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, 103 insertions, 0 deletions

diff --git a/drivers/pinctrl/Makefile b/drivers/pinctrl/Makefile
new file mode 100644
index 000000000..a35d71135
--- /dev/null
+++ b/drivers/pinctrl/Makefile
@@ -0,0 +1,103 @@
+# SPDX-License-Identifier: GPL-2.0
+# generic pinmux support
+
+subdir-ccflags-$(CONFIG_DEBUG_PINCTRL)	+= -DDEBUG
+
+obj-y				+= core.o pinctrl-utils.o
+obj-$(CONFIG_PINMUX)		+= pinmux.o
+obj-$(CONFIG_PINCONF)		+= pinconf.o
+obj-$(CONFIG_GENERIC_PINCONF)	+= pinconf-generic.o
+obj-$(CONFIG_GENERIC_PINCTRL)	+= pinctrl-generic.o
+obj-$(CONFIG_OF)		+= devicetree.o
+
+obj-$(CONFIG_PINCTRL_AMD)	+= pinctrl-amd.o
+obj-$(CONFIG_PINCTRL_AMDISP)	+= pinctrl-amdisp.o
+obj-$(CONFIG_PINCTRL_APPLE_GPIO) += pinctrl-apple-gpio.o
+obj-$(CONFIG_PINCTRL_ARTPEC6)	+= pinctrl-artpec6.o
+obj-$(CONFIG_PINCTRL_AS3722)	+= pinctrl-as3722.o
+obj-$(CONFIG_PINCTRL_AT91)	+= pinctrl-at91.o
+obj-$(CONFIG_PINCTRL_AT91PIO4)	+= pinctrl-at91-pio4.o
+obj-$(CONFIG_PINCTRL_AW9523)	+= pinctrl-aw9523.o
+obj-$(CONFIG_PINCTRL_AXP209)	+= pinctrl-axp209.o
+obj-$(CONFIG_PINCTRL_BM1880)	+= pinctrl-bm1880.o
+obj-$(CONFIG_PINCTRL_CY8C95X0)	+= pinctrl-cy8c95x0.o
+obj-$(CONFIG_PINCTRL_DA850_PUPD) += pinctrl-da850-pupd.o
+obj-$(CONFIG_PINCTRL_DA9062)	+= pinctrl-da9062.o
+obj-$(CONFIG_PINCTRL_DIGICOLOR)	+= pinctrl-digicolor.o
+obj-$(CONFIG_PINCTRL_EIC7700)	+= pinctrl-eic7700.o
+obj-$(CONFIG_PINCTRL_EQUILIBRIUM)   += pinctrl-equilibrium.o
+obj-$(CONFIG_PINCTRL_EP93XX)	+= pinctrl-ep93xx.o
+obj-$(CONFIG_PINCTRL_EYEQ5)	+= pinctrl-eyeq5.o
+obj-$(CONFIG_PINCTRL_GEMINI)	+= pinctrl-gemini.o
+obj-$(CONFIG_PINCTRL_GENERIC_MUX) += pinctrl-generic-mux.o
+obj-$(CONFIG_PINCTRL_INGENIC)	+= pinctrl-ingenic.o
+obj-$(CONFIG_PINCTRL_K210)	+= pinctrl-k210.o
+obj-$(CONFIG_PINCTRL_K230)	+= pinctrl-k230.o
+obj-$(CONFIG_PINCTRL_KEEMBAY)	+= pinctrl-keembay.o
+obj-$(CONFIG_PINCTRL_LANTIQ)	+= pinctrl-lantiq.o
+obj-$(CONFIG_PINCTRL_FALCON)	+= pinctrl-falcon.o
+obj-$(CONFIG_PINCTRL_LOONGSON2) += pinctrl-loongson2.o
+obj-$(CONFIG_PINCTRL_XWAY)	+= pinctrl-xway.o
+obj-$(CONFIG_PINCTRL_LPC18XX)	+= pinctrl-lpc18xx.o
+obj-$(CONFIG_PINCTRL_MAX7360)	+= pinctrl-max7360.o
+obj-$(CONFIG_PINCTRL_MAX77620)	+= pinctrl-max77620.o
