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, 249 insertions, 0 deletions

diff --git a/drivers/input/mouse/psmouse.h b/drivers/input/mouse/psmouse.h
new file mode 100644
index 000000000..90ed8cd15
--- /dev/null
+++ b/drivers/input/mouse/psmouse.h
@@ -0,0 +1,249 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _PSMOUSE_H
+#define _PSMOUSE_H
+
+#define PSMOUSE_OOB_NONE	0x00
+#define PSMOUSE_OOB_EXTRA_BTNS	0x01
+
+#define PSMOUSE_CMD_SETSCALE11	0x00e6
+#define PSMOUSE_CMD_SETSCALE21	0x00e7
+#define PSMOUSE_CMD_SETRES	0x10e8
+#define PSMOUSE_CMD_GETINFO	0x03e9
+#define PSMOUSE_CMD_SETSTREAM	0x00ea
+#define PSMOUSE_CMD_SETPOLL	0x00f0
+#define PSMOUSE_CMD_POLL	0x00eb	/* caller sets number of bytes to receive */
+#define PSMOUSE_CMD_RESET_WRAP	0x00ec
+#define PSMOUSE_CMD_GETID	0x02f2
+#define PSMOUSE_CMD_SETRATE	0x10f3
+#define PSMOUSE_CMD_ENABLE	0x00f4
+#define PSMOUSE_CMD_DISABLE	0x00f5
+#define PSMOUSE_CMD_RESET_DIS	0x00f6
+#define PSMOUSE_CMD_RESET_BAT	0x02ff
+
+#define PSMOUSE_RET_BAT		0xaa
+#define PSMOUSE_RET_ID		0x00
+#define PSMOUSE_RET_ACK		0xfa
+#define PSMOUSE_RET_NAK		0xfe
+
+enum psmouse_state {
+	PSMOUSE_IGNORE,
+	PSMOUSE_INITIALIZING,
+	PSMOUSE_RESYNCING,
+	PSMOUSE_CMD_MODE,
+	PSMOUSE_ACTIVATED,
+};
+
+/* psmouse protocol handler return codes */
+typedef enum {
+	PSMOUSE_BAD_DATA,
+	PSMOUSE_GOOD_DATA,
+	PSMOUSE_FULL_PACKET
+} psmouse_ret_t;
+
+enum psmouse_scale {
+	PSMOUSE_SCALE11,
+	PSMOUSE_SCALE21
+};
+
+enum psmouse_type {
+	PSMOUSE_NONE,
+	PSMOUSE_PS2,
+	PSMOUSE_PS2PP,
+	PSMOUSE_THINKPS,
+	PSMOUSE_GENPS,
+	PSMOUSE_IMPS,
+	PSMOUSE_IMEX,
+	PSMOUSE_SYNAPTICS,
+	PSMOUSE_ALPS,
+	PSMOUSE_LIFEBOOK,
+	PSMOUSE_TRACKPOINT,
+	PSMOUSE_TOUCHKIT_PS2,
+	PSMOUSE_CORTRON,
+	PSMOUSE_HGPK,		/* No longer used */
+	PSMOUSE_ELANTECH,
+	PSMOUSE_FSP,
+	PSMOUSE_SYNAPTICS_RELATIVE,
+	PSMOUSE_CYPRESS,
+	PSMOUSE_FOCALTECH,
+	PSMOUSE_VMMOUSE,
+	PSMOUSE_BYD,
+	PSMOUSE_SYNAPTICS_SMBUS,
+	PSMOUSE_ELANTECH_SMBUS,
+	PSMOUSE_AUTO		/* This one should always be last */
+};
+
+struct psmouse;
+
+struct psmouse_protocol {
+	enum psmouse_type type;
+	bool maxproto;
+	bool ignore_parity; /* Protocol should ignore parity errors from KBC */
+	bool try_passthru; /* Try protocol also on passthrough ports */
+	bool smbus_companion; /* "Protocol" is a stub, device is on SMBus */
+	const char *name;
+	const char *alias;
+	int (*detect)(struct psmouse *, bool);
+	int (*init)(struct psmouse *);
+};
+
+struct psmouse {
+	void *private;
+	struct input_dev *dev;
+	struct ps2dev ps2dev;
+	struct work_struct resync_work;
+	const char *vendor;
+	const char *name;
+	const struct psmouse_protocol *protocol;
+	unsigned char packet[8];
+	unsigned char badbyte;
+	unsigned char pktcnt;
+	unsigned char pktsize;
+	unsigned char oob_data_type;
+	unsigned char extra_buttons;
+	bool acks_disable_command;
+	unsigned int model;
+	unsigned long last;
+	unsigned long out_of_sync_cnt;
+	unsigned long num_resyncs;
+	enum psmouse_state state;
+	char devname[64];
+	char phys[32];
+
+	unsigned int rate;
+	unsigned int resolution;
+	unsigned int resetafter;
+	unsigned int resync_time;
+	bool smartscroll;	/* Logitech only */
+
+	psmouse_ret_t (*protocol_handler)(struct psmouse *psmouse);
+	void (*set_rate)(struct psmouse *psmouse, unsigned int rate);
+	void (*set_resolution)(struct psmouse *psmouse, unsigned int resolution);
+	void (*set_scale)(struct psmouse *psmouse, enum psmouse_scale scale);
+
+	int (*reconnect)(struct psmouse *psmouse);
+	int (*fast_reconnect)(struct psmouse *psmouse);
+	void (*disconnect)(struct psmouse *psmouse);
+	void (*cleanup)(struct psmouse *psmouse);
+	int (*poll)(struct psmouse *psmouse);
+
+	void (*pt_activate)(struct psmouse *psmouse);
+	void (*pt_deactivate)(struct psmouse *psmouse);
+};
+
+struct psmouse *psmouse_from_serio(struct serio *serio);
+
+int psmouse_reset(struct psmouse *psmouse);
+void psmouse_set_state(struct psmouse *psmouse, enum psmouse_state new_state);
