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 --- scripts/package/debian/rules | 97 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 97 insertions(+) create mode 100755 scripts/package/debian/rules (limited to 'scripts/package/debian/rules') diff --git a/scripts/package/debian/rules b/scripts/package/debian/rules new file mode 100755 index 000000000..a417a7f8b --- /dev/null +++ b/scripts/package/debian/rules @@ -0,0 +1,97 @@ +#!/usr/bin/make -f +# SPDX-License-Identifier: GPL-2.0-only + +# in case debian/rules is executed directly +export DEB_RULES_REQUIRES_ROOT := no + +include debian/rules.vars + +ifneq (,$(filter-out parallel=1,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))) + NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS))) + MAKEFLAGS += -j$(NUMJOBS) +endif + +# When KBUILD_VERBOSE is undefined (presumably you are directly working with +# the debianized tree), show verbose logs unless DEB_BUILD_OPTION=terse is set. +ifeq ($(origin KBUILD_VERBOSE),undefined) + ifeq (,$(filter terse,$(DEB_BUILD_OPTIONS))) + export KBUILD_VERBOSE := 1 + else + Q := @ + endif +endif + +revision = $(shell dpkg-parsechangelog -S Version | sed -n 's/.*-//p') +CROSS_COMPILE ?= $(filter-out $(DEB_BUILD_GNU_TYPE)-, $(DEB_HOST_GNU_TYPE)-) +make-opts = ARCH=$(ARCH) KERNELRELEASE=$(KERNELRELEASE) \ + $(addprefix KBUILD_BUILD_VERSION=,$(revision)) \ + $(addprefix CROSS_COMPILE=,$(CROSS_COMPILE)) + +binary-targets := $(addprefix binary-, image image-dbg headers libc-dev) + +all-packages = $(shell dh_listpackages) +image-package = $(filter linux-image-% user-%, $(filter-out %-dbg, $(all-packages))) +image-dbg-package = $(filter %-dbg, $(all-packages)) +libc-dev-package = $(filter linux-libc-dev, $(all-packages)) +headers-package = $(filter linux-headers-%, $(all-packages)) + +mk-files = $(patsubst binary-%,debian/%.files,$1) +package = $($(@:binary-%=%-package)) + +# DH_OPTION is an environment variable common for all debhelper commands. +# We could 'export' it, but here it is passed from the command line to clarify +# which package is being processed in the build log. +DH_OPTIONS = -p$(package) + +# Note: future removal of KDEB_COMPRESS +# dpkg-deb >= 1.21.10 supports the DPKG_DEB_COMPRESSOR_TYPE environment +# variable, which provides the same functionality as KDEB_COMPRESS. The +# KDEB_COMPRESS variable will be removed in the future. +define binary + $(Q)dh_testdir $(DH_OPTIONS) + $(Q)dh_testroot $(DH_OPTIONS) + $(Q)dh_prep $(DH_OPTIONS) + $(Q)+$(MAKE) $(make-opts) run-command KBUILD_RUN_COMMAND='+$$(srctree)/scripts/package/builddeb $(package)' + $(Q)dh_installdocs $(DH_OPTIONS) + $(Q)dh_installchangelogs $(DH_OPTIONS) + $(Q)dh_compress $(DH_OPTIONS) + $(Q)dh_fixperms $(DH_OPTIONS) + $(Q)dh_gencontrol $(DH_OPTIONS) -- -f$(call mk-files,$@) + $(Q)dh_md5sums $(DH_OPTIONS) + $(Q)dh_builddeb $(DH_OPTIONS) -- $(addprefix -Z,$(KDEB_COMPRESS)) +endef + +.PHONY: $(binary-targets) +$(binary-targets): build-arch + $(Q)truncate -s0 $(call mk-files,$@) + $(if $(package),$(binary)) + +.PHONY: binary binary-indep binary-arch +binary: binary-arch binary-indep +binary-indep: build-indep +binary-arch: $(binary-targets) + $(Q)cat $(call mk-files,$^) > debian/files + +.PHONY: build build-indep build-arch +build: build-arch build-indep +build-indep: +build-arch: + $(Q)$(MAKE) $(make-opts) olddefconfig + $(Q)$(MAKE) $(make-opts) $(if $(filter um,$(ARCH)),,headers) all + +.PHONY: clean +clean: + $(Q)dh_clean + $(Q)rm -rf debian/deb-env.vars* debian/*.files + $(Q)$(MAKE) ARCH=$(ARCH) clean + +# If DEB_HOST_ARCH is empty, it is likely that debian/rules was executed +# directly. Run 'dpkg-architecture --print-set --print-format=make' to +# generate a makefile construct that exports all DEB_* variables. +ifndef DEB_HOST_ARCH +include debian/deb-env.vars + +debian/deb-env.vars: + $(Q)dpkg-architecture -a$$(cat debian/arch) --print-set --print-format=make > $@.tmp + $(Q)mv $@.tmp $@ +endif -- cgit v1.3.1