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, 114 insertions, 0 deletions

diff --git a/drivers/input/mouse/sentelic.h b/drivers/input/mouse/sentelic.h
new file mode 100644
index 000000000..02cac0e7a
--- /dev/null
+++ b/drivers/input/mouse/sentelic.h
@@ -0,0 +1,114 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*-
+ * Finger Sensing Pad PS/2 mouse driver.
+ *
+ * Copyright (C) 2005-2007 Asia Vital Components Co., Ltd.
+ * Copyright (C) 2005-2012 Tai-hwa Liang, Sentelic Corporation.
+ */
+
+#ifndef	__SENTELIC_H
+#define	__SENTELIC_H
+
+/* Finger-sensing Pad information registers */
+#define	FSP_REG_DEVICE_ID	0x00
+#define	FSP_REG_VERSION		0x01
+#define	FSP_REG_REVISION	0x04
+#define	FSP_REG_TMOD_STATUS1	0x0B
+#define	FSP_BIT_NO_ROTATION	BIT(3)
+#define	FSP_REG_PAGE_CTRL	0x0F
+
+/* Finger-sensing Pad control registers */
+#define	FSP_REG_SYSCTL1		0x10
+#define	FSP_BIT_EN_REG_CLK	BIT(5)
+#define	FSP_REG_TMOD_STATUS	0x20
+#define	FSP_REG_OPC_QDOWN	0x31
+#define	FSP_BIT_EN_OPC_TAG	BIT(7)
+#define	FSP_REG_OPTZ_XLO	0x34
+#define	FSP_REG_OPTZ_XHI	0x35
+#define	FSP_REG_OPTZ_YLO	0x36
+#define	FSP_REG_OPTZ_YHI	0x37
+#define	FSP_REG_SYSCTL5		0x40
+#define	FSP_BIT_90_DEGREE	BIT(0)
+#define	FSP_BIT_EN_MSID6	BIT(1)
+#define	FSP_BIT_EN_MSID7	BIT(2)
+#define	FSP_BIT_EN_MSID8	BIT(3)
+#define	FSP_BIT_EN_AUTO_MSID8	BIT(5)
+#define	FSP_BIT_EN_PKT_G0	BIT(6)
+
+#define	FSP_REG_ONPAD_CTL	0x43
+#define	FSP_BIT_ONPAD_ENABLE	BIT(0)
+#define	FSP_BIT_ONPAD_FBBB	BIT(1)
+#define	FSP_BIT_FIX_VSCR	BIT(3)
+#define	FSP_BIT_FIX_HSCR	BIT(5)
+#define	FSP_BIT_DRAG_LOCK	BIT(6)
+
+#define	FSP_REG_SWC1		(0x90)
+#define	FSP_BIT_SWC1_EN_ABS_1F	BIT(0)
+#define	FSP_BIT_SWC1_EN_GID	BIT(1)
+#define	FSP_BIT_SWC1_EN_ABS_2F	BIT(2)
+#define	FSP_BIT_SWC1_EN_FUP_OUT	BIT(3)
+#define	FSP_BIT_SWC1_EN_ABS_CON	BIT(4)
+#define	FSP_BIT_SWC1_GST_GRP0	BIT(5)
+#define	FSP_BIT_SWC1_GST_GRP1	BIT(6)
+#define	FSP_BIT_SWC1_BX_COMPAT	BIT(7)
+
+#define	FSP_PAGE_0B		(0x0b)
+#define	FSP_PAGE_82		(0x82)
+#define	FSP_PAGE_DEFAULT	FSP_PAGE_82
+
+#define	FSP_REG_SN0		(0x40)
+#define	FSP_REG_SN1		(0x41)
+#define	FSP_REG_SN2		(0x42)
+
+/* Finger-sensing Pad packet formating related definitions */
+
+/* absolute packet type */
+#define	FSP_PKT_TYPE_NORMAL	(0x00)
+#define	FSP_PKT_TYPE_ABS	(0x01)
+#define	FSP_PKT_TYPE_NOTIFY	(0x02)
+#define	FSP_PKT_TYPE_NORMAL_OPC	(0x03)
+#define	FSP_PKT_TYPE_SHIFT	(6)
+
+/* bit definitions for the first byte of report packet */
+#define	FSP_PB0_LBTN		BIT(0)
+#define	FSP_PB0_RBTN		BIT(1)
+#define	FSP_PB0_MBTN		BIT(2)
+#define	FSP_PB0_MFMC_FGR2	FSP_PB0_MBTN
+#define	FSP_PB0_MUST_SET	BIT(3)
+#define	FSP_PB0_PHY_BTN		BIT(4)
+#define	FSP_PB0_MFMC		BIT(5)
+
+/* hardware revisions */
+#define	FSP_VER_STL3888_A4	(0xC1)
+#define	FSP_VER_STL3888_B0	(0xD0)
+#define	FSP_VER_STL3888_B1	(0xD1)
+#define	FSP_VER_STL3888_B2	(0xD2)
+#define	FSP_VER_STL3888_C0	(0xE0)
+#define	FSP_VER_STL3888_C1	(0xE1)
+#define	FSP_VER_STL3888_D0	(0xE2)
+#define	FSP_VER_STL3888_D1	(0xE3)
+#define	FSP_VER_STL3888_E0	(0xE4)
+
+#ifdef __KERNEL__
+
+struct fsp_data {
+	unsigned char	ver;		/* hardware version */
+	unsigned char	rev;		/* hardware revison */
+	unsigned int	buttons;	/* Number of buttons */
+	unsigned int	flags;
+#define	FSPDRV_FLAG_EN_OPC	(0x001)	/* enable on-pad clicking */
+
+	bool		vscroll;	/* Vertical scroll zone enabled */
+	bool		hscroll;	/* Horizontal scroll zone enabled */
+
+	unsigned char	last_reg;	/* Last register we requested read from */
+	unsigned char	last_val;
+	unsigned int	last_mt_fgr;	/* Last seen finger(multitouch) */
+};
+
+extern int fsp_detect(struct psmouse *psmouse, bool set_properties);
+extern int fsp_init(struct psmouse *psmouse);
+
+#endif	/* __KERNEL__ */
+
+#endif	/* !__SENTELIC_H */