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, 116 insertions, 0 deletions

diff --git a/include/sound/jack.h b/include/sound/jack.h
new file mode 100644
index 000000000..715b95983
--- /dev/null
+++ b/include/sound/jack.h
@@ -0,0 +1,116 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef __SOUND_JACK_H
+#define __SOUND_JACK_H
+
+/*
+ *  Jack abstraction layer
+ *
+ *  Copyright 2008 Wolfson Microelectronics plc
+ */
+
+#include <sound/core.h>
+
+struct input_dev;
+
+/**
+ * enum snd_jack_types - Jack types which can be reported
+ * @SND_JACK_HEADPHONE: Headphone
+ * @SND_JACK_MICROPHONE: Microphone
+ * @SND_JACK_HEADSET: Headset
+ * @SND_JACK_LINEOUT: Line out
+ * @SND_JACK_MECHANICAL: Mechanical switch
+ * @SND_JACK_VIDEOOUT: Video out
+ * @SND_JACK_AVOUT: AV (Audio Video) out
+ * @SND_JACK_LINEIN:  Line in
+ * @SND_JACK_USB: USB audio device
+ * @SND_JACK_BTN_0: Button 0
+ * @SND_JACK_BTN_1: Button 1
+ * @SND_JACK_BTN_2: Button 2
+ * @SND_JACK_BTN_3: Button 3
+ * @SND_JACK_BTN_4: Button 4
+ * @SND_JACK_BTN_5: Button 5
+ *
+ * These values are used as a bitmask.
+ *
+ * Note that this must be kept in sync with the lookup table in
+ * sound/core/jack.c.
+ */
+enum snd_jack_types {
+	SND_JACK_HEADPHONE	= 0x0001,
+	SND_JACK_MICROPHONE	= 0x0002,
+	SND_JACK_HEADSET	= SND_JACK_HEADPHONE | SND_JACK_MICROPHONE,
+	SND_JACK_LINEOUT	= 0x0004,
+	SND_JACK_MECHANICAL	= 0x0008, /* If detected separately */
+	SND_JACK_VIDEOOUT	= 0x0010,
+	SND_JACK_AVOUT		= SND_JACK_LINEOUT | SND_JACK_VIDEOOUT,
+	SND_JACK_LINEIN		= 0x0020,
+	SND_JACK_USB		= 0x0040,
+
+	/* Kept separate from switches to facilitate implementation */
+	SND_JACK_BTN_0		= 0x4000,
+	SND_JACK_BTN_1		= 0x2000,
+	SND_JACK_BTN_2		= 0x1000,
+	SND_JACK_BTN_3		= 0x0800,
+	SND_JACK_BTN_4		= 0x0400,
+	SND_JACK_BTN_5		= 0x0200,
+};
+
+/* Keep in sync with definitions above */
+#define SND_JACK_SWITCH_TYPES 7
+
+struct snd_jack {
+	struct list_head kctl_list;
+	struct snd_card *card;
+	const char *id;
+#ifdef CONFIG_SND_JACK_INPUT_DEV
+	struct input_dev *input_dev;
+	struct mutex input_dev_lock;
+	int registered;
+	int type;
+	char name[100];
+	unsigned int key[6];   /* Keep in sync with definitions above */
+#endif /* CONFIG_SND_JACK_INPUT_DEV */
+	int hw_status_cache;
+	void *private_data;
+	void (*private_free)(struct snd_jack *);
+};
+
+#ifdef CONFIG_SND_JACK
+
+int snd_jack_new(struct snd_card *card, const char *id, int type,
+		 struct snd_jack **jack, bool initial_kctl, bool phantom_jack);
+int snd_jack_add_new_kctl(struct snd_jack *jack, const char * name, int mask);
+#ifdef CONFIG_SND_JACK_INPUT_DEV
+int snd_jack_set_key(struct snd_jack *jack, enum snd_jack_types type,
+		     int keytype);
+#endif
+void snd_jack_report(struct snd_jack *jack, int status);
+
+#else
+static inline int snd_jack_new(struct snd_card *card, const char *id, int type,
+			       struct snd_jack **jack, bool initial_kctl, bool phantom_jack)
+{
+	return 0;
+}
+
+static inline int snd_jack_add_new_kctl(struct snd_jack *jack, const char * name, int mask)
+{
+	return 0;
+}
+
+static inline void snd_jack_report(struct snd_jack *jack, int status)
+{
+}
+
+#endif
+
+#if !defined(CONFIG_SND_JACK) || !defined(CONFIG_SND_JACK_INPUT_DEV)
+static inline int snd_jack_set_key(struct snd_jack *jack,
+				   enum snd_jack_types type,
+				   int keytype)
+{
+	return 0;
+}
+#endif /* !CONFIG_SND_JACK || !CONFIG_SND_JACK_INPUT_DEV */
+
+#endif