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, 37 insertions, 0 deletions

diff --git a/drivers/pinctrl/freescale/Makefile b/drivers/pinctrl/freescale/Makefile
new file mode 100644
index 000000000..d27085c2b
--- /dev/null
+++ b/drivers/pinctrl/freescale/Makefile
@@ -0,0 +1,37 @@
+# SPDX-License-Identifier: GPL-2.0
+# Freescale pin control drivers
+obj-$(CONFIG_PINCTRL_IMX)	+= pinctrl-imx.o
+obj-$(CONFIG_PINCTRL_IMX_SCU)	+= pinctrl-scu.o
+obj-$(CONFIG_PINCTRL_IMX_SCMI)	+= pinctrl-imx-scmi.o
+obj-$(CONFIG_PINCTRL_IMX1_CORE)	+= pinctrl-imx1-core.o
+obj-$(CONFIG_PINCTRL_IMX1)	+= pinctrl-imx1.o
+obj-$(CONFIG_PINCTRL_IMX27)	+= pinctrl-imx27.o
+obj-$(CONFIG_PINCTRL_IMX35)	+= pinctrl-imx35.o
+obj-$(CONFIG_PINCTRL_IMX50)	+= pinctrl-imx50.o
+obj-$(CONFIG_PINCTRL_IMX51)	+= pinctrl-imx51.o
+obj-$(CONFIG_PINCTRL_IMX53)	+= pinctrl-imx53.o
+obj-$(CONFIG_PINCTRL_IMX6Q)	+= pinctrl-imx6q.o
+obj-$(CONFIG_PINCTRL_IMX6Q)	+= pinctrl-imx6dl.o
+obj-$(CONFIG_PINCTRL_IMX6SL)	+= pinctrl-imx6sl.o
+obj-$(CONFIG_PINCTRL_IMX6SLL)	+= pinctrl-imx6sll.o
+obj-$(CONFIG_PINCTRL_IMX6SX)	+= pinctrl-imx6sx.o
+obj-$(CONFIG_PINCTRL_IMX6UL)	+= pinctrl-imx6ul.o
+obj-$(CONFIG_PINCTRL_IMX7D)	+= pinctrl-imx7d.o
+obj-$(CONFIG_PINCTRL_IMX7ULP)	+= pinctrl-imx7ulp.o
+obj-$(CONFIG_PINCTRL_IMX8MM)	+= pinctrl-imx8mm.o
+obj-$(CONFIG_PINCTRL_IMX8MN)	+= pinctrl-imx8mn.o
+obj-$(CONFIG_PINCTRL_IMX8MP)	+= pinctrl-imx8mp.o
+obj-$(CONFIG_PINCTRL_IMX8MQ)	+= pinctrl-imx8mq.o
+obj-$(CONFIG_PINCTRL_IMX8QM)	+= pinctrl-imx8qm.o
+obj-$(CONFIG_PINCTRL_IMX8QXP)	+= pinctrl-imx8qxp.o
+obj-$(CONFIG_PINCTRL_IMX8DXL)	+= pinctrl-imx8dxl.o
+obj-$(CONFIG_PINCTRL_IMX8ULP)	+= pinctrl-imx8ulp.o
+obj-$(CONFIG_PINCTRL_IMX91)	+= pinctrl-imx91.o
+obj-$(CONFIG_PINCTRL_IMX93)	+= pinctrl-imx93.o
+obj-$(CONFIG_PINCTRL_VF610)	+= pinctrl-vf610.o
+obj-$(CONFIG_PINCTRL_MXS)	+= pinctrl-mxs.o
+obj-$(CONFIG_PINCTRL_IMX23)	+= pinctrl-imx23.o
+obj-$(CONFIG_PINCTRL_IMX25)	+= pinctrl-imx25.o
+obj-$(CONFIG_PINCTRL_IMX28)	+= pinctrl-imx28.o
+obj-$(CONFIG_PINCTRL_IMXRT1050)	+= pinctrl-imxrt1050.o
+obj-$(CONFIG_PINCTRL_IMXRT1170)	+= pinctrl-imxrt1170.o