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, 63 insertions, 0 deletions

diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
new file mode 100644
index 000000000..6f5798b27
--- /dev/null
+++ b/drivers/fpga/Makefile
@@ -0,0 +1,63 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the fpga framework and fpga manager drivers.
+#
+
+# Core FPGA Manager Framework
+obj-$(CONFIG_FPGA)			+= fpga-mgr.o
+
+# FPGA Manager Drivers
+obj-$(CONFIG_FPGA_MGR_ALTERA_CVP)	+= altera-cvp.o
+obj-$(CONFIG_FPGA_MGR_ALTERA_PS_SPI)	+= altera-ps-spi.o
+obj-$(CONFIG_FPGA_MGR_ICE40_SPI)	+= ice40-spi.o
+obj-$(CONFIG_FPGA_MGR_MACHXO2_SPI)	+= machxo2-spi.o
+obj-$(CONFIG_FPGA_MGR_SOCFPGA)		+= socfpga.o
+obj-$(CONFIG_FPGA_MGR_SOCFPGA_A10)	+= socfpga-a10.o
+obj-$(CONFIG_FPGA_MGR_STRATIX10_SOC)	+= stratix10-soc.o
+obj-$(CONFIG_FPGA_MGR_TS73XX)		+= ts73xx-fpga.o
+obj-$(CONFIG_FPGA_MGR_XILINX_CORE)	+= xilinx-core.o
+obj-$(CONFIG_FPGA_MGR_XILINX_SELECTMAP)	+= xilinx-selectmap.o
+obj-$(CONFIG_FPGA_MGR_XILINX_SPI)	+= xilinx-spi.o
+obj-$(CONFIG_FPGA_MGR_ZYNQ_FPGA)	+= zynq-fpga.o
+obj-$(CONFIG_FPGA_MGR_ZYNQMP_FPGA)	+= zynqmp-fpga.o
+obj-$(CONFIG_FPGA_MGR_VERSAL_FPGA)	+= versal-fpga.o
+obj-$(CONFIG_FPGA_MGR_MICROCHIP_SPI)	+= microchip-spi.o
+obj-$(CONFIG_FPGA_MGR_LATTICE_SYSCONFIG)	+= lattice-sysconfig.o
+obj-$(CONFIG_FPGA_MGR_LATTICE_SYSCONFIG_SPI)	+= lattice-sysconfig-spi.o
+obj-$(CONFIG_ALTERA_PR_IP_CORE)		+= altera-pr-ip-core.o
+obj-$(CONFIG_ALTERA_PR_IP_CORE_PLAT)	+= altera-pr-ip-core-plat.o
+obj-$(CONFIG_FPGA_MGR_EFINIX_SPI)	+= efinix-spi.o
+
+# FPGA Secure Update Drivers
+obj-$(CONFIG_FPGA_M10_BMC_SEC_UPDATE)	+= intel-m10-bmc-sec-update.o
+
+# FPGA Bridge Drivers
+obj-$(CONFIG_FPGA_BRIDGE)		+= fpga-bridge.o
+obj-$(CONFIG_SOCFPGA_FPGA_BRIDGE)	+= altera-hps2fpga.o altera-fpga2sdram.o
+obj-$(CONFIG_ALTERA_FREEZE_BRIDGE)	+= altera-freeze-bridge.o
+obj-$(CONFIG_XILINX_PR_DECOUPLER)	+= xilinx-pr-decoupler.o
+
+# High Level Interfaces
+obj-$(CONFIG_FPGA_REGION)		+= fpga-region.o
+obj-$(CONFIG_OF_FPGA_REGION)		+= of-fpga-region.o
+
+# FPGA Device Feature List Support
+obj-$(CONFIG_FPGA_DFL)			+= dfl.o
+obj-$(CONFIG_FPGA_DFL_FME)		+= dfl-fme.o
+obj-$(CONFIG_FPGA_DFL_FME_MGR)		+= dfl-fme-mgr.o
+obj-$(CONFIG_FPGA_DFL_FME_BRIDGE)	+= dfl-fme-br.o
+obj-$(CONFIG_FPGA_DFL_FME_REGION)	+= dfl-fme-region.o
+obj-$(CONFIG_FPGA_DFL_AFU)		+= dfl-afu.o
+
+dfl-fme-objs := dfl-fme-main.o dfl-fme-pr.o dfl-fme-error.o
+dfl-fme-objs += dfl-fme-perf.o
+dfl-afu-objs := dfl-afu-main.o dfl-afu-region.o dfl-afu-dma-region.o
+dfl-afu-objs += dfl-afu-error.o
+
+obj-$(CONFIG_FPGA_DFL_NIOS_INTEL_PAC_N3000)	+= dfl-n3000-nios.o
+
+# Drivers for FPGAs which implement DFL
+obj-$(CONFIG_FPGA_DFL_PCI)		+= dfl-pci.o
+
+# KUnit tests
+obj-$(CONFIG_FPGA_KUNIT_TESTS)		+= tests/