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 --- drivers/net/wireguard/device.h | 62 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) create mode 100644 drivers/net/wireguard/device.h (limited to 'drivers/net/wireguard/device.h') diff --git a/drivers/net/wireguard/device.h b/drivers/net/wireguard/device.h new file mode 100644 index 000000000..43c7cebbf --- /dev/null +++ b/drivers/net/wireguard/device.h @@ -0,0 +1,62 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2015-2019 Jason A. Donenfeld . All Rights Reserved. + */ + +#ifndef _WG_DEVICE_H +#define _WG_DEVICE_H + +#include "noise.h" +#include "allowedips.h" +#include "peerlookup.h" +#include "cookie.h" + +#include +#include +#include +#include +#include +#include + +struct wg_device; + +struct multicore_worker { + void *ptr; + struct work_struct work; +}; + +struct crypt_queue { + struct ptr_ring ring; + struct multicore_worker __percpu *worker; + int last_cpu; +}; + +struct prev_queue { + struct sk_buff *head, *tail, *peeked; + struct { struct sk_buff *next, *prev; } empty; // Match first 2 members of struct sk_buff. + atomic_t count; +}; + +struct wg_device { + struct net_device *dev; + struct crypt_queue encrypt_queue, decrypt_queue, handshake_queue; + struct sock __rcu *sock4, *sock6; + struct net __rcu *creating_net; + struct noise_static_identity static_identity; + struct workqueue_struct *packet_crypt_wq,*handshake_receive_wq, *handshake_send_wq; + struct cookie_checker cookie_checker; + struct pubkey_hashtable *peer_hashtable; + struct index_hashtable *index_hashtable; + struct allowedips peer_allowedips; + struct mutex device_update_lock, socket_update_lock; + struct list_head device_list, peer_list; + atomic_t handshake_queue_len; + unsigned int num_peers, device_update_gen; + u32 fwmark; + u16 incoming_port; +}; + +int wg_device_init(void); +void wg_device_uninit(void); + +#endif /* _WG_DEVICE_H */ -- cgit v1.3.1