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/mkspec | 97 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 97 insertions(+) create mode 100755 scripts/package/mkspec (limited to 'scripts/package/mkspec') diff --git a/scripts/package/mkspec b/scripts/package/mkspec new file mode 100755 index 000000000..c604f8c17 --- /dev/null +++ b/scripts/package/mkspec @@ -0,0 +1,97 @@ +#!/bin/sh +# +# Output a simple RPM spec file. +# This version assumes a minimum of RPM 4.13 +# +# The only gothic bit here is redefining install_post to avoid +# stripping the symbols from files in the kernel which we want +# +# Patched for non-x86 by Opencon (L) 2002 +# + +set -eu + +output=$1 + +mkdir -p "$(dirname "${output}")" + +exec >"${output}" + +if grep -q CONFIG_MODULES=y include/config/auto.conf; then +echo '%define with_devel %{?_without_devel: 0} %{?!_without_devel: 1}' +else +echo '%define with_devel 0' +fi + +# use %{debug_package} machinery to generate -debuginfo +with_debuginfo_rpm=0 +# manually generate -debuginfo package +with_debuginfo_manual=0 +# debuginfo package generation uses find-debuginfo.sh under the hood, +# which only works on uncompressed modules that contain debuginfo +if grep -q CONFIG_DEBUG_INFO=y include/config/auto.conf && + (! grep -q CONFIG_MODULE_COMPRESS=y include/config/auto.conf) && + (! grep -q CONFIG_DEBUG_INFO_SPLIT=y include/config/auto.conf); then + # If module signing is enabled (which may be required to boot with + # lockdown enabled), the find-debuginfo.sh machinery cannot be used + # because the signatures will be stripped off the modules. However, due + # to an rpm bug in versions prior to 4.20.0 + # + # https://github.com/rpm-software-management/rpm/issues/3057 + # https://github.com/rpm-software-management/rpm/commit/49f906998f3cf1f4152162ca61ac0869251c380f + # + # We cannot provide our own debuginfo package because it does not listen + # to our custom files list, failing the build due to unpackaged files. + # Manually generate the debug info package if using rpm 4.20.0. If not + # using rpm 4.20.0, avoid generating a -debuginfo package altogether, + # as it is not safe. + if grep -q CONFIG_MODULE_SIG=y include/config/auto.conf; then + rpm_ver_str=$(rpm --version 2>/dev/null) + # Split the version on spaces + IFS=' ' + set -- $rpm_ver_str + if [ "${1:-}" = RPM -a "${2:-}" = version ]; then + IFS=. + set -- $3 + rpm_ver=$(( 1000000 * $1 + 10000 * $2 + 100 * $3 + ${4:-0} )) + if [ "$rpm_ver" -ge 4200000 ]; then + with_debuginfo_manual='%{?_without_debuginfo:0}%{?!_without_debuginfo:1}' + fi + fi + else + with_debuginfo_rpm='%{?_without_debuginfo:0}%{?!_without_debuginfo:1}' + fi +fi +echo "%define with_debuginfo_manual $with_debuginfo_manual" +echo "%define with_debuginfo_rpm $with_debuginfo_rpm" + +cat</dev/null || hostname)} + builduser=${KBUILD_BUILD_USER:-$(id -nu)} + email="${builduser}@${buildhost}" +fi + +cat << EOF + +%changelog +* $(LC_ALL=C date +'%a %b %d %Y') ${name} <${email}> +- Custom built Linux kernel. +EOF -- cgit v1.3.1