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/media/rc/Makefile b/drivers/media/rc/Makefile
new file mode 100644
index 000000000..2bca6f7f0
--- /dev/null
+++ b/drivers/media/rc/Makefile
@@ -0,0 +1,56 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-y += keymaps/
+
+rc-core-y := rc-main.o rc-ir-raw.o
+rc-core-$(CONFIG_LIRC) += lirc_dev.o
+rc-core-$(CONFIG_MEDIA_CEC_RC) += keymaps/rc-cec.o
+rc-core-$(CONFIG_BPF_LIRC_MODE2) += bpf-lirc.o
+
+obj-$(CONFIG_RC_CORE) += rc-core.o
+
+# IR decoders - please keep it alphabetically sorted by Kconfig name
+# (e. g. LC_ALL=C sort Makefile)
+obj-$(CONFIG_IR_IMON_DECODER) += ir-imon-decoder.o
+obj-$(CONFIG_IR_JVC_DECODER) += ir-jvc-decoder.o
+obj-$(CONFIG_IR_MCE_KBD_DECODER) += ir-mce_kbd-decoder.o
+obj-$(CONFIG_IR_NEC_DECODER) += ir-nec-decoder.o
+obj-$(CONFIG_IR_RC5_DECODER) += ir-rc5-decoder.o
+obj-$(CONFIG_IR_RC6_DECODER) += ir-rc6-decoder.o
+obj-$(CONFIG_IR_RCMM_DECODER) += ir-rcmm-decoder.o
+obj-$(CONFIG_IR_SANYO_DECODER) += ir-sanyo-decoder.o
+obj-$(CONFIG_IR_SHARP_DECODER) += ir-sharp-decoder.o
+obj-$(CONFIG_IR_SONY_DECODER) += ir-sony-decoder.o
+obj-$(CONFIG_IR_XMP_DECODER) += ir-xmp-decoder.o
+
+# stand-alone IR receivers/transmitters  - please keep it alphabetically
+# sorted by Kconfig name (e. g. LC_ALL=C sort Makefile)
+obj-$(CONFIG_IR_ENE) += ene_ir.o
+obj-$(CONFIG_IR_FINTEK) += fintek-cir.o
+obj-$(CONFIG_IR_GPIO_CIR) += gpio-ir-recv.o
+obj-$(CONFIG_IR_GPIO_TX) += gpio-ir-tx.o
+obj-$(CONFIG_IR_HIX5HD2) += ir-hix5hd2.o
+obj-$(CONFIG_IR_IGORPLUGUSB) += igorplugusb.o
+obj-$(CONFIG_IR_IGUANA) += iguanair.o
+obj-$(CONFIG_IR_IMG) += img-ir/
+obj-$(CONFIG_IR_IMON) += imon.o
+obj-$(CONFIG_IR_IMON_RAW) += imon_raw.o
+obj-$(CONFIG_IR_ITE_CIR) += ite-cir.o
+obj-$(CONFIG_IR_MCEUSB) += mceusb.o
+obj-$(CONFIG_IR_MESON) += meson-ir.o
+obj-$(CONFIG_IR_MESON_TX) += meson-ir-tx.o
+obj-$(CONFIG_IR_MTK) += mtk-cir.o
+obj-$(CONFIG_IR_NUVOTON) += nuvoton-cir.o
+obj-$(CONFIG_IR_PWM_TX) += pwm-ir-tx.o
+obj-$(CONFIG_IR_REDRAT3) += redrat3.o
+obj-$(CONFIG_IR_SERIAL) += serial_ir.o
+obj-$(CONFIG_IR_SPI) += ir-spi.o
+obj-$(CONFIG_IR_STREAMZAP) += streamzap.o
+obj-$(CONFIG_IR_SUNXI) += sunxi-cir.o
+obj-$(CONFIG_IR_TOY) += ir_toy.o
+obj-$(CONFIG_IR_TTUSBIR) += ttusbir.o
+obj-$(CONFIG_IR_WINBOND_CIR) += winbond-cir.o
+obj-$(CONFIG_RC_ATI_REMOTE) += ati_remote.o
+obj-$(CONFIG_RC_LOOPBACK) += rc-loopback.o
+obj-$(CONFIG_RC_ST) += st_rc.o
+obj-$(CONFIG_RC_XBOX_DVD) += xbox_remote.o