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/install-extmod-build | 75 ++++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) create mode 100755 scripts/package/install-extmod-build (limited to 'scripts/package/install-extmod-build') diff --git a/scripts/package/install-extmod-build b/scripts/package/install-extmod-build new file mode 100755 index 000000000..f12e1ffe4 --- /dev/null +++ b/scripts/package/install-extmod-build @@ -0,0 +1,75 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0-only + +set -eu + +destdir=${1} + +is_enabled() { + grep -q "^$1=y" include/config/auto.conf +} + +find_in_scripts() { + find scripts \ + \( -name atomic -o -name dtc -o -name kconfig -o -name package \) -prune -o \ + ! -name unifdef -a ! -name mk_elfconfig -a \( -type f -o -type l \) -print +} + +mkdir -p "${destdir}" + +( + cd "${srctree}" + echo Makefile + find "arch/${SRCARCH}" -maxdepth 1 -name 'Makefile*' + find "arch/${SRCARCH}" -name generated -prune -o -name include -type d -print + find "arch/${SRCARCH}" -name Kbuild.platforms -o -name Platform + find include \( -name config -o -name generated \) -prune -o \( -type f -o -type l \) -print + find_in_scripts +) | tar -c -f - -C "${srctree}" -T - | tar -xf - -C "${destdir}" + +{ + if is_enabled CONFIG_OBJTOOL; then + echo tools/objtool/objtool + fi + + if is_enabled CONFIG_DEBUG_INFO_BTF_MODULES; then + echo tools/bpf/resolve_btfids/resolve_btfids + fi + + echo Module.symvers + echo "arch/${SRCARCH}/include/generated" + echo include/config/auto.conf + echo include/config/kernel.release + echo include/generated + find_in_scripts + + if is_enabled CONFIG_GCC_PLUGINS; then + find scripts/gcc-plugins -name '*.so' + fi +} | tar -c -f - -T - | tar -xf - -C "${destdir}" + +# When ${CC} and ${HOSTCC} differ, rebuild host programs using ${CC}. +# +# This caters to host programs that participate in Kbuild. objtool and +# resolve_btfids are out of scope. +if [ "${CC}" != "${HOSTCC}" ]; then + cat "${destdir}/scripts/Makefile" - <<-'EOF' > "${destdir}/scripts/Kbuild" + subdir-y += basic + hostprogs-always-y += mod/modpost + mod/modpost-objs := $(addprefix mod/, modpost.o file2alias.o sumversion.o symsearch.o) + EOF + + # HOSTCXX is not overridden. The C++ compiler is used to build: + # - scripts/kconfig/qconf, which is unneeded for external module builds + # - GCC plugins, which will not work on the installed system even after + # being rebuilt. + # + # Clear VPATH and srcroot because the source files reside in the output + # directory. + # shellcheck disable=SC2016 # $(MAKE) and $(build) will be expanded by Make + "${MAKE}" run-command KBUILD_RUN_COMMAND='+$(MAKE) HOSTCC="'"${CC}"'" VPATH= srcroot=. $(build)='"$(realpath --relative-to=. "${destdir}")"/scripts + + rm -f "${destdir}/scripts/Kbuild" +fi + +find "${destdir}" \( -name '.*.cmd' -o -name '*.o' \) -delete -- cgit v1.3.1