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, 230 insertions, 0 deletions

diff --git a/drivers/pinctrl/bcm/Kconfig b/drivers/pinctrl/bcm/Kconfig
new file mode 100644
index 000000000..19d22e7fd
--- /dev/null
+++ b/drivers/pinctrl/bcm/Kconfig
@@ -0,0 +1,230 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Broadcom pinctrl drivers
+#
+
+config PINCTRL_BCM281XX
+	bool "Broadcom BCM281xx pinctrl driver"
+	depends on OF && (ARCH_BCM_MOBILE || COMPILE_TEST)
+	select PINMUX
+	select PINCONF
+	select GENERIC_PINCONF
+	select REGMAP_MMIO
+	default ARCH_BCM_MOBILE
+	help
+	  Say Y here to support Broadcom BCM281xx pinctrl driver, which is used
+	  for the BCM281xx SoC family, including BCM11130, BCM11140, BCM11351,
+	  BCM28145, and BCM28155 SoCs.  This driver requires the pinctrl
+	  framework.  GPIO is provided by a separate GPIO driver.
+
+config PINCTRL_BCM2835
+	tristate "Broadcom BCM2835 GPIO (with PINCONF) driver"
+	depends on OF && (ARCH_BCM2835 || ARCH_BRCMSTB || COMPILE_TEST)
+	select PINMUX
+	select PINCONF
+	select GENERIC_PINCONF
+	select GPIOLIB
+	select GPIOLIB_IRQCHIP
+	default ARCH_BCM2835 || ARCH_BRCMSTB
+	help
+	   Say Y here to enable the Broadcom BCM2835 GPIO driver.
+
+config PINCTRL_BCM4908
+	tristate "Broadcom BCM4908 pinmux driver"
+	depends on OF && (ARCH_BCMBCA || COMPILE_TEST)
+	select PINMUX
+	select PINCONF
+	select GENERIC_PINCONF
+	select GENERIC_PINCTRL_GROUPS
+	select GENERIC_PINMUX_FUNCTIONS
+	default ARCH_BCMBCA
+	help
+	  Driver for BCM4908 family SoCs with integrated pin controller.
+
+	  If compiled as module it will be called pinctrl-bcm4908.
+
+config PINCTRL_BCM63XX
+	bool
+	select PINMUX
+	select PINCONF
+	select GENERIC_PINCONF
+	select GPIOLIB
+	select REGMAP
+	select GPIO_REGMAP
+
+config PINCTRL_BCM6318
+	bool "Broadcom BCM6318 GPIO driver"
+	depends on (BMIPS_GENERIC || COMPILE_TEST)
+	depends on OF
+	select PINCTRL_BCM63XX
+	default BMIPS_GENERIC
+	help
+	   Say Y here to enable the Broadcom BCM6318 GPIO driver.
+
+config PINCTRL_BCM6328
+	bool "Broadcom BCM6328 GPIO driver"
+	depends on (BMIPS_GENERIC || COMPILE_TEST)
+	depends on OF
+	select PINCTRL_BCM63XX
+	default BMIPS_GENERIC
+	help
+	   Say Y here to enable the Broadcom BCM6328 GPIO driver.
+
+config PINCTRL_BCM6358
+	bool "Broadcom BCM6358 GPIO driver"
+	depends on (BMIPS_GENERIC || COMPILE_TEST)
+	depends on OF
+	select PINCTRL_BCM63XX
+	default BMIPS_GENERIC
+	help
+	   Say Y here to enable the Broadcom BCM6358 GPIO driver.
+
+config PINCTRL_BCM6362
+	bool "Broadcom BCM6362 GPIO driver"
+	depends on (BMIPS_GENERIC || COMPILE_TEST)
+	depends on OF
+	select PINCTRL_BCM63XX
+	default BMIPS_GENERIC
+	help
+	   Say Y here to enable the Broadcom BCM6362 GPIO driver.
+
+config PINCTRL_BCM6368
+	bool "Broadcom BCM6368 GPIO driver"
+	depends on (BMIPS_GENERIC || COMPILE_TEST)
+	depends on OF
+	select PINCTRL_BCM63XX
+	default BMIPS_GENERIC
+	help
+	   Say Y here to enable the Broadcom BCM6368 GPIO driver.
+
+config PINCTRL_BCM63268
+	bool "Broadcom BCM63268 GPIO driver"
+	depends on (BMIPS_GENERIC || COMPILE_TEST)
+	depends on OF
+	select PINCTRL_BCM63XX
+	default BMIPS_GENERIC
+	help
+	   Say Y here to enable the Broadcom BCM63268 GPIO driver.
+
+config PINCTRL_BRCMSTB
+        tristate "Broadcom STB product line pin controller driver"
+        depends on OF && (ARCH_BCM2835 || ARCH_BRCMSTB || COMPILE_TEST)
+        select PINMUX
+        select PINCONF
+        select GENERIC_PINCONF
+        help
+          Enable pin muxing and configuration functionality
+          for Broadcom STB product line chipsets.