+obj-$(CONFIG_PINCTRL_MCP23S08_I2C)	+= pinctrl-mcp23s08_i2c.o
+obj-$(CONFIG_PINCTRL_MCP23S08_SPI)	+= pinctrl-mcp23s08_spi.o
+obj-$(CONFIG_PINCTRL_MCP23S08)	+= pinctrl-mcp23s08.o
+obj-$(CONFIG_PINCTRL_MICROCHIP_SGPIO)	+= pinctrl-microchip-sgpio.o
+obj-$(CONFIG_PINCTRL_MLXBF3)	+= pinctrl-mlxbf3.o
+obj-$(CONFIG_PINCTRL_OCELOT)	+= pinctrl-ocelot.o
+obj-$(CONFIG_PINCTRL_PALMAS)	+= pinctrl-palmas.o
+obj-$(CONFIG_PINCTRL_PEF2256)	+= pinctrl-pef2256.o
+obj-$(CONFIG_PINCTRL_PIC32)	+= pinctrl-pic32.o
+obj-$(CONFIG_PINCTRL_PISTACHIO)	+= pinctrl-pistachio.o
+obj-$(CONFIG_PINCTRL_RK805)	+= pinctrl-rk805.o
+obj-$(CONFIG_PINCTRL_ROCKCHIP)	+= pinctrl-rockchip.o
+obj-$(CONFIG_PINCTRL_RP1)       += pinctrl-rp1.o
+obj-$(CONFIG_PINCTRL_SCMI)	+= pinctrl-scmi.o
+obj-$(CONFIG_PINCTRL_SINGLE)	+= pinctrl-single.o
+obj-$(CONFIG_PINCTRL_ST) 	+= pinctrl-st.o
+obj-$(CONFIG_PINCTRL_STMFX) 	+= pinctrl-stmfx.o
+obj-$(CONFIG_PINCTRL_SX150X)	+= pinctrl-sx150x.o
+obj-$(CONFIG_PINCTRL_TB10X)	+= pinctrl-tb10x.o
+obj-$(CONFIG_PINCTRL_TPS6594)	+= pinctrl-tps6594.o
+obj-$(CONFIG_PINCTRL_TH1520)	+= pinctrl-th1520.o
+obj-$(CONFIG_PINCTRL_UPBOARD)	+= pinctrl-upboard.o
+obj-$(CONFIG_PINCTRL_ZYNQMP)	+= pinctrl-zynqmp.o
+obj-$(CONFIG_PINCTRL_ZYNQ)	+= pinctrl-zynq.o
+
+obj-y				+= actions/
+obj-y				+= airoha/
+obj-$(CONFIG_PINCTRL_ASPEED)	+= aspeed/
+obj-y				+= bcm/
+obj-$(CONFIG_PINCTRL_BERLIN)	+= berlin/
+obj-y				+= cirrus/
+obj-y				+= cix/
+obj-y				+= freescale/
+obj-$(CONFIG_X86)		+= intel/
+obj-y				+= mediatek/
+obj-$(CONFIG_PINCTRL_MESON)	+= meson/
+obj-y				+= microchip/
+obj-y				+= mvebu/
+obj-y				+= nomadik/
+obj-y				+= nuvoton/
+obj-y				+= nxp/
+obj-$(CONFIG_PINCTRL_PXA)	+= pxa/
+obj-y				+= qcom/
+obj-$(CONFIG_PINCTRL_RTD)	+= realtek/
+obj-$(CONFIG_PINCTRL_RENESAS)	+= renesas/
+obj-$(CONFIG_PINCTRL_SAMSUNG)	+= samsung/
+obj-y				+= sophgo/
+obj-y				+= spacemit/
+obj-$(CONFIG_PINCTRL_SPEAR)	+= spear/
+obj-y				+= sprd/
+obj-y				+= starfive/
+obj-$(CONFIG_PINCTRL_STM32)	+= stm32/
+obj-y				+= sunplus/
+obj-$(CONFIG_PINCTRL_SUNXI)	+= sunxi/
+obj-y				+= tegra/
+obj-y				+= ti/
+obj-$(CONFIG_PINCTRL_ULTRARISC)	+= ultrarisc/
+obj-$(CONFIG_PINCTRL_UNIPHIER)	+= uniphier/
+obj-$(CONFIG_PINCTRL_VISCONTI)	+= visconti/
+obj-$(CONFIG_PINCTRL_WMT)	+= vt8500/