+void psmouse_set_resolution(struct psmouse *psmouse, unsigned int resolution);
+psmouse_ret_t psmouse_process_byte(struct psmouse *psmouse);
+int psmouse_activate(struct psmouse *psmouse);
+int psmouse_deactivate(struct psmouse *psmouse);
+bool psmouse_matches_pnp_id(struct psmouse *psmouse, const char * const ids[]);
+
+void psmouse_report_standard_buttons(struct input_dev *, u8 buttons);
+void psmouse_report_standard_motion(struct input_dev *, u8 *packet);
+void psmouse_report_standard_packet(struct input_dev *, u8 *packet);
+
+struct psmouse_attribute {
+	struct device_attribute dattr;
+	void *data;
+	ssize_t (*show)(struct psmouse *psmouse, void *data, char *buf);
+	ssize_t (*set)(struct psmouse *psmouse, void *data,
+			const char *buf, size_t count);
+	bool protect;
+};
+#define to_psmouse_attr(a)	container_of((a), struct psmouse_attribute, dattr)
+
+ssize_t psmouse_attr_show_helper(struct device *dev, struct device_attribute *attr,
+				 char *buf);
+ssize_t psmouse_attr_set_helper(struct device *dev, struct device_attribute *attr,
+				const char *buf, size_t count);
+
+#define __PSMOUSE_DEFINE_ATTR_VAR(_name, _mode, _data, _show, _set, _protect)	\
+static struct psmouse_attribute psmouse_attr_##_name = {			\
+	.dattr	= {								\
+		.attr	= {							\
+			.name	= __stringify(_name),				\
+			.mode	= _mode,					\
+		},								\
+		.show	= psmouse_attr_show_helper,				\
+		.store	= psmouse_attr_set_helper,				\
+	},									\
+	.data	= _data,							\
+	.show	= _show,							\
+	.set	= _set,								\
+	.protect = _protect,							\
+}
+
+#define __PSMOUSE_DEFINE_ATTR(_name, _mode, _data, _show, _set, _protect)	\
+	static ssize_t _show(struct psmouse *, void *, char *);			\
+	static ssize_t _set(struct psmouse *, void *, const char *, size_t);	\
+	__PSMOUSE_DEFINE_ATTR_VAR(_name, _mode, _data, _show, _set, _protect)
+
+#define PSMOUSE_DEFINE_ATTR(_name, _mode, _data, _show, _set)			\
+	__PSMOUSE_DEFINE_ATTR(_name, _mode, _data, _show, _set, true)
+
+#define PSMOUSE_DEFINE_RO_ATTR(_name, _mode, _data, _show)			\
+	static ssize_t _show(struct psmouse *, void *, char *);			\
+	__PSMOUSE_DEFINE_ATTR_VAR(_name, _mode, _data, _show, NULL, true)
+
+#define PSMOUSE_DEFINE_WO_ATTR(_name, _mode, _data, _set)			\
+	static ssize_t _set(struct psmouse *, void *, const char *, size_t);	\
+	__PSMOUSE_DEFINE_ATTR_VAR(_name, _mode, _data, NULL, _set, true)
+
+#ifndef psmouse_fmt
+#define psmouse_fmt(fmt)	KBUILD_BASENAME ": " fmt
+#endif
+
+#define psmouse_dbg(psmouse, format, ...)		\
+	dev_dbg(&(psmouse)->ps2dev.serio->dev,		\
+		psmouse_fmt(format), ##__VA_ARGS__)
+#define psmouse_info(psmouse, format, ...)		\
+	dev_info(&(psmouse)->ps2dev.serio->dev,		\
+		 psmouse_fmt(format), ##__VA_ARGS__)
+#define psmouse_warn(psmouse, format, ...)		\
+	dev_warn(&(psmouse)->ps2dev.serio->dev,		\
+		 psmouse_fmt(format), ##__VA_ARGS__)
+#define psmouse_err(psmouse, format, ...)		\
+	dev_err(&(psmouse)->ps2dev.serio->dev,		\
+		psmouse_fmt(format), ##__VA_ARGS__)
+#define psmouse_notice(psmouse, format, ...)		\
+	dev_notice(&(psmouse)->ps2dev.serio->dev,	\
+		   psmouse_fmt(format), ##__VA_ARGS__)
+#define psmouse_printk(level, psmouse, format, ...)	\
+	dev_printk(level,				\
+		   &(psmouse)->ps2dev.serio->dev,	\
+		   psmouse_fmt(format), ##__VA_ARGS__)
+
+#ifdef CONFIG_MOUSE_PS2_SMBUS
+
+int psmouse_smbus_module_init(void);
+void psmouse_smbus_module_exit(void);
+
+struct i2c_board_info;
+
+int psmouse_smbus_init(struct psmouse *psmouse,
+		       const struct i2c_board_info *board,
+		       const void *pdata, size_t pdata_size,
+		       bool need_deactivate,
+		       bool leave_breadcrumbs);
+void psmouse_smbus_cleanup(struct psmouse *psmouse);
+
+#else /* !CONFIG_MOUSE_PS2_SMBUS */
+
+static inline int psmouse_smbus_module_init(void)
+{
+	return 0;
+}
+
+static inline void psmouse_smbus_module_exit(void)
+{
+}
+
+static inline void psmouse_smbus_cleanup(struct psmouse *psmouse)
+{
+}
+
+#endif /* CONFIG_MOUSE_PS2_SMBUS */
+
+#endif /* _PSMOUSE_H */