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, 56 insertions, 0 deletions

diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
new file mode 100644
index 000000000..45ad17062
--- /dev/null
+++ b/drivers/reset/Makefile
@@ -0,0 +1,56 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-y += core.o
+obj-y += amlogic/
+obj-y += hisilicon/
+obj-y += spacemit/
+obj-y += starfive/
+obj-y += sti/
+obj-y += tegra/
+obj-$(CONFIG_RESET_A10SR) += reset-a10sr.o
+obj-$(CONFIG_RESET_ASPEED) += reset-aspeed.o
+obj-$(CONFIG_RESET_ATH79) += reset-ath79.o
+obj-$(CONFIG_RESET_AXS10X) += reset-axs10x.o
+obj-$(CONFIG_RESET_BCM6345) += reset-bcm6345.o
+obj-$(CONFIG_RESET_BERLIN) += reset-berlin.o
+obj-$(CONFIG_RESET_BRCMSTB) += reset-brcmstb.o
+obj-$(CONFIG_RESET_BRCMSTB_RESCAL) += reset-brcmstb-rescal.o
+obj-$(CONFIG_RESET_EIC7700) += reset-eic7700.o
+obj-$(CONFIG_RESET_EIC7700_HSP) += reset-eic7700-hsp.o
+obj-$(CONFIG_RESET_EYEQ) += reset-eyeq.o
+obj-$(CONFIG_RESET_GPIO) += reset-gpio.o
+obj-$(CONFIG_RESET_HSDK) += reset-hsdk.o
+obj-$(CONFIG_RESET_IMX_SCU) += reset-imx-scu.o
+obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
+obj-$(CONFIG_RESET_IMX8MP_AUDIOMIX) += reset-imx8mp-audiomix.o
+obj-$(CONFIG_RESET_INTEL_GW) += reset-intel-gw.o
+obj-$(CONFIG_RESET_K210) += reset-k210.o
+obj-$(CONFIG_RESET_K230) += reset-k230.o
+obj-$(CONFIG_RESET_LANTIQ) += reset-lantiq.o
+obj-$(CONFIG_RESET_LPC18XX) += reset-lpc18xx.o
+obj-$(CONFIG_RESET_MCHP_SPARX5) += reset-microchip-sparx5.o
+obj-$(CONFIG_RESET_NPCM) += reset-npcm.o
+obj-$(CONFIG_RESET_NUVOTON_MA35D1) += reset-ma35d1.o
+obj-$(CONFIG_RESET_PISTACHIO) += reset-pistachio.o
+obj-$(CONFIG_RESET_POLARFIRE_SOC) += reset-mpfs.o
+obj-$(CONFIG_RESET_QCOM_AOSS) += reset-qcom-aoss.o
+obj-$(CONFIG_RESET_QCOM_PDC) += reset-qcom-pdc.o
+obj-$(CONFIG_RESET_RASPBERRYPI) += reset-raspberrypi.o
+obj-$(CONFIG_RESET_RZG2L_USBPHY_CTRL) += reset-rzg2l-usbphy-ctrl.o
+obj-$(CONFIG_RESET_RZV2H_USB2PHY) += reset-rzv2h-usb2phy.o
+obj-$(CONFIG_RESET_SCMI) += reset-scmi.o
+obj-$(CONFIG_RESET_SIMPLE) += reset-simple.o
+obj-$(CONFIG_RESET_SKY1) += reset-sky1.o
+obj-$(CONFIG_RESET_SKY1_AUDSS) += reset-sky1-audss.o
+obj-$(CONFIG_RESET_SOCFPGA) += reset-socfpga.o
+obj-$(CONFIG_RESET_SUNPLUS) += reset-sunplus.o
+obj-$(CONFIG_RESET_SUNXI) += reset-sunxi.o
+obj-$(CONFIG_RESET_TENSTORRENT_ATLANTIS) += reset-tenstorrent-atlantis.o
+obj-$(CONFIG_RESET_TH1520) += reset-th1520.o
+obj-$(CONFIG_RESET_TI_SCI) += reset-ti-sci.o
+obj-$(CONFIG_RESET_TI_SYSCON) += reset-ti-syscon.o
+obj-$(CONFIG_RESET_TI_TPS380X) += reset-tps380x.o
+obj-$(CONFIG_RESET_TN48M_CPLD) += reset-tn48m.o
+obj-$(CONFIG_RESET_UNIPHIER) += reset-uniphier.o
+obj-$(CONFIG_RESET_UNIPHIER_GLUE) += reset-uniphier-glue.o
+obj-$(CONFIG_RESET_ZYNQ) += reset-zynq.o
+obj-$(CONFIG_RESET_ZYNQMP) += reset-zynqmp.o