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, 73 insertions, 0 deletions

diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
new file mode 100644
index 000000000..e8d8d5d88
--- /dev/null
+++ b/drivers/misc/Makefile
@@ -0,0 +1,73 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for misc devices that really don't fit anywhere else.
+#
+
+obj-$(CONFIG_IBMVMC)		+= ibmvmc.o
+obj-$(CONFIG_AD525X_DPOT)	+= ad525x_dpot.o
+obj-$(CONFIG_AD525X_DPOT_I2C)	+= ad525x_dpot-i2c.o
+obj-$(CONFIG_AD525X_DPOT_SPI)	+= ad525x_dpot-spi.o
+obj-$(CONFIG_ATMEL_SSC)		+= atmel-ssc.o
+obj-$(CONFIG_DUMMY_IRQ)		+= dummy-irq.o
+obj-$(CONFIG_ICS932S401)	+= ics932s401.o
+obj-$(CONFIG_LKDTM)		+= lkdtm/
+obj-$(CONFIG_TI_FPC202)		+= ti_fpc202.o
+obj-$(CONFIG_TIFM_CORE)       	+= tifm_core.o
+obj-$(CONFIG_TIFM_7XX1)       	+= tifm_7xx1.o
+obj-$(CONFIG_PHANTOM)		+= phantom.o
+obj-$(CONFIG_RPMB)		+= rpmb-core.o
+obj-$(CONFIG_QCOM_COINCELL)	+= qcom-coincell.o
+obj-$(CONFIG_QCOM_FASTRPC)	+= fastrpc.o
+obj-$(CONFIG_SENSORS_BH1770)	+= bh1770glc.o
+obj-$(CONFIG_ENCLOSURE_SERVICES) += enclosure.o
+obj-$(CONFIG_KGDB_TESTS)	+= kgdbts.o
+obj-$(CONFIG_SMPRO_ERRMON)	+= smpro-errmon.o
+obj-$(CONFIG_SMPRO_MISC)	+= smpro-misc.o
+obj-$(CONFIG_CS5535_MFGPT)	+= cs5535-mfgpt.o
+obj-$(CONFIG_GEHC_ACHC)		+= gehc-achc.o
+obj-$(CONFIG_HP_ILO)		+= hpilo.o
+obj-$(CONFIG_APDS9802ALS)	+= apds9802als.o
+obj-$(CONFIG_ISL29003)		+= isl29003.o
+obj-$(CONFIG_ISL29020)		+= isl29020.o
+obj-$(CONFIG_SENSORS_TSL2550)	+= tsl2550.o
+obj-$(CONFIG_DS1682)		+= ds1682.o
+obj-$(CONFIG_C2PORT)		+= c2port/
+obj-$(CONFIG_HMC6352)		+= hmc6352.o
+obj-y				+= eeprom/
+obj-y				+= cb710/
+obj-$(CONFIG_VMWARE_BALLOON)	+= vmw_balloon.o
+obj-$(CONFIG_PCH_PHUB)		+= pch_phub.o
+obj-y				+= lis3lv02d/
+obj-$(CONFIG_ALTERA_STAPL)	+=altera-stapl/
+obj-$(CONFIG_INTEL_MEI)		+= mei/
+obj-$(CONFIG_VMWARE_VMCI)	+= vmw_vmci/
+obj-$(CONFIG_LATTICE_ECP3_CONFIG)	+= lattice-ecp3-config.o
+obj-$(CONFIG_SRAM)		+= sram.o
+obj-$(CONFIG_SRAM_EXEC)		+= sram-exec.o
+obj-$(CONFIG_GENWQE)		+= genwqe/
+obj-$(CONFIG_DW_XDATA_PCIE)	+= dw-xdata-pcie.o
+obj-$(CONFIG_PCI_ENDPOINT_TEST)	+= pci_endpoint_test.o
+obj-$(CONFIG_OCXL)		+= ocxl/
+obj-$(CONFIG_BCM_VK)		+= bcm-vk/
+obj-y				+= cardreader/
+obj-$(CONFIG_PVPANIC)   	+= pvpanic/
+obj-$(CONFIG_UACCE)		+= uacce/
+obj-$(CONFIG_XILINX_SDFEC)	+= xilinx_sdfec.o
+obj-$(CONFIG_NTSYNC)		+= ntsync.o
+obj-$(CONFIG_HI6421V600_IRQ)	+= hi6421v600-irq.o
+obj-$(CONFIG_OPEN_DICE)		+= open-dice.o
+obj-$(CONFIG_GP_PCI1XXXX)	+= mchp_pci1xxxx/
+obj-$(CONFIG_VCPU_STALL_DETECTOR)	+= vcpu_stall_detector.o
+obj-$(CONFIG_TMR_MANAGER)      += xilinx_tmr_manager.o
+obj-$(CONFIG_TMR_INJECT)	+= xilinx_tmr_inject.o
+obj-$(CONFIG_TPS6594_ESM)	+= tps6594-esm.o
+obj-$(CONFIG_TPS6594_PFSM)	+= tps6594-pfsm.o
+obj-$(CONFIG_NSM)		+= nsm.o
+obj-$(CONFIG_MARVELL_CN10K_DPI)	+= mrvl_cn10k_dpi.o
+lan966x-pci-objs		:= lan966x_pci.o
+lan966x-pci-objs		+= lan966x_pci.dtbo.o
+obj-$(CONFIG_MCHP_LAN966X_PCI)	+= lan966x-pci.o
+obj-y				+= keba/
+obj-y				+= amd-sbi/
+obj-$(CONFIG_MISC_RP1)		+= rp1/
+obj-$(CONFIG_INTEL_SSEI)	+= issei/