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/remove-stale-files | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) create mode 100755 scripts/remove-stale-files (limited to 'scripts/remove-stale-files') diff --git a/scripts/remove-stale-files b/scripts/remove-stale-files new file mode 100755 index 000000000..6e39fa854 --- /dev/null +++ b/scripts/remove-stale-files @@ -0,0 +1,28 @@ +#!/bin/sh + +set -e + +# When you move, remove or rename generated files, you probably also update +# .gitignore and cleaning rules in the Makefile. This is the right thing +# to do. However, people usually do 'git pull', 'git bisect', etc. without +# running 'make clean'. Then, the stale generated files are left over, often +# causing build issues. +# +# Also, 'git status' shows such stale build artifacts as untracked files. +# What is worse, some people send a wrong patch to get them back to .gitignore +# without checking the commit history. +# +# So, when you (re)move generated files, please move the cleaning rules from +# the Makefile to this script. This is run before Kbuild starts building +# anything, so people will not be annoyed by such garbage files. +# +# This script is not intended to grow endlessly. Rather, it is a temporary scrap +# yard. Stale files stay in this file for a while (for some release cycles?), +# then will be really dead and removed from the code base entirely. + +# moved to security/selinux/genheaders +rm -f scripts/selinux/genheaders/genheaders + +rm -f *.spec + +rm -f lib/test_fortify.log -- cgit v1.3.1