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, 171 insertions, 0 deletions

diff --git a/drivers/phy/broadcom/phy-brcm-usb-init.h b/drivers/phy/broadcom/phy-brcm-usb-init.h
new file mode 100644
index 000000000..4c7be78d0
--- /dev/null
+++ b/drivers/phy/broadcom/phy-brcm-usb-init.h
@@ -0,0 +1,171 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2014-2017 Broadcom
+ */
+
+#ifndef _USB_BRCM_COMMON_INIT_H
+#define _USB_BRCM_COMMON_INIT_H
+
+#include <linux/regmap.h>
+
+#define USB_CTLR_MODE_HOST 0
+#define USB_CTLR_MODE_DEVICE 1
+#define USB_CTLR_MODE_DRD 2
+#define USB_CTLR_MODE_TYPEC_PD 3
+
+enum brcmusb_reg_sel {
+	BRCM_REGS_CTRL = 0,
+	BRCM_REGS_XHCI_EC,
+	BRCM_REGS_XHCI_GBL,
+	BRCM_REGS_USB_PHY,
+	BRCM_REGS_USB_MDIO,
+	BRCM_REGS_BDC_EC,
+	BRCM_REGS_MAX
+};
+
+#define USB_CTRL_REG(base, reg)	((void __iomem *)base + USB_CTRL_##reg)
+#define USB_XHCI_EC_REG(base, reg) ((void __iomem *)base + USB_XHCI_EC_##reg)
+#define USB_CTRL_MASK(reg, field) \
+	USB_CTRL_##reg##_##field##_MASK
+#define USB_CTRL_SET(base, reg, field)	\
+	brcm_usb_ctrl_set(USB_CTRL_REG(base, reg),	\
+			  USB_CTRL_##reg##_##field##_MASK)
+#define USB_CTRL_UNSET(base, reg, field)	\
+	brcm_usb_ctrl_unset(USB_CTRL_REG(base, reg),		\
+			    USB_CTRL_##reg##_##field##_MASK)
+
+#define USB_XHCI_GBL_REG(base, reg) ((void __iomem *)base + USB_XHCI_GBL_##reg)
+#define USB_XHCI_GBL_SET(base, reg, field) \
+	brcm_usb_ctrl_set(USB_XHCI_GBL_REG(base, reg), \
+			  USB_XHCI_GBL_##reg##_##field##_MASK)
+#define USB_XHCI_GBL_UNSET(base, reg, field) \
+	brcm_usb_ctrl_unset(USB_XHCI_GBL_REG(base, reg), \
+			    USB_XHCI_GBL_##reg##_##field##_MASK)
+
+struct  brcm_usb_init_params;
+
+struct brcm_usb_init_ops {
+	void (*init_ipp)(struct brcm_usb_init_params *params);
+	void (*init_common)(struct brcm_usb_init_params *params);
+	void (*init_eohci)(struct brcm_usb_init_params *params);
+	void (*init_xhci)(struct brcm_usb_init_params *params);
+	void (*uninit_common)(struct brcm_usb_init_params *params);
+	void (*uninit_eohci)(struct brcm_usb_init_params *params);
+	void (*uninit_xhci)(struct brcm_usb_init_params *params);
+	int  (*get_dual_select)(struct brcm_usb_init_params *params);
+	void (*set_dual_select)(struct brcm_usb_init_params *params);
+};
+
+struct  brcm_usb_init_params {
+	void __iomem *regs[BRCM_REGS_MAX];
+	int ioc;
+	int ipp;
+	int supported_port_modes;
+	int port_mode;
+	u32 family_id;
+	u32 product_id;
+	int selected_family;
+	const char *family_name;
+	const u32 *usb_reg_bits_map;
+	const struct brcm_usb_init_ops *ops;
+	struct regmap *syscon_piarbctl;
+	bool wake_enabled;
+};
+
+void brcm_usb_dvr_init_74110(struct brcm_usb_init_params *params);
+void brcm_usb_dvr_init_4908(struct brcm_usb_init_params *params);
+void brcm_usb_dvr_init_7445(struct brcm_usb_init_params *params);
+void brcm_usb_dvr_init_7216(struct brcm_usb_init_params *params);
+void brcm_usb_dvr_init_7211b0(struct brcm_usb_init_params *params);
+
+static inline u32 brcm_usb_readl(void __iomem *addr)
+{
+	/*
+	 * MIPS endianness is configured by boot strap, which also reverses all
+	 * bus endianness (i.e., big-endian CPU + big endian bus ==> native
+	 * endian I/O).
+	 *
+	 * Other architectures (e.g., ARM) either do not support big endian, or
+	 * else leave I/O in little endian mode.
+	 */
+	if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
+		return __raw_readl(addr);
+	else
+		return readl_relaxed(addr);
+}
+
+static inline void brcm_usb_writel(u32 val, void __iomem *addr)
+{
+	/* See brcmnand_readl() comments */
+	if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
+		__raw_writel(val, addr);
+	else
+		writel_relaxed(val, addr);
+}
+
+static inline void brcm_usb_ctrl_unset(void __iomem *reg, u32 mask)
+{
+	brcm_usb_writel(brcm_usb_readl(reg) & ~(mask), reg);
+};
+
+static inline void brcm_usb_ctrl_set(void __iomem *reg, u32 mask)
+{
+	brcm_usb_writel(brcm_usb_readl(reg) | (mask), reg);
+};
+
+static inline void brcm_usb_init_ipp(struct brcm_usb_init_params *ini)
+{
+	if (ini->ops->init_ipp)
+		ini->ops->init_ipp(ini);
+}
+
+static inline void brcm_usb_init_common(struct brcm_usb_init_params *ini)
+{
+	if (ini->ops->init_common)
+		ini->ops->init_common(ini);
+}
+
+static inline void brcm_usb_init_eohci(struct brcm_usb_init_params *ini)
+{
+	if (ini->ops->init_eohci)
+		ini->ops->init_eohci(ini);
+}
+
+static inline void brcm_usb_init_xhci(struct brcm_usb_init_params *ini)
+{
+	if (ini->ops->init_xhci)
+		ini->ops->init_xhci(ini);
+}
+
+static inline void brcm_usb_uninit_common(struct brcm_usb_init_params *ini)
+{
+	if (ini->ops->uninit_common)
+		ini->ops->uninit_common(ini);
+}
+
+static inline void brcm_usb_uninit_eohci(struct brcm_usb_init_params *ini)
+{
+	if (ini->ops->uninit_eohci)
+		ini->ops->uninit_eohci(ini);
+}
+
+static inline void brcm_usb_uninit_xhci(struct brcm_usb_init_params *ini)
+{
+	if (ini->ops->uninit_xhci)
+		ini->ops->uninit_xhci(ini);
+}
+
+static inline int brcm_usb_get_dual_select(struct brcm_usb_init_params *ini)
+{
+	if (ini->ops->get_dual_select)
+		return ini->ops->get_dual_select(ini);
+	return 0;
+}
+
+static inline void brcm_usb_set_dual_select(struct brcm_usb_init_params *ini)
+{
+	if (ini->ops->set_dual_select)
+		ini->ops->set_dual_select(ini);
+}
+
+#endif /* _USB_BRCM_COMMON_INIT_H */