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/bridge/Makefile | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 net/bridge/Makefile (limited to 'net/bridge/Makefile') diff --git a/net/bridge/Makefile b/net/bridge/Makefile new file mode 100644 index 000000000..1203dc19e --- /dev/null +++ b/net/bridge/Makefile @@ -0,0 +1,37 @@ +# SPDX-License-Identifier: GPL-2.0 +# +# Makefile for the IEEE 802.1d ethernet bridging layer. +# + +obj-$(CONFIG_BRIDGE) += bridge.o + +bridge-y := br.o br_device.o br_fdb.o br_forward.o br_if.o br_input.o \ + br_ioctl.o br_stp.o br_stp_bpdu.o \ + br_stp_if.o br_stp_timer.o br_netlink.o \ + br_netlink_tunnel.o br_arp_nd_proxy.o + +bridge-$(CONFIG_SYSFS) += br_sysfs_if.o br_sysfs_br.o + +bridge-$(subst m,y,$(CONFIG_BRIDGE_NETFILTER)) += br_nf_core.o + +br_netfilter-y := br_netfilter_hooks.o +br_netfilter-$(subst m,y,$(CONFIG_IPV6)) += br_netfilter_ipv6.o +obj-$(CONFIG_BRIDGE_NETFILTER) += br_netfilter.o + +bridge-$(CONFIG_BRIDGE_IGMP_SNOOPING) += br_multicast.o br_mdb.o br_multicast_eht.o + +bridge-$(CONFIG_BRIDGE_VLAN_FILTERING) += br_vlan.o br_vlan_tunnel.o br_vlan_options.o br_mst.o + +bridge-$(CONFIG_NET_SWITCHDEV) += br_switchdev.o + +obj-$(CONFIG_NETFILTER) += netfilter/ + +bridge-$(CONFIG_BRIDGE_MRP) += br_mrp_switchdev.o br_mrp.o br_mrp_netlink.o + +bridge-$(CONFIG_BRIDGE_CFM) += br_cfm.o br_cfm_netlink.o + +ifdef CONFIG_GCOV_PROFILE_NETFILTER +GCOV_PROFILE_br_nf_core.o := y +GCOV_PROFILE_br_netfilter_hooks.o := y +GCOV_PROFILE_br_netfilter_ipv6.o := y +endif -- cgit v1.3.1