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, 37 insertions, 0 deletions

diff --git a/drivers/usb/misc/Makefile b/drivers/usb/misc/Makefile
new file mode 100644
index 000000000..494ab0377
--- /dev/null
+++ b/drivers/usb/misc/Makefile
@@ -0,0 +1,37 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the rest of the USB drivers
+# (the ones that don't fit into any other categories)
+#
+obj-$(CONFIG_USB_ADUTUX)		+= adutux.o
+obj-$(CONFIG_USB_APPLEDISPLAY)		+= appledisplay.o
+obj-$(CONFIG_USB_CYPRESS_CY7C63)	+= cypress_cy7c63.o
+obj-$(CONFIG_USB_CYTHERM)		+= cytherm.o
+obj-$(CONFIG_USB_EMI26)			+= emi26.o
+obj-$(CONFIG_USB_EMI62)			+= emi62.o
+obj-$(CONFIG_USB_EZUSB_FX2)		+= ezusb.o
+obj-$(CONFIG_APPLE_MFI_FASTCHARGE)	+= apple-mfi-fastcharge.o
+obj-$(CONFIG_USB_LJCA)			+= usb-ljca.o
+obj-$(CONFIG_USB_USBIO)			+= usbio.o
+obj-$(CONFIG_USB_IDMOUSE)		+= idmouse.o
+obj-$(CONFIG_USB_IOWARRIOR)		+= iowarrior.o
+obj-$(CONFIG_USB_ISIGHTFW)		+= isight_firmware.o
+obj-$(CONFIG_USB_LCD)			+= usblcd.o
+obj-$(CONFIG_USB_LD)			+= ldusb.o
+obj-$(CONFIG_USB_LEGOTOWER)		+= legousbtower.o
+obj-$(CONFIG_USB_QCOM_EUD)		+= qcom_eud.o
+obj-$(CONFIG_USB_TEST)			+= usbtest.o
+obj-$(CONFIG_USB_EHSET_TEST_FIXTURE)    += ehset.o
+obj-$(CONFIG_USB_TRANCEVIBRATOR)	+= trancevibrator.o
+obj-$(CONFIG_USB_USS720)		+= uss720.o
+obj-$(CONFIG_USB_SEVSEG)		+= usbsevseg.o
+obj-$(CONFIG_USB_YUREX)			+= yurex.o
+obj-$(CONFIG_USB_HUB_USB251XB)		+= usb251xb.o
+obj-$(CONFIG_USB_HSIC_USB3503)		+= usb3503.o
+obj-$(CONFIG_USB_HSIC_USB4604)		+= usb4604.o
+obj-$(CONFIG_USB_CHAOSKEY)		+= chaoskey.o
+
+obj-$(CONFIG_USB_SISUSBVGA)		+= sisusbvga/
+obj-$(CONFIG_USB_LINK_LAYER_TEST)	+= lvstest.o
+obj-$(CONFIG_BRCM_USB_PINMAP)		+= brcmstb-usb-pinmap.o
+obj-$(CONFIG_USB_ONBOARD_DEV)		+= onboard_usb_dev.o