+
+source "drivers/pinctrl/bcm/Kconfig.stb"
+
+config PINCTRL_IPROC_GPIO
+	bool "Broadcom iProc GPIO (with PINCONF) driver"
+	depends on ARCH_BCM_IPROC || COMPILE_TEST
+	select GPIOLIB
+	select GPIOLIB_IRQCHIP
+	select PINCONF
+	select GENERIC_PINCONF
+	default ARCH_BCM_IPROC
+	help
+	  Say yes here to enable the Broadcom iProc GPIO driver.
+
+	  The Broadcom iProc based SoCs- Cygnus, NS2, NSP and Stingray, use
+	  same GPIO Controller IP hence this driver could be used for all.
+
+	  The Broadcom Cygnus SoC has 3 GPIO controllers including the ASIU
+	  GPIO controller (ASIU), the chipCommonG GPIO controller (CCM), and
+	  the always-ON GPIO controller (CRMU/AON). All 3 GPIO controllers are
+	  supported by this driver.
+
+	  The Broadcom NSP has two GPIO controllers including the ChipcommonA
+	  GPIO, the ChipcommonB GPIO. Later controller is supported by this
+	  driver.
+
+	  The Broadcom NS2 has two GPIO controller including the CRMU GPIO,
+	  the ChipcommonG GPIO. Both controllers are supported by this driver.
+
+	  The Broadcom Stingray GPIO controllers are supported by this driver.
+
+	  All above SoCs GPIO controllers support basic PINCONF functions such
+	  as bias pull up, pull down, and drive strength configurations, when
+	  these pins are muxed to GPIO.
+
+	  It provides the framework where pins from the individual GPIO can be
+	  individually muxed to GPIO function, through interaction with the
+	  SoCs IOMUX controller. This features could be used only on SoCs which
+	  support individual pin muxing.
+
+config PINCTRL_CYGNUS_MUX
+	bool "Broadcom Cygnus IOMUX driver"
+	depends on (ARCH_BCM_CYGNUS || COMPILE_TEST)
+	depends on OF
+	select PINMUX
+	select GENERIC_PINCONF
+	default ARCH_BCM_CYGNUS
+	help
+	  Say yes here to enable the Broadcom Cygnus IOMUX driver.
+
+	  The Broadcom Cygnus IOMUX driver supports group based IOMUX
+	  configuration, with the exception that certain individual pins
+	  can be overridden to GPIO function
+
+config PINCTRL_NS
+	bool "Broadcom Northstar pins driver"
+	depends on OF && (ARCH_BCM_5301X || COMPILE_TEST)
+	select PINMUX
+	select GENERIC_PINCONF
+	select GENERIC_PINCTRL_GROUPS
+	select GENERIC_PINMUX_FUNCTIONS
+	default ARCH_BCM_5301X
+	help
+	  Say yes here to enable the Broadcom NS SoC pins driver.
+
+	  The Broadcom Northstar pins driver supports muxing multi-purpose pins
+	  that can be used for various functions (e.g. SPI, I2C, UART) as well
+	  as GPIOs.
+
+config PINCTRL_NSP_GPIO
+	bool "Broadcom NSP GPIO (with PINCONF) driver"
+	depends on ARCH_BCM_NSP || COMPILE_TEST
+	select GPIOLIB
+	select GPIOLIB_IRQCHIP
+	select PINCONF
+	select GENERIC_PINCONF
+	default ARCH_BCM_NSP
+	help
+	  Say yes here to enable the Broadcom NSP GPIO driver.
+
+	  The Broadcom Northstar Plus SoC ChipcommonA GPIO controller is
+	  supported by this driver.
+
+	  The ChipcommonA GPIO controller support basic PINCONF functions such
+	  as bias pull up, pull down, and drive strength configurations, when
+	  these pins are muxed to GPIO.
+
+config PINCTRL_NS2_MUX
+	bool "Broadcom Northstar2 pinmux driver"
+	depends on OF
+	depends on ARCH_BCM_IPROC || COMPILE_TEST
+	select PINMUX
+	select GENERIC_PINCONF
+	default ARM64 && ARCH_BCM_IPROC
+	help
+	  Say yes here to enable the Broadcom NS2 MUX driver.
+
+	  The Broadcom Northstar2 IOMUX driver supports group based IOMUX
+	  configuration.
+
+config PINCTRL_NSP_MUX
+	bool "Broadcom NSP IOMUX driver"
+	depends on (ARCH_BCM_NSP || COMPILE_TEST)
+	depends on OF
+	select PINMUX
+	select GENERIC_PINCONF
+	default ARCH_BCM_NSP
+	help
+	  Say yes here to enable the Broadcom NSP SOC IOMUX driver.
+
+	  The Broadcom Northstar Plus IOMUX driver supports pin based IOMUX
+	  configuration, with certain individual pins can be overridden
+	  to GPIO function.