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/arm64/boot/Makefile | 57 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) create mode 100644 arch/arm64/boot/Makefile (limited to 'arch/arm64/boot/Makefile') diff --git a/arch/arm64/boot/Makefile b/arch/arm64/boot/Makefile new file mode 100644 index 000000000..b5a08333b --- /dev/null +++ b/arch/arm64/boot/Makefile @@ -0,0 +1,57 @@ +# +# arch/arm64/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) 2012, ARM Ltd. +# Author: Will Deacon +# +# Based on the ia64 boot/Makefile. +# + +OBJCOPYFLAGS_Image :=-O binary -R .note -R .note.gnu.build-id -R .comment -S + +targets := Image Image.bz2 Image.gz Image.lz4 Image.lzma Image.lzo \ + Image.zst Image.xz image.fit + +$(obj)/Image: vmlinux FORCE + $(call if_changed,objcopy) + +$(obj)/Image.bz2: $(obj)/Image FORCE + $(call if_changed,bzip2) + +$(obj)/Image.gz: $(obj)/Image FORCE + $(call if_changed,gzip) + +$(obj)/Image.lz4: $(obj)/Image FORCE + $(call if_changed,lz4) + +$(obj)/Image.lzma: $(obj)/Image FORCE + $(call if_changed,lzma) + +$(obj)/Image.lzo: $(obj)/Image FORCE + $(call if_changed,lzo) + +$(obj)/Image.zst: $(obj)/Image FORCE + $(call if_changed,zstd) + +$(obj)/Image.xz: $(obj)/Image FORCE + $(call if_changed,xzkern) + +$(obj)/image.fit: $(obj)/Image $(obj)/dts/dtbs-list FORCE + $(call if_changed,fit) + +EFI_ZBOOT_PAYLOAD := Image +EFI_ZBOOT_BFD_TARGET := elf64-littleaarch64 +EFI_ZBOOT_MACH_TYPE := ARM64 +EFI_ZBOOT_FORWARD_CFI := $(CONFIG_ARM64_BTI_KERNEL) + +EFI_ZBOOT_OBJCOPY_FLAGS = --add-symbol zboot_code_size=0x$$( \ + $(NM) vmlinux|grep _kernel_codesize|cut -d' ' -f1) + +include $(srctree)/drivers/firmware/efi/libstub/Makefile.zboot -- cgit v1.3.1