GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog ============================================ WARNING: possible recursive locking detected 6.1.141-syzkaller #0 Not tainted -------------------------------------------- kworker/u4:1/11 is trying to acquire lock: ffff888072fc6218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff888072fc6218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3925 [inline] ffff888072fc6218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x208f/0x3760 net/core/dev.c:4300 but task is already holding lock: ffff888073c41258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] ffff888073c41258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline] ffff888073c41258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3882 [inline] ffff888073c41258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x129a/0x3760 net/core/dev.c:4300 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock); lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock); *** DEADLOCK *** May be due to missing lock nesting notation 8 locks held by kworker/u4:1/11: #0: ffff88807ac09938 ((wq_completion)bond1#3){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267 #1: ffffc90000107d00 ((work_completion)(&(&bond->alb_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267 #2: ffffffff8c92aaa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #2: ffffffff8c92aaa0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #2: ffffffff8c92aaa0 (rcu_read_lock){....}-{1:2}, at: bond_alb_monitor+0xee/0x17f0 drivers/net/bonding/bond_alb.c:1547 #3: ffffffff8c92aaa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #3: ffffffff8c92aaa0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #3: ffffffff8c92aaa0 (rcu_read_lock){....}-{1:2}, at: alb_send_learning_packets+0x116/0x2c0 drivers/net/bonding/bond_alb.c:1017 #4: ffffffff8c92ab00 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #4: ffffffff8c92ab00 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:843 [inline] #4: ffffffff8c92ab00 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x26f/0x3760 net/core/dev.c:4257 #5: ffff888073c41258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] #5: ffff888073c41258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline] #5: ffff888073c41258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3882 [inline] #5: ffff888073c41258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x129a/0x3760 net/core/dev.c:4300 #6: ffffffff8c92aaa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #6: ffffffff8c92aaa0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #6: ffffffff8c92aaa0 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x3e8/0x11b0 net/ipv4/ip_output.c:221 #7: ffffffff8c92ab00 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #7: ffffffff8c92ab00 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:843 [inline] #7: ffffffff8c92ab00 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x26f/0x3760 net/core/dev.c:4257 stack backtrace: CPU: 0 PID: 11 Comm: kworker/u4:1 Not tainted 6.1.141-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: bond1 bond_alb_monitor Call Trace: dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106 __lock_acquire+0x122f/0x7c50 kernel/locking/lockdep.c:-1 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] __dev_xmit_skb net/core/dev.c:3925 [inline] __dev_queue_xmit+0x208f/0x3760 net/core/dev.c:4300 dev_queue_xmit include/linux/netdevice.h:3051 [inline] neigh_hh_output include/net/neighbour.h:528 [inline] neigh_output include/net/neighbour.h:542 [inline] ip_finish_output2+0xbe8/0x11b0 net/ipv4/ip_output.c:228 iptunnel_xmit+0x525/0x930 net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x1c39/0x2360 net/ipv4/ip_tunnel.c:858 __gre_xmit net/ipv4/ip_gre.c:474 [inline] gre_tap_xmit+0x50b/0x700 net/ipv4/ip_gre.c:751 __netdev_start_xmit include/linux/netdevice.h:4896 [inline] netdev_start_xmit include/linux/netdevice.h:4910 [inline] xmit_one net/core/dev.c:3658 [inline] dev_hard_start_xmit+0x262/0x870 net/core/dev.c:3674 sch_direct_xmit+0x24e/0x4a0 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3895 [inline] __dev_queue_xmit+0x18cd/0x3760 net/core/dev.c:4300 alb_upper_dev_walk+0x212/0x3d0 drivers/net/bonding/bond_alb.c:-1 netdev_walk_all_upper_dev_rcu+0xf2/0x3d0 net/core/dev.c:7071 alb_send_learning_packets+0x1de/0x2c0 drivers/net/bonding/bond_alb.c:1018 bond_alb_monitor+0x3e1/0x17f0 drivers/net/bonding/bond_alb.c:1564 process_one_work+0x898/0x1160 kernel/workqueue.c:2292 worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog