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, 226 insertions, 0 deletions

diff --git a/drivers/usb/cdns3/drd.h b/drivers/usb/cdns3/drd.h
new file mode 100644
index 000000000..1e2aee14d
--- /dev/null
+++ b/drivers/usb/cdns3/drd.h
@@ -0,0 +1,226 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Cadence USB3 and USBSSP DRD header file.
+ *
+ * Copyright (C) 2018-2020 Cadence.
+ *
+ * Author: Pawel Laszczak <pawell@cadence.com>
+ */
+#ifndef __LINUX_CDNS3_DRD
+#define __LINUX_CDNS3_DRD
+
+#include <linux/usb/otg.h>
+#include "core.h"
+
+/*  DRD register interface for version v1 of cdns3 driver. */
+struct cdns3_otg_regs {
+	__le32 did;
+	__le32 rid;
+	__le32 capabilities;
+	__le32 reserved1;
+	__le32 cmd;
+	__le32 sts;
+	__le32 state;
+	__le32 reserved2;
+	__le32 ien;
+	__le32 ivect;
+	__le32 refclk;
+	__le32 tmr;
+	__le32 reserved3[4];
+	__le32 simulate;
+	__le32 override;
+	__le32 susp_ctrl;
+	__le32 phyrst_cfg;
+	__le32 anasts;
+	__le32 adp_ramp_time;
+	__le32 ctrl1;
+	__le32 ctrl2;
+};
+
+/*  DRD register interface for version v0 of cdns3 driver. */
+struct cdns3_otg_legacy_regs {
+	__le32 cmd;
+	__le32 sts;
+	__le32 state;
+	__le32 refclk;
+	__le32 ien;
+	__le32 ivect;
+	__le32 reserved1[3];
+	__le32 tmr;
+	__le32 reserved2[2];
+	__le32 version;
+	__le32 capabilities;
+	__le32 reserved3[2];
+	__le32 simulate;
+	__le32 reserved4[5];
+	__le32 ctrl1;
+};
+
+/* DRD register interface for cdnsp driver */
+struct cdnsp_otg_regs {
+	__le32 did;
+	__le32 rid;
+	__le32 cfgs1;
+	__le32 cfgs2;
+	__le32 cmd;
+	__le32 sts;
+	__le32 state;
+	__le32 ien;
+	__le32 ivect;
+	__le32 tmr;
+	__le32 simulate;
+	__le32 adpbc_sts;
+	__le32 adp_ramp_time;
+	__le32 adpbc_ctrl1;
+	__le32 adpbc_ctrl2;
+	__le32 override;
+	__le32 vbusvalid_dbnc_cfg;
+	__le32 sessvalid_dbnc_cfg;
+	__le32 susp_timing_ctrl;
+};
+
+/* CDNSP driver supports 0x000403xx Cadence USB controller family. */
+#define OTG_CDNSP_CHECK_DID(did) (((did) & GENMASK(31, 8)) == 0x00040300)
+
+/* CDNS3 driver supports 0x000402xx Cadence USB controller family. */
+#define OTG_CDNS3_CHECK_DID(did) (((did) & GENMASK(31, 8)) == 0x00040200)
+
+/*
+ * Common registers interface for both CDNS3 and CDNSP version of DRD.
+ */
+struct cdns_otg_common_regs {
+	__le32 cmd;
+	__le32 sts;
+	__le32 state;
+};
+
+/*
+ * Interrupt related registers. This registers are mapped in different
+ * location for CDNSP controller.
+ */
+struct cdns_otg_irq_regs {
+	__le32 ien;
+	__le32 ivect;
+};
+
+/* CDNS_RID - bitmasks */
+#define CDNS_RID(p)			((p) & GENMASK(15, 0))
+
+/* CDNS_VID - bitmasks */
+#define CDNS_DID(p)			((p) & GENMASK(31, 0))
+
+/* OTGCMD - bitmasks */
+/* "Request the bus for Device mode. */
+#define OTGCMD_DEV_BUS_REQ		BIT(0)
+/* Request the bus for Host mode */
+#define OTGCMD_HOST_BUS_REQ		BIT(1)
+/* Enable OTG mode. */
+#define OTGCMD_OTG_EN			BIT(2)
+/* Disable OTG mode */
+#define OTGCMD_OTG_DIS			BIT(3)
+/*"Configure OTG as A-Device. */
+#define OTGCMD_A_DEV_EN			BIT(4)
+/*"Configure OTG as A-Device. */
+#define OTGCMD_A_DEV_DIS		BIT(5)
+/* Drop the bus for Device mod	e. */
+#define OTGCMD_DEV_BUS_DROP		BIT(8)
+/* Drop the bus for Host mode*/
+#define OTGCMD_HOST_BUS_DROP		BIT(9)
+/* Power Down USBSS-DEV - only for CDNS3.*/
+#define OTGCMD_DEV_POWER_OFF		BIT(11)
+/* Power Down CDNSXHCI - only for CDNS3. */
+#define OTGCMD_HOST_POWER_OFF		BIT(12)
+
+/* OTGIEN - bitmasks */
+/* ID change interrupt enable */
+#define OTGIEN_ID_CHANGE_INT		BIT(0)
+/* Vbusvalid fall detected interrupt enable.*/
+#define OTGIEN_VBUSVALID_RISE_INT	BIT(4)
+/* Vbusvalid fall detected interrupt enable */
+#define OTGIEN_VBUSVALID_FALL_INT	BIT(5)
+
+/* OTGSTS - bitmasks */
+/*
+ * Current value of the ID pin. It is only valid when idpullup in
+ *  OTGCTRL1_TYPE register is set to '1'.
