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/min-tool-version.sh | 49 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) create mode 100755 scripts/min-tool-version.sh (limited to 'scripts/min-tool-version.sh') diff --git a/scripts/min-tool-version.sh b/scripts/min-tool-version.sh new file mode 100755 index 000000000..99bfdcaa3 --- /dev/null +++ b/scripts/min-tool-version.sh @@ -0,0 +1,49 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0-only +# +# Print the minimum supported version of the given tool. +# When you raise the minimum version, please update +# Documentation/process/changes.rst as well. + +set -e + +if [ $# != 1 ]; then + echo "Usage: $0 toolname" >&2 + exit 1 +fi + +case "$1" in +binutils) + echo 2.30.0 + ;; +gcc) + if [ "$ARCH" = parisc64 ]; then + echo 12.0.0 + else + echo 8.1.0 + fi + ;; +llvm) + if [ "$SRCARCH" = loongarch ]; then + echo 18.0.0 + else + echo 17.0.1 + fi + ;; +rustc) + if [ "$SRCARCH" = "s390" ]; then + echo 1.96.0 + elif [ "$ARCH" = powerpc ]; then + echo 1.95.0 + else + echo 1.85.0 + fi + ;; +bindgen) + echo 0.71.1 + ;; +*) + echo "$1: unknown tool" >&2 + exit 1 + ;; +esac -- cgit v1.3.1