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/Makefile.headersinst | 84 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 84 insertions(+) create mode 100644 scripts/Makefile.headersinst (limited to 'scripts/Makefile.headersinst') diff --git a/scripts/Makefile.headersinst b/scripts/Makefile.headersinst new file mode 100644 index 000000000..029d85bb0 --- /dev/null +++ b/scripts/Makefile.headersinst @@ -0,0 +1,84 @@ +# SPDX-License-Identifier: GPL-2.0 +# ========================================================================== +# Installing headers +# +# All headers under include/uapi, include/generated/uapi, +# arch//include/uapi and arch//include/generated/uapi are +# exported. +# They are preprocessed to remove __KERNEL__ section of the file. +# +# ========================================================================== + +PHONY := __headers +__headers: + +include $(srctree)/scripts/Kbuild.include + +src := $(srctree)/$(obj) +gen := $(objtree)/$(subst include/,include/generated/,$(obj)) +dst := usr/include + +-include $(src)/Kbuild + +# $(filter %/, ...) is a workaround for GNU Make <= 4.2.1, where +# $(wildcard $(src)/*/) contains not only directories but also regular files. +src-subdirs := $(patsubst $(src)/%/,%,$(filter %/, $(wildcard $(src)/*/))) +gen-subdirs := $(patsubst $(gen)/%/,%,$(filter %/, $(wildcard $(gen)/*/))) +all-subdirs := $(sort $(src-subdirs) $(gen-subdirs)) + +src-headers := $(if $(src-subdirs), $(shell cd $(src) && find $(src-subdirs) -name '*.h')) +src-headers := $(filter-out $(no-export-headers), $(src-headers)) +gen-headers := $(if $(gen-subdirs), $(shell cd $(gen) && find $(gen-subdirs) -name '*.h')) +gen-headers := $(filter-out $(no-export-headers), $(gen-headers)) + +# If the same header is exported from source and generated directories, +# the former takes precedence, but this should be warned. +duplicated := $(filter $(gen-headers), $(src-headers)) +$(if $(duplicated), $(warning duplicated header export: $(duplicated))) + +gen-headers := $(filter-out $(duplicated), $(gen-headers)) + +# Add dst path prefix +all-subdirs := $(addprefix $(dst)/, $(all-subdirs)) +src-headers := $(addprefix $(dst)/, $(src-headers)) +gen-headers := $(addprefix $(dst)/, $(gen-headers)) +all-headers := $(src-headers) $(gen-headers) + +# Work out what needs to be removed +old-subdirs := $(wildcard $(all-subdirs)) +old-headers := $(if $(old-subdirs),$(shell find $(old-subdirs) -name '*.h')) +unwanted := $(filter-out $(all-headers), $(old-headers)) + +# Create directories +existing-dirs := $(sort $(dir $(old-headers))) +wanted-dirs := $(sort $(dir $(all-headers))) +new-dirs := $(filter-out $(existing-dirs), $(wanted-dirs)) +$(if $(new-dirs), $(shell mkdir -p $(new-dirs))) + +# Rules +quiet_cmd_install = HDRINST $@ + cmd_install = $(CONFIG_SHELL) $(srctree)/scripts/headers_install.sh $< $@ + +$(src-headers): $(dst)/%.h: $(src)/%.h $(srctree)/scripts/headers_install.sh FORCE + $(call if_changed,install) + +$(gen-headers): $(dst)/%.h: $(gen)/%.h $(srctree)/scripts/headers_install.sh FORCE + $(call if_changed,install) + +quiet_cmd_remove = REMOVE $(unwanted) + cmd_remove = rm -f $(unwanted) + +__headers: $(all-headers) +ifneq ($(unwanted),) + $(call cmd,remove) +endif + @: + +existing-headers := $(filter $(old-headers), $(all-headers)) + +-include $(foreach f,$(existing-headers),$(dir $(f)).$(notdir $(f)).cmd) + +PHONY += FORCE +FORCE: + +.PHONY: $(PHONY) -- cgit v1.3.1