============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- kworker/0:5/5732 is trying to acquire lock: ffff88804f87a158 (&qdisc_xmit_lock_key#3){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:347 [inline] ffff88804f87a158 (&qdisc_xmit_lock_key#3){+.-.}-{3:3}, at: __netif_tx_lock include/linux/netdevice.h:4847 [inline] ffff88804f87a158 (&qdisc_xmit_lock_key#3){+.-.}-{3:3}, at: sch_direct_xmit+0x15f/0x4c0 net/sched/sch_generic.c:370 but task is already holding lock: ffff88807fae0158 (&qdisc_xmit_lock_key#3){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:347 [inline] ffff88807fae0158 (&qdisc_xmit_lock_key#3){+.-.}-{3:3}, at: __netif_tx_lock include/linux/netdevice.h:4847 [inline] ffff88807fae0158 (&qdisc_xmit_lock_key#3){+.-.}-{3:3}, at: sch_direct_xmit+0x15f/0x4c0 net/sched/sch_generic.c:370 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&qdisc_xmit_lock_key#3); lock(&qdisc_xmit_lock_key#3); *** DEADLOCK *** May be due to missing lock nesting notation locks held by kworker/0:5/5732: 15, last CPU#0: #0: ffff888032d81140 ((wq_completion)mld){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff888032d81140 ((wq_completion)mld){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff888032d81140 ((wq_completion)mld){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline] #0: ffff888032d81140 ((wq_completion)mld){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479 #1: ffffc90004aefc40 ((work_completion)(&(&idev->mc_ifc_work)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc90004aefc40 ((work_completion)(&(&idev->mc_ifc_work)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc90004aefc40 ((work_completion)(&(&idev->mc_ifc_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline] #1: ffffc90004aefc40 ((work_completion)(&(&idev->mc_ifc_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479 #2: ffff88807faf9530 (&idev->mc_lock){+.+.}-{4:4}, at: mld_ifc_work+0x2d/0xd60 net/ipv6/mcast.c:2738 #3: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #3: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #3: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: mld_sendpack+0x206/0xe10 net/ipv6/mcast.c:1862 #4: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #4: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #4: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: ip6_output+0x11e/0x540 net/ipv6/ip6_output.c:236 #5: ffffffff8ed5c940 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #5: ffffffff8ed5c940 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:902 [inline] #5: ffffffff8ed5c940 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x29b/0x3820 net/core/dev.c:4844 #6: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #6: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #6: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: bond_start_xmit+0xb4/0x19e0 drivers/net/bonding/bond_main.c:5599 #7: ffffffff8ed5c940 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #7: ffffffff8ed5c940 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:902 [inline] #7: ffffffff8ed5c940 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x29b/0x3820 net/core/dev.c:4844 #8: ffff88801238f228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#4){+...}-{3:3}, at: spin_trylock include/linux/spinlock.h:359 [inline] #8: ffff88801238f228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#4){+...}-{3:3}, at: qdisc_run_begin include/net/sch_generic.h:206 [inline] #8: ffff88801238f228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#4){+...}-{3:3}, at: __dev_xmit_skb net/core/dev.c:4249 [inline] #8: ffff88801238f228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#4){+...}-{3:3}, at: __dev_queue_xmit+0x1143/0x3820 net/core/dev.c:4884 #9: ffff88807fae0158 (&qdisc_xmit_lock_key#3){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:347 [inline] #9: ffff88807fae0158 (&qdisc_xmit_lock_key#3){+.-.}-{3:3}, at: __netif_tx_lock include/linux/netdevice.h:4847 [inline] #9: ffff88807fae0158 (&qdisc_xmit_lock_key#3){+.-.