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 --- arch/arm/boot/Makefile | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 92 insertions(+) create mode 100644 arch/arm/boot/Makefile (limited to 'arch/arm/boot/Makefile') diff --git a/arch/arm/boot/Makefile b/arch/arm/boot/Makefile new file mode 100644 index 000000000..ba9b9a802 --- /dev/null +++ b/arch/arm/boot/Makefile @@ -0,0 +1,92 @@ +# +# arch/arm/boot/Makefile +# +# This file is included by the global makefile so that you can add your own +# architecture-specific flags and dependencies. +# +# This file is subject to the terms and conditions of the GNU General Public +# License. See the file "COPYING" in the main directory of this archive +# for more details. +# +# Copyright (C) 1995-2002 Russell King +# +OBJCOPYFLAGS :=-O binary -R .comment -S + +# ZRELADDR == virt_to_phys(PAGE_OFFSET + TEXT_OFFSET) +ifdef CONFIG_PHYS_OFFSET +add_hex = $(shell printf 0x%x $$(( $(1) + $(2) )) ) +ZRELADDR := $(call add_hex, $(CONFIG_PHYS_OFFSET), $(TEXT_OFFSET)) +endif + +PHYS_OFFSET := $(CONFIG_PHYS_OFFSET) +export ZRELADDR PARAMS_PHYS PHYS_OFFSET + +targets := Image zImage xipImage bootpImage uImage + +ifeq ($(CONFIG_XIP_KERNEL),y) + +cmd_deflate_xip_data = $(CONFIG_SHELL) -c '$(src)/deflate_xip_data.sh $< $@' + +ifeq ($(CONFIG_XIP_DEFLATED_DATA),y) +quiet_cmd_mkxip = XIPZ $@ +cmd_mkxip = $(cmd_objcopy) && $(cmd_deflate_xip_data) +else +quiet_cmd_mkxip = $(quiet_cmd_objcopy) +cmd_mkxip = $(cmd_objcopy) +endif + +$(obj)/xipImage: vmlinux FORCE + $(call if_changed,mkxip) + @$(kecho) ' Physical Address of xipImage: $(CONFIG_XIP_PHYS_ADDR)' + +$(obj)/Image $(obj)/zImage: FORCE + @echo 'Kernel configured for XIP (CONFIG_XIP_KERNEL=y)' + @echo 'Only the xipImage target is available in this case' + @false + +else + +$(obj)/xipImage: FORCE + @echo 'Kernel not configured for XIP (CONFIG_XIP_KERNEL!=y)' + @false + +$(obj)/Image: vmlinux FORCE + $(call if_changed,objcopy) + +$(obj)/compressed/vmlinux: $(obj)/Image FORCE + $(Q)$(MAKE) $(build)=$(obj)/compressed $@ + +$(obj)/zImage: $(obj)/compressed/vmlinux FORCE + $(call if_changed,objcopy) + +endif + +ifneq ($(LOADADDR),) + UIMAGE_LOADADDR=$(LOADADDR) +else + ifeq ($(CONFIG_ZBOOT_ROM),y) + UIMAGE_LOADADDR=$(CONFIG_ZBOOT_ROM_TEXT) + else + UIMAGE_LOADADDR=$(ZRELADDR) + endif +endif + +check_for_multiple_loadaddr = \ +if [ $(words $(UIMAGE_LOADADDR)) -ne 1 ]; then \ + echo 'multiple (or no) load addresses: $(UIMAGE_LOADADDR)'; \ + echo 'This is incompatible with uImages'; \ + echo 'Specify LOADADDR on the commandline to build an uImage'; \ + false; \ +fi + +$(obj)/uImage: $(obj)/zImage FORCE + @$(check_for_multiple_loadaddr) + $(call if_changed,uimage) + +$(obj)/bootp/bootp: $(obj)/zImage FORCE + $(Q)$(MAKE) $(build)=$(obj)/bootp $@ + +$(obj)/bootpImage: $(obj)/bootp/bootp FORCE + $(call if_changed,objcopy) + +subdir- := bootp compressed dts -- cgit v1.3.1