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, 67 insertions, 0 deletions

diff --git a/drivers/usb/Makefile b/drivers/usb/Makefile
new file mode 100644
index 000000000..eecbd631f
--- /dev/null
+++ b/drivers/usb/Makefile
@@ -0,0 +1,67 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the kernel USB device drivers.
+#
+
+# Object files in subdirectories
+
+obj-$(CONFIG_USB_COMMON)	+= common/
+obj-$(CONFIG_USB)		+= core/
+obj-$(CONFIG_USB_SUPPORT)	+= phy/
+
+obj-$(CONFIG_USB_DWC3)		+= dwc3/
+obj-$(CONFIG_USB_DWC2)		+= dwc2/
+obj-$(CONFIG_USB_ISP1760)	+= isp1760/
+
+obj-$(CONFIG_USB_CDNS_SUPPORT)	+= cdns3/
+
+obj-$(CONFIG_USB_FOTG210)	+= fotg210/
+
+obj-$(CONFIG_USB_MON)		+= mon/
+obj-$(CONFIG_USB_MTU3)		+= mtu3/
+
+obj-$(CONFIG_USB_PCI)		+= host/
+obj-$(CONFIG_USB_EHCI_HCD)	+= host/
+obj-$(CONFIG_USB_ISP116X_HCD)	+= host/
+obj-$(CONFIG_USB_OHCI_HCD)	+= host/
+obj-$(CONFIG_USB_UHCI_HCD)	+= host/
+obj-$(CONFIG_USB_FHCI_HCD)	+= host/
+obj-$(CONFIG_USB_XHCI_HCD)	+= host/
+obj-$(CONFIG_USB_SL811_HCD)	+= host/
+obj-$(CONFIG_USB_R8A66597_HCD)	+= host/
+obj-$(CONFIG_USB_FSL_USB2)	+= host/
+obj-$(CONFIG_USB_FOTG210_HCD)	+= host/
+obj-$(CONFIG_USB_MAX3421_HCD)	+= host/
+obj-$(CONFIG_USB_XEN_HCD)	+= host/
+
+obj-$(CONFIG_USB_C67X00_HCD)	+= c67x00/
+
+obj-$(CONFIG_USB_ACM)		+= class/
+obj-$(CONFIG_USB_PRINTER)	+= class/
+obj-$(CONFIG_USB_WDM)		+= class/
+obj-$(CONFIG_USB_TMC)		+= class/
+
+obj-$(CONFIG_USB_STORAGE)	+= storage/
+obj-$(CONFIG_USB)		+= storage/
+
+obj-$(CONFIG_USB_MDC800)	+= image/
+obj-$(CONFIG_USB_MICROTEK)	+= image/
+
+obj-$(CONFIG_USB_SERIAL)	+= serial/
+
+obj-$(CONFIG_USB)		+= misc/
+obj-$(CONFIG_EARLY_PRINTK_USB)	+= early/
+
+obj-$(CONFIG_USB_ATM)		+= atm/
+obj-$(CONFIG_USB_SPEEDTOUCH)	+= atm/
+
+obj-$(CONFIG_USB_MUSB_HDRC)	+= musb/
+obj-$(CONFIG_USB_CHIPIDEA)	+= chipidea/
+obj-$(CONFIG_USB_RENESAS_USBHS)	+= renesas_usbhs/
+obj-$(CONFIG_USB_GADGET)	+= gadget/
+
+obj-$(CONFIG_USBIP_CORE)	+= usbip/
+
+obj-$(CONFIG_TYPEC)		+= typec/
+
+obj-$(CONFIG_USB_ROLE_SWITCH)	+= roles/