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/wireless/ap.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) create mode 100644 net/wireless/ap.c (limited to 'net/wireless/ap.c') diff --git a/net/wireless/ap.c b/net/wireless/ap.c new file mode 100644 index 000000000..9a9a87080 --- /dev/null +++ b/net/wireless/ap.c @@ -0,0 +1,74 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Parts of this file are + * Copyright (C) 2022-2023 Intel Corporation + */ +#include +#include +#include +#include "nl80211.h" +#include "core.h" +#include "rdev-ops.h" + + +static int ___cfg80211_stop_ap(struct cfg80211_registered_device *rdev, + struct net_device *dev, unsigned int link_id, + bool notify) +{ + struct wireless_dev *wdev = dev->ieee80211_ptr; + int err; + + lockdep_assert_wiphy(wdev->wiphy); + + if (!rdev->ops->stop_ap) + return -EOPNOTSUPP; + + if (dev->ieee80211_ptr->iftype != NL80211_IFTYPE_AP && + dev->ieee80211_ptr->iftype != NL80211_IFTYPE_P2P_GO) + return -EOPNOTSUPP; + + if (!wdev->links[link_id].ap.beacon_interval) + return -ENOENT; + + err = rdev_stop_ap(rdev, dev, link_id); + if (!err) { + wdev->conn_owner_nlportid = 0; + wdev->links[link_id].ap.beacon_interval = 0; + memset(&wdev->links[link_id].ap.chandef, 0, + sizeof(wdev->links[link_id].ap.chandef)); + wdev->u.ap.ssid_len = 0; + rdev_set_qos_map(rdev, dev, NULL); + if (notify) + nl80211_send_ap_stopped(wdev, link_id); + + /* Should we apply the grace period during beaconing interface + * shutdown also? + */ + cfg80211_sched_dfs_chan_update(rdev); + } + + schedule_work(&cfg80211_disconnect_work); + + return err; +} + +int cfg80211_stop_ap(struct cfg80211_registered_device *rdev, + struct net_device *dev, int link_id, + bool notify) +{ + unsigned int link; + int ret = 0; + + if (link_id >= 0) + return ___cfg80211_stop_ap(rdev, dev, link_id, notify); + + for_each_valid_link(dev->ieee80211_ptr, link) { + int ret1 = ___cfg80211_stop_ap(rdev, dev, link, notify); + + if (ret1) + ret = ret1; + /* try the next one also if one errored */ + } + + return ret; +} -- cgit v1.3.1