From 0d6526f82c3cdefcca47f73f5fc08dc6f335eac6 Mon Sep 17 00:00:00 2001 From: Tim Chen Date: Mon, 21 Sep 2026 17:37:22 -0700 Subject: sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling bug 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 Suggested-by: Chen Yu Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Kayra Cizmeci Cc: # v7.2.x Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com --- drivers/misc/mei/Makefile | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) create mode 100644 drivers/misc/mei/Makefile (limited to 'drivers/misc/mei/Makefile') diff --git a/drivers/misc/mei/Makefile b/drivers/misc/mei/Makefile new file mode 100644 index 000000000..9a6aa3359 --- /dev/null +++ b/drivers/misc/mei/Makefile @@ -0,0 +1,44 @@ +# SPDX-License-Identifier: GPL-2.0 +# +# Copyright (c) 2010-2019, Intel Corporation. All rights reserved. +# Makefile - Intel Management Engine Interface (Intel MEI) Linux driver +# +obj-$(CONFIG_INTEL_MEI) += mei.o +mei-objs := init.o +mei-objs += hbm.o +mei-objs += interrupt.o +mei-objs += client.o +mei-objs += main.o +mei-objs += dma-ring.o +mei-objs += bus.o +mei-objs += bus-fixup.o +mei-$(CONFIG_DEBUG_FS) += debugfs.o + +obj-$(CONFIG_INTEL_MEI_ME) += mei-me.o +mei-me-objs := pci-me.o +mei-me-objs += hw-me.o + +obj-$(CONFIG_INTEL_MEI_GSC) += mei-gsc.o +mei-gsc-objs := gsc-me.o + +obj-$(CONFIG_INTEL_MEI_CSC) += mei-csc.o +mei-csc-objs := pci-csc.o + +obj-$(CONFIG_INTEL_MEI_TXE) += mei-txe.o +mei-txe-objs := pci-txe.o +mei-txe-objs += hw-txe.o + +mei-$(CONFIG_EVENT_TRACING) += mei-trace.o +CFLAGS_mei-trace.o = -I$(src) + +obj-$(CONFIG_INTEL_MEI_HDCP) += hdcp/ +obj-$(CONFIG_INTEL_MEI_PXP) += pxp/ +obj-$(CONFIG_INTEL_MEI_GSC_PROXY) += gsc_proxy/ +obj-$(CONFIG_INTEL_MEI_LB) += mei_lb.o + +obj-$(CONFIG_INTEL_MEI_VSC_HW) += mei-vsc-hw.o +mei-vsc-hw-y := vsc-tp.o +mei-vsc-hw-y += vsc-fw-loader.o + +obj-$(CONFIG_INTEL_MEI_VSC) += mei-vsc.o +mei-vsc-y := platform-vsc.o -- cgit v1.3.1