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, 54 insertions, 0 deletions

diff --git a/drivers/bluetooth/Makefile b/drivers/bluetooth/Makefile
new file mode 100644
index 000000000..e6b1c1180
--- /dev/null
+++ b/drivers/bluetooth/Makefile
@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the Linux Bluetooth HCI device drivers.
+#
+
+obj-$(CONFIG_BT_HCIVHCI)	+= hci_vhci.o
+obj-$(CONFIG_BT_HCIUART)	+= hci_uart.o
+obj-$(CONFIG_BT_HCIBCM203X)	+= bcm203x.o
+obj-$(CONFIG_BT_HCIBCM4377)	+= hci_bcm4377.o
+obj-$(CONFIG_BT_HCIBPA10X)	+= bpa10x.o
+obj-$(CONFIG_BT_HCIBFUSB)	+= bfusb.o
+
+obj-$(CONFIG_BT_HCIBTUSB)	+= btusb.o
+obj-$(CONFIG_BT_HCIBTSDIO)	+= btsdio.o
+
+obj-$(CONFIG_BT_INTEL)		+= btintel.o
+obj-$(CONFIG_BT_INTEL_PCIE)	+= btintel_pcie.o btintel.o
+obj-$(CONFIG_BT_ATH3K)		+= ath3k.o
+obj-$(CONFIG_BT_MRVL)		+= btmrvl.o
+obj-$(CONFIG_BT_MRVL_SDIO)	+= btmrvl_sdio.o
+obj-$(CONFIG_BT_MTKSDIO)	+= btmtksdio.o
+obj-$(CONFIG_BT_MTKUART)	+= btmtkuart.o
+obj-$(CONFIG_BT_QCOMSMD)	+= btqcomsmd.o
+obj-$(CONFIG_BT_BCM)		+= btbcm.o
+obj-$(CONFIG_BT_RTL)		+= btrtl.o
+obj-$(CONFIG_BT_QCA)		+= btqca.o
+obj-$(CONFIG_BT_MTK)		+= btmtk.o
+
+obj-$(CONFIG_BT_VIRTIO)		+= virtio_bt.o
+obj-$(CONFIG_BT_NXPUART)	+= btnxpuart.o
+
+obj-$(CONFIG_BT_HCIUART_NOKIA)	+= hci_nokia.o
+
+obj-$(CONFIG_BT_HCIRSI)		+= btrsi.o
+
+btmrvl-y			:= btmrvl_main.o
+btmrvl-$(CONFIG_DEBUG_FS)	+= btmrvl_debugfs.o
+
+hci_uart-y				:= hci_ldisc.o
+hci_uart-$(CONFIG_BT_HCIUART_SERDEV)	+= hci_serdev.o
+hci_uart-$(CONFIG_BT_HCIUART_H4)	+= hci_h4.o
+hci_uart-$(CONFIG_BT_HCIUART_BCSP)	+= hci_bcsp.o
+hci_uart-$(CONFIG_BT_HCIUART_LL)	+= hci_ll.o
+hci_uart-$(CONFIG_BT_HCIUART_ATH3K)	+= hci_ath.o
+hci_uart-$(CONFIG_BT_HCIUART_3WIRE)	+= hci_h5.o
+hci_uart-$(CONFIG_BT_HCIUART_INTEL)	+= hci_intel.o
+hci_uart-$(CONFIG_BT_HCIUART_BCM)	+= hci_bcm.o
+hci_uart-$(CONFIG_BT_HCIUART_QCA)	+= hci_qca.o
+hci_uart-$(CONFIG_BT_HCIUART_AG6XX)	+= hci_ag6xx.o
+hci_uart-$(CONFIG_BT_HCIUART_MRVL)	+= hci_mrvl.o
+hci_uart-$(CONFIG_BT_HCIUART_AML)	+= hci_aml.o
+hci_uart-objs				:= $(hci_uart-y)
+
+CONTEXT_ANALYSIS := y