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 --- net/mac80211/Makefile | 71 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 71 insertions(+) create mode 100644 net/mac80211/Makefile (limited to 'net/mac80211/Makefile') diff --git a/net/mac80211/Makefile b/net/mac80211/Makefile new file mode 100644 index 000000000..36f1e3e22 --- /dev/null +++ b/net/mac80211/Makefile @@ -0,0 +1,71 @@ +# SPDX-License-Identifier: GPL-2.0 +obj-$(CONFIG_MAC80211) += mac80211.o + +# mac80211 objects +mac80211-y := \ + main.o status.o \ + driver-ops.o \ + sta_info.o \ + wep.o \ + aead_api.o \ + wpa.o \ + scan.o offchannel.o \ + ht.o agg-tx.o agg-rx.o \ + vht.o \ + he.o \ + s1g.o \ + ibss.o \ + iface.o \ + link.o \ + rate.o \ + tkip.o \ + aes_cmac.o \ + aes_gmac.o \ + fils_aead.o \ + cfg.o \ + ethtool.o \ + rx.o \ + spectmgmt.o \ + tx.o \ + key.o \ + util.o parse.o \ + wme.o \ + chan.o ap.o \ + trace.o mlme.o \ + tdls.o \ + ocb.o \ + airtime.o \ + eht.o uhr.o nan.o + +mac80211-$(CONFIG_MAC80211_LEDS) += led.o +mac80211-$(CONFIG_MAC80211_DEBUGFS) += \ + debugfs.o \ + debugfs_sta.o \ + debugfs_netdev.o \ + debugfs_key.o + +mac80211-$(CONFIG_MAC80211_MESH) += \ + mesh.o \ + mesh_pathtbl.o \ + mesh_plink.o \ + mesh_hwmp.o \ + mesh_sync.o \ + mesh_ps.o + +mac80211-$(CONFIG_PM) += pm.o + +CFLAGS_trace.o := -I$(src) + +rc80211_minstrel-y := \ + rc80211_minstrel_ht.o + +rc80211_minstrel-$(CONFIG_MAC80211_DEBUGFS) += \ + rc80211_minstrel_ht_debugfs.o + +mac80211-$(CONFIG_MAC80211_RC_MINSTREL) += $(rc80211_minstrel-y) + +obj-y += tests/ + +mac80211-y += wbrf.o + +ccflags-y += -DDEBUG -- cgit v1.3.1