+ */
+#define OTGSTS_ID_VALUE			BIT(0)
+/* Current value of the vbus_valid */
+#define OTGSTS_VBUS_VALID		BIT(1)
+/* Current value of the b_sess_vld */
+#define OTGSTS_SESSION_VALID		BIT(2)
+/*Device mode is active*/
+#define OTGSTS_DEV_ACTIVE		BIT(3)
+/* Host mode is active. */
+#define OTGSTS_HOST_ACTIVE		BIT(4)
+/* OTG Controller not ready. */
+#define OTGSTS_OTG_NRDY_MASK		BIT(11)
+#define OTGSTS_OTG_NRDY(p)		((p) & OTGSTS_OTG_NRDY_MASK)
+/*
+ * Value of the strap pins for:
+ * CDNS3:
+ * 000 - no default configuration
+ * 010 - Controller initiall configured as Host
+ * 100 - Controller initially configured as Device
+ * CDNSP:
+ * 000 - No default configuration.
+ * 010 - Controller initiall configured as Host.
+ * 100 - Controller initially configured as Device.
+ */
+#define OTGSTS_STRAP(p)			(((p) & GENMASK(14, 12)) >> 12)
+#define OTGSTS_STRAP_NO_DEFAULT_CFG	0x00
+#define OTGSTS_STRAP_HOST_OTG		0x01
+#define OTGSTS_STRAP_HOST		0x02
+#define OTGSTS_STRAP_GADGET		0x04
+#define OTGSTS_CDNSP_STRAP_HOST		0x01
+#define OTGSTS_CDNSP_STRAP_GADGET	0x02
+
+/* Host mode is turned on. */
+#define OTGSTS_CDNS3_XHCI_READY		BIT(26)
+#define OTGSTS_CDNSP_XHCI_READY		BIT(27)
+
+/* "Device mode is turned on .*/
+#define OTGSTS_CDNS3_DEV_READY		BIT(27)
+#define OTGSTS_CDNSP_DEV_READY		BIT(26)
+
+/* OTGSTATE- bitmasks */
+#define OTGSTATE_DEV_STATE_MASK		GENMASK(2, 0)
+#define OTGSTATE_HOST_STATE_MASK	GENMASK(5, 3)
+#define OTGSTATE_HOST_STATE_IDLE	0x0
+#define OTGSTATE_HOST_STATE_VBUS_FALL	0x7
+#define OTGSTATE_HOST_STATE(p)		(((p) & OTGSTATE_HOST_STATE_MASK) >> 3)
+
+/* OTGREFCLK - bitmasks */
+#define OTGREFCLK_STB_CLK_SWITCH_EN	BIT(31)
+
+/* SUPS_CTRL - bitmasks */
+#define SUSP_CTRL_SUSPEND_RESIDENCY_ENABLE	BIT(17)
+
+/* OVERRIDE - bitmasks */
+#define OVERRIDE_IDPULLUP		BIT(0)
+/* Only for CDNS3_CONTROLLER_V0 version */
+#define OVERRIDE_IDPULLUP_V0		BIT(24)
+/* Vbusvalid/Sesvalid override select. */
+#define OVERRIDE_SESS_VLD_SEL		BIT(10)
+
+/* PHYRST_CFG - bitmasks */
+#define PHYRST_CFG_PHYRST_A_ENABLE     BIT(0)
+
+#define CDNS3_ID_PERIPHERAL		1
+#define CDNS3_ID_HOST			0
+
+bool cdns_is_host(struct cdns *cdns);
+bool cdns_is_device(struct cdns *cdns);
+int cdns_get_id(struct cdns *cdns);
+int cdns_get_vbus(struct cdns *cdns);
+void cdns_clear_vbus(struct cdns *cdns);
+void cdns_set_vbus(struct cdns *cdns);
+int cdns_drd_init(struct cdns *cdns);
+int cdns_drd_exit(struct cdns *cdns);
+int cdns_drd_update_mode(struct cdns *cdns);
+int cdns_drd_gadget_on(struct cdns *cdns);
+void cdns_drd_gadget_off(struct cdns *cdns);
+int cdns_drd_host_on(struct cdns *cdns);
+void cdns_drd_host_off(struct cdns *cdns);
+bool cdns_power_is_lost(struct cdns *cdns);
+#endif /* __LINUX_CDNS3_DRD */