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, 44 insertions, 0 deletions

diff --git a/drivers/net/usb/Makefile b/drivers/net/usb/Makefile
new file mode 100644
index 000000000..4964f7b32
--- /dev/null
+++ b/drivers/net/usb/Makefile
@@ -0,0 +1,44 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for USB Network drivers
+#
+
+obj-$(CONFIG_USB_CATC)		+= catc.o
+obj-$(CONFIG_USB_KAWETH)	+= kaweth.o
+obj-$(CONFIG_USB_PEGASUS)	+= pegasus.o
+obj-$(CONFIG_USB_RTL8150)	+= rtl8150.o
+obj-$(CONFIG_USB_RTL8152)	+= r8152.o
+obj-$(CONFIG_USB_HSO)		+= hso.o
+obj-$(CONFIG_USB_LAN78XX)	+= lan78xx.o
+obj-$(CONFIG_USB_NET_AX8817X)	+= asix.o
+asix-y := asix_devices.o asix_common.o ax88172a.o
+obj-$(CONFIG_USB_NET_AX88179_178A)      += ax88179_178a.o
+obj-$(CONFIG_USB_NET_CDCETHER)	+= cdc_ether.o
+obj-$(CONFIG_USB_NET_CDC_EEM)	+= cdc_eem.o
+obj-$(CONFIG_USB_NET_DM9601)	+= dm9601.o
+obj-$(CONFIG_USB_NET_SR9700)	+= sr9700.o
+obj-$(CONFIG_USB_NET_SR9800)	+= sr9800.o
+obj-$(CONFIG_USB_NET_SMSC75XX)	+= smsc75xx.o
+obj-$(CONFIG_USB_NET_SMSC95XX)	+= smsc95xx.o
+obj-$(CONFIG_USB_NET_GL620A)	+= gl620a.o
+obj-$(CONFIG_USB_NET_NET1080)	+= net1080.o
+obj-$(CONFIG_USB_NET_PLUSB)	+= plusb.o
+obj-$(CONFIG_USB_NET_RNDIS_HOST)	+= rndis_host.o
+obj-$(CONFIG_USB_NET_CDC_SUBSET_ENABLE)	+= cdc_subset.o
+obj-$(CONFIG_USB_NET_ZAURUS)	+= zaurus.o
+obj-$(CONFIG_USB_NET_MCS7830)	+= mcs7830.o
+obj-$(CONFIG_USB_USBNET)	+= usbnet.o
+obj-$(CONFIG_USB_NET_INT51X1)	+= int51x1.o
+obj-$(CONFIG_USB_CDC_PHONET)	+= cdc-phonet.o
+obj-$(CONFIG_USB_NET_KALMIA)	+= kalmia.o
+obj-$(CONFIG_USB_IPHETH)	+= ipheth.o
+obj-$(CONFIG_USB_SIERRA_NET)	+= sierra_net.o
+obj-$(CONFIG_USB_NET_CX82310_ETH)	+= cx82310_eth.o
+obj-$(CONFIG_USB_NET_CDC_NCM)	+= cdc_ncm.o
+obj-$(CONFIG_USB_NET_HUAWEI_CDC_NCM)	+= huawei_cdc_ncm.o
+obj-$(CONFIG_USB_VL600)		+= lg-vl600.o
+obj-$(CONFIG_USB_NET_QMI_WWAN)	+= qmi_wwan.o
+obj-$(CONFIG_USB_NET_CDC_MBIM)	+= cdc_mbim.o
+obj-$(CONFIG_USB_NET_CH9200)	+= ch9200.o
+obj-$(CONFIG_USB_NET_AQC111)	+= aqc111.o
+obj-$(CONFIG_USB_RTL8153_ECM)	+= r8153_ecm.o