x010: th_map_key_clear(KEY_MUTE);         break;
+	case 0x011: th_map_key_clear(KEY_FORWARD);      break;
+	case 0x013: th_map_key_clear(KEY_PRINT);        break;
+	case 0x017: th_map_key_clear(KEY_PAUSE);        break;
+	case 0x019: th_map_key_clear(KEY_FAVORITES);    break;
+	case 0x01d: th_map_key_clear(KEY_SCREEN);       break;
+	case 0x01e: th_map_key_clear(KEY_NUMERIC_1);    break;
+	case 0x01f: th_map_key_clear(KEY_NUMERIC_2);    break;
+	case 0x020: th_map_key_clear(KEY_NUMERIC_3);    break;
+	case 0x021: th_map_key_clear(KEY_NUMERIC_4);    break;
+	case 0x022: th_map_key_clear(KEY_NUMERIC_5);    break;
+	case 0x023: th_map_key_clear(KEY_NUMERIC_6);    break;
+	case 0x024: th_map_key_clear(KEY_NUMERIC_7);    break;
+	case 0x025: th_map_key_clear(KEY_NUMERIC_8);    break;
+	case 0x026: th_map_key_clear(KEY_NUMERIC_9);    break;
+	case 0x027: th_map_key_clear(KEY_NUMERIC_0);    break;
+	case 0x028: th_map_key_clear(KEY_PLAY);         break;
+	case 0x029: th_map_key_clear(KEY_CANCEL);       break;
+	case 0x02b: th_map_key_clear(KEY_TAB);          break;
+	/* Power       = 0x0e0 + 0x0e1 + 0x0e2 + 0x03f */
+	case 0x03f: th_map_key_clear(KEY_POWER2);       break;
+	case 0x04a: th_map_key_clear(KEY_RECORD);       break;
+	case 0x04b: th_map_key_clear(KEY_CHANNELUP);    break;
+	case 0x04d: th_map_key_clear(KEY_STOP);         break;
+	case 0x04e: th_map_key_clear(KEY_CHANNELDOWN);  break;
+	/* Volume down = 0x0e1 + 0x051                 */
+	case 0x051: th_map_key_clear(KEY_VOLUMEDOWN);   break;
+	/* Volume up   = 0x0e1 + 0x052                 */
+	case 0x052: th_map_key_clear(KEY_VOLUMEUP);     break;
+	/* Kill the extra keys used for multi-key "power" and "volume" keys
+	 * as well as continuously to release CTRL,ALT,META,... keys */
+	case 0x0e0:
+	case 0x0e1:
+	case 0x0e2:
+	case 0x0e3:
+	case 0x0e4:
+	case 0x0e5:
+	case 0x0e6:
+	case 0x0e7:
+	default:
+		return -1;
+	}
+	return 1;
+}
+
+static const struct hid_device_id twinhan_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_TWINHAN, USB_DEVICE_ID_TWINHAN_IR_REMOTE) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, twinhan_devices);
+
+static struct hid_driver twinhan_driver = {
+	.name = "twinhan",
+	.id_table = twinhan_devices,
+	.input_mapping = twinhan_input_mapping,
+};
+module_hid_driver(twinhan_driver);
+
+MODULE_DESCRIPTION("HID driver for TwinHan IR remote control");
+MODULE_LICENSE("GPL");