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, 60 insertions, 0 deletions

diff --git a/drivers/clk/imx/Makefile b/drivers/clk/imx/Makefile
new file mode 100644
index 000000000..208b46873
--- /dev/null
+++ b/drivers/clk/imx/Makefile
@@ -0,0 +1,60 @@
+# SPDX-License-Identifier: GPL-2.0
+
+mxc-clk-objs += clk.o
+mxc-clk-objs += clk-busy.o
+mxc-clk-objs += clk-composite-7ulp.o
+mxc-clk-objs += clk-composite-8m.o
+mxc-clk-objs += clk-composite-93.o
+mxc-clk-objs += clk-fracn-gppll.o
+mxc-clk-objs += clk-cpu.o
+mxc-clk-objs += clk-divider-gate.o
+mxc-clk-objs += clk-fixup-div.o
+mxc-clk-objs += clk-fixup-mux.o
+mxc-clk-objs += clk-frac-pll.o
+mxc-clk-objs += clk-gate2.o
+mxc-clk-objs += clk-gate-93.o
+mxc-clk-objs += clk-gate-exclusive.o
+mxc-clk-objs += clk-pfd.o
+mxc-clk-objs += clk-pfdv2.o
+mxc-clk-objs += clk-pllv1.o
+mxc-clk-objs += clk-pllv2.o
+mxc-clk-objs += clk-pllv3.o
+mxc-clk-objs += clk-pllv4.o
+mxc-clk-objs += clk-pll14xx.o
+mxc-clk-objs += clk-sscg-pll.o
+mxc-clk-objs += clk-gpr-mux.o
+obj-$(CONFIG_MXC_CLK) += mxc-clk.o
+
+obj-$(CONFIG_CLK_IMX8MM) += clk-imx8mm.o
+obj-$(CONFIG_CLK_IMX8MN) += clk-imx8mn.o
+obj-$(CONFIG_CLK_IMX8MP) += clk-imx8mp.o clk-imx8mp-audiomix.o
+obj-$(CONFIG_CLK_IMX8MQ) += clk-imx8mq.o
+
+obj-$(CONFIG_CLK_IMX93) += clk-imx93.o
+obj-$(CONFIG_CLK_IMX95_BLK_CTL) += clk-imx95-blk-ctl.o
+
+obj-$(CONFIG_MXC_CLK_SCU) += clk-imx-scu.o clk-imx-lpcg-scu.o clk-imx-acm.o
+clk-imx-scu-$(CONFIG_CLK_IMX8QXP) += clk-scu.o clk-imx8qxp.o \
+				     clk-imx8qxp-rsrc.o clk-imx8qm-rsrc.o \
+				     clk-imx8dxl-rsrc.o
+clk-imx-lpcg-scu-$(CONFIG_CLK_IMX8QXP) += clk-lpcg-scu.o clk-imx8qxp-lpcg.o
+clk-imx-acm-$(CONFIG_CLK_IMX8QXP) = clk-imx8-acm.o
+
+obj-$(CONFIG_CLK_IMX8ULP) += clk-imx8ulp.o
+obj-$(CONFIG_CLK_IMX8ULP) += clk-imx8ulp-sim-lpav.o
+
+obj-$(CONFIG_CLK_IMX1)   += clk-imx1.o
+obj-$(CONFIG_CLK_IMX25)  += clk-imx25.o
+obj-$(CONFIG_CLK_IMX27)  += clk-imx27.o
+obj-$(CONFIG_CLK_IMX31)  += clk-imx31.o
+obj-$(CONFIG_CLK_IMX35)  += clk-imx35.o
+obj-$(CONFIG_CLK_IMX5)   += clk-imx5.o
+obj-$(CONFIG_CLK_IMX6Q)  += clk-imx6q.o
+obj-$(CONFIG_CLK_IMX6SL) += clk-imx6sl.o
+obj-$(CONFIG_CLK_IMX6SLL) += clk-imx6sll.o
+obj-$(CONFIG_CLK_IMX6SX) += clk-imx6sx.o
+obj-$(CONFIG_CLK_IMX6UL) += clk-imx6ul.o
+obj-$(CONFIG_CLK_IMX7D)  += clk-imx7d.o
+obj-$(CONFIG_CLK_IMX7ULP) += clk-imx7ulp.o
+obj-$(CONFIG_CLK_IMXRT1050)  += clk-imxrt1050.o
+obj-$(CONFIG_CLK_VF610)  += clk-vf610.o