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/Makefile | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 77 insertions(+) create mode 100644 net/Makefile (limited to 'net/Makefile') diff --git a/net/Makefile b/net/Makefile new file mode 100644 index 000000000..5b2dd7f07 --- /dev/null +++ b/net/Makefile @@ -0,0 +1,77 @@ +# SPDX-License-Identifier: GPL-2.0 +# +# Makefile for the linux networking. +# +# 2 Sep 2000, Christoph Hellwig +# Rewritten to use lists instead of if-statements. +# + +obj-y := devres.o socket.o core/ + +obj-$(CONFIG_COMPAT) += compat.o + +# LLC has to be linked before the files in net/802/ +obj-$(CONFIG_LLC) += llc/ +obj-y += ethernet/ 802/ sched/ netlink/ bpf/ ethtool/ +obj-$(CONFIG_NETFILTER) += netfilter/ +obj-$(CONFIG_INET) += ipv4/ +obj-$(CONFIG_TLS) += tls/ +obj-$(CONFIG_XFRM) += xfrm/ +obj-$(CONFIG_UNIX) += unix/ +obj-$(CONFIG_INET_PSP) += psp/ +obj-y += ipv6/ +obj-$(CONFIG_PACKET) += packet/ +obj-$(CONFIG_NET_KEY) += key/ +obj-$(CONFIG_BRIDGE) += bridge/ +obj-$(CONFIG_NET_DEVLINK) += devlink/ +obj-y += dsa/ +obj-$(CONFIG_X25) += x25/ +obj-$(CONFIG_LAPB) += lapb/ +obj-$(CONFIG_CAN) += can/ +obj-$(CONFIG_BT) += bluetooth/ +obj-$(CONFIG_SUNRPC) += sunrpc/ +obj-$(CONFIG_AF_RXRPC) += rxrpc/ +obj-$(CONFIG_AF_KCM) += kcm/ +obj-$(CONFIG_STREAM_PARSER) += strparser/ +obj-$(CONFIG_ATM) += atm/ +obj-$(CONFIG_L2TP) += l2tp/ +obj-$(CONFIG_PHONET) += phonet/ +ifneq ($(CONFIG_VLAN_8021Q),) +obj-y += 8021q/ +endif +obj-$(CONFIG_IP_SCTP) += sctp/ +obj-$(CONFIG_RDS) += rds/ +obj-$(CONFIG_WIRELESS) += wireless/ +obj-$(CONFIG_MAC80211) += mac80211/ +obj-$(CONFIG_TIPC) += tipc/ +obj-$(CONFIG_NETLABEL) += netlabel/ +obj-$(CONFIG_IUCV) += iucv/ +obj-$(CONFIG_SMC) += smc/ +obj-$(CONFIG_RFKILL) += rfkill/ +obj-$(CONFIG_NET_9P) += 9p/ +obj-$(CONFIG_DCB) += dcb/ +obj-$(CONFIG_6LOWPAN) += 6lowpan/ +obj-$(CONFIG_IEEE802154) += ieee802154/ +obj-$(CONFIG_MAC802154) += mac802154/ + +obj-$(CONFIG_SYSCTL) += sysctl_net.o +obj-$(CONFIG_DNS_RESOLVER) += dns_resolver/ +obj-$(CONFIG_CEPH_LIB) += ceph/ +obj-$(CONFIG_BATMAN_ADV) += batman-adv/ +obj-$(CONFIG_NFC) += nfc/ +obj-$(CONFIG_PSAMPLE) += psample/ +obj-$(CONFIG_NET_IFE) += ife/ +obj-$(CONFIG_OPENVSWITCH) += openvswitch/ +obj-$(CONFIG_VSOCKETS) += vmw_vsock/ +obj-$(CONFIG_MPLS) += mpls/ +obj-$(CONFIG_NET_NSH) += nsh/ +obj-$(CONFIG_HSR) += hsr/ +obj-$(CONFIG_NET_SWITCHDEV) += switchdev/ +obj-$(CONFIG_NET_L3_MASTER_DEV) += l3mdev/ +obj-$(CONFIG_QRTR) += qrtr/ +obj-$(CONFIG_NET_NCSI) += ncsi/ +obj-$(CONFIG_XDP_SOCKETS) += xdp/ +obj-$(CONFIG_MPTCP) += mptcp/ +obj-$(CONFIG_MCTP) += mctp/ +obj-$(CONFIG_NET_HANDSHAKE) += handshake/ +obj-$(CONFIG_NET_SHAPER) += shaper/ -- cgit v1.3.1