}-{3:3}, at: sch_direct_xmit+0x15f/0x4c0 net/sched/sch_generic.c:370 #10: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #10: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #10: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: ip_output+0x5a/0x450 net/ipv4/ip_output.c:432 #11: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #11: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #11: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: ip_finish_output2+0x3de/0x10b0 net/ipv4/ip_output.c:229 #12: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #12: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #12: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: arp_xmit+0x23/0x270 net/ipv4/arp.c:666 #13: ffffffff8ed5c940 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #13: ffffffff8ed5c940 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:902 [inline] #13: ffffffff8ed5c940 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x29b/0x3820 net/core/dev.c:4844 #14: ffff88807caa5228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#4){+...}-{3:3}, at: spin_trylock include/linux/spinlock.h:359 [inline] #14: ffff88807caa5228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#4){+...}-{3:3}, at: qdisc_run_begin include/net/sch_generic.h:206 [inline] #14: ffff88807caa5228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#4){+...}-{3:3}, at: __dev_xmit_skb net/core/dev.c:4249 [inline] #14: ffff88807caa5228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#4){+...}-{3:3}, at: __dev_queue_xmit+0x1143/0x3820 net/core/dev.c:4884 stack backtrace: CPU: 0 UID: 0 PID: 5732 Comm: kworker/0:5 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Workqueue: mld mld_ifc_work Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_deadlock_bug+0x27a/0x290 kernel/locking/lockdep.c:3085 check_deadlock kernel/locking/lockdep.c:3137 [inline] validate_chain kernel/locking/lockdep.c:3939 [inline] __lock_acquire+0x25db/0x2de0 kernel/locking/lockdep.c:5288 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942 __raw_spin_lock include/linux/spinlock_api_smp.h:190 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:173 spin_lock include/linux/spinlock.h:347 [inline] __netif_tx_lock include/linux/netdevice.h:4847 [inline] sch_direct_xmit+0x15f/0x4c0 net/sched/sch_generic.c:370 __dev_xmit_skb net/core/dev.c:4262 [inline] __dev_queue_xmit+0x177f/0x3820 net/core/dev.c:4884 NF_HOOK+0x33a/0x3c0 include/linux/netfilter.h:-1 arp_xmit+0x16c/0x270 net/ipv4/arp.c:668 arp_solicit+0xbdc/0xe40 net/ipv4/arp.c:395 neigh_probe net/core/neighbour.c:1087 [inline] __neigh_event_send+0xf0c/0x1510 net/core/neighbour.c:1267 neigh_event_send_probe include/net/neighbour.h:474 [inline] neigh_event_send include/net/neighbour.h:480 [inline] neigh_resolve_output+0x1a1/0x720 net/core/neighbour.c:1604 neigh_output include/net/neighbour.h:554 [inline] ip_finish_output2+0xc4b/0x10b0 net/ipv4/ip_output.c:236 NF_HOOK_COND include/linux/netfilter.h:314 [inline] ip_output+0x29f/0x450 net/ipv4/ip_output.c:437 iptunnel_xmit+0x626/0xd10 net/ipv4/ip_tunnel_core.c:97 ip_tunnel_xmit+0x195b/0x2040 net/ipv4/ip_tunnel.c:852 erspan_xmit+0xb6a/0x1620 net/ipv4/ip_gre.c:752 __netdev_start_xmit include/linux/netdevice.h:5438 [inline] netdev_start_xmit include/linux/netdevice.h:5447 [inline] xmit_one net/core/dev.c:3937 [inline] dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3953 sch_direct_xmit+0x257/0x4c0 net/sched/sch_generic.c:372 __dev_xmit_skb net/core/dev.c:4262 [inline] __dev_queue_xmit+0x177f/0x3820 net/core/dev.c:4884 __bond_start_xmit drivers/net/bonding/bond_main.c:5579 [inline] bond_start_xmit+0x70a/0x19e0 drivers/net/bonding/bond_main.c:5601 __netdev_start_xmit include/linux/netdevice.h:5438 [inline] netdev_start_xmit include/linux/netdevice.h:5447 [inline] xmit_one net/core/dev.c:3937 [inline] dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3953 __dev_queue_xmit+0x14c0/0x3820 net/core/dev.c:4926 NF_HOOK_COND include/linux/netfilter.h:314 [inline] ip6_output+0x337/0x540 net/ipv6/ip6_output.c:248 dst_output include/net/dst.h:471 [inline] NF_HOOK+0x177/0x4f0 include/linux/netfilter.h:325 mld_sendpack+0x890/0xe10 net/ipv6/mcast.c:1890 mld_send_cr net/ipv6/mcast.c:2191 [inline] mld_ifc_work+0x842/0xd60 net/ipv6/mcast.c:2739 process_one_work kernel/workqueue.c:3396 [inline] process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 ip6_tunnel: ip6tnl2 xmit: Local address not yet configured! ip6_tunnel: ip6tnl2 xmit: Local address not yet configured! net_ratelimit: 18 callbacks suppressed GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog net_ratelimit: 5 callbacks suppressed GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog