============================================ WARNING: possible recursive locking detected 5.16.0-rc2-syzkaller #0 Not tainted -------------------------------------------- kworker/1:21/10467 is trying to acquire lock: ffff8880155d8a18 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline] ffff8880155d8a18 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4055 [inline] ffff8880155d8a18 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x30f/0xbc0 net/sched/sch_generic.c:340 but task is already holding lock: ffff88808734e498 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline] ffff88808734e498 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4055 [inline] ffff88808734e498 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x30f/0xbc0 net/sched/sch_generic.c:340 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(_xmit_ETHER#2); lock(_xmit_ETHER#2); *** DEADLOCK *** May be due to missing lock nesting notation 11 locks held by kworker/1:21/10467: #0: ffff88814aa92538 ((wq_completion)mld){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff88814aa92538 ((wq_completion)mld){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline] #0: ffff88814aa92538 ((wq_completion)mld){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1198 [inline] #0: ffff88814aa92538 ((wq_completion)mld){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:635 [inline] #0: ffff88814aa92538 ((wq_completion)mld){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:662 [inline] #0: ffff88814aa92538 ((wq_completion)mld){+.+.}-{0:0}, at: process_one_work+0x896/0x1690 kernel/workqueue.c:2269 #1: ffffc900056a7db0 ((work_completion)(&(&idev->mc_ifc_work)->work)){+.+.}-{0:0}, at: process_one_work+0x8ca/0x1690 kernel/workqueue.c:2273 #2: ffff888029a6b530 (&idev->mc_lock){+.+.}-{3:3}, at: mld_ifc_work+0x3d/0xdc0 net/ipv6/mcast.c:2658 #3: ffffffff8bb83ca0 (rcu_read_lock){....}-{1:2}, at: read_pnet include/net/net_namespace.h:327 [inline] #3: ffffffff8bb83ca0 (rcu_read_lock){....}-{1:2}, at: dev_net include/linux/netdevice.h:2431 [inline] #3: ffffffff8bb83ca0 (rcu_read_lock){....}-{1:2}, at: mld_sendpack+0x15c/0xe40 net/ipv6/mcast.c:1793 #4: ffffffff8bb83c40 (rcu_read_lock_bh){....}-{1:2}, at: lwtunnel_xmit_redirect include/net/lwtunnel.h:95 [inline] #4: ffffffff8bb83c40 (rcu_read_lock_bh){....}-{1:2}, at: ip6_finish_output2+0x2ad/0x14f0 net/ipv6/ip6_output.c:112 #5: ffffffff8bb83c40 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x1e3/0x3620 net/core/dev.c:4036 #6: ffff888029a6f258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:359 [inline] #6: ffff888029a6f258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:187 [inline] #6: ffff888029a6f258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:184 [inline] #6: ffff888029a6f258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3687 [inline] #6: ffff888029a6f258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x1262/0x3620 net/core/dev.c:4077 #7: ffff88808734e498 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline] #7: ffff88808734e498 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4055 [inline] #7: ffff88808734e498 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x30f/0xbc0 net/sched/sch_generic.c:340 #8: ffffffff8bb83c40 (rcu_read_lock_bh){....}-{1:2}, at: lwtunnel_xmit_redirect include/net/lwtunnel.h:95 [inline] #8: ffffffff8bb83c40 (rcu_read_lock_bh){....}-{1:2}, at: ip_finish_output2+0x28c/0x2160 net/ipv4/ip_output.c:207 #9: ffffffff8bb83c40 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x1e3/0x3620 net/core/dev.c:4036 #10: ffff88807bdc9258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:359 [inline] #10: ffff88807bdc9258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:187 [inline] #10: ffff88807bdc9258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:184 [inline] #10: ffff88807bdc9258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3687 [inline] #10: ffff88807bdc9258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x1262/0x3620 net/core/dev.c:4077 stack backtrace: CPU: 1 PID: 10467 Comm: kworker/1:21 Not tainted 5.16.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: mld mld_ifc_work Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_deadlock_bug kernel/locking/lockdep.c:2956 [inline] check_deadlock kernel/locking/lockdep.c:2999 [inline] validate_chain kernel/locking/lockdep.c:3788 [inline] __lock_acquire.cold+0x149/0x3ab kernel/locking/lockdep.c:5027 lock_acquire kernel/locking/lockdep.c:5637 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5602 __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:349 [inline] __netif_tx_lock include/linux/netdevice.h:4055 [inline] sch_direct_xmit+0x30f/0xbc0 net/sched/sch_generic.c:340 __dev_xmit_skb net/core/dev.c:3700 [inline] __dev_queue_xmit+0x148f/0x3620 net/core/dev.c:4077 neigh_hh_output include/net/neighbour.h:522 [inline] neigh_output include/net/neighbour.h:536 [inline] ip_finish_output2+0x14d4/0x2160 net/ipv4/ip_output.c:221 __ip_finish_output net/ipv4/ip_output.c:299 [inline] __ip_finish_output+0x396/0x640 net/ipv4/ip_output.c:281 ip_finish_output+0x32/0x200 net/ipv4/ip_output.c:309 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip_output+0x196/0x310 net/ipv4/ip_output.c:423 dst_output include/net/dst.h:450 [inline] ip_local_out+0xaf/0x1a0 net/ipv4/ip_output.c:126 iptunnel_xmit+0x628/0xa50 net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x10a6/0x2b60 net/ipv4/ip_tunnel.c:810 gre_tap_xmit+0x4ff/0x630 net/ipv4/ip_gre.c:740 __netdev_start_xmit include/linux/netdevice.h:4608 [inline] netdev_start_xmit include/linux/netdevice.h:4622 [inline] xmit_one net/core/dev.c:3473 [inline] dev_hard_start_xmit+0x1eb/0x920 net/core/dev.c:3489 sch_direct_xmit+0x19f/0xbc0 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3700 [inline] __dev_queue_xmit+0x148f/0x3620 net/core/dev.c:4077 neigh_resolve_output net/core/neighbour.c:1523 [inline] neigh_resolve_output+0x50e/0x820 net/core/neighbour.c:1503 neigh_output include/net/neighbour.h:538 [inline] ip6_finish_output2+0x56e/0x14f0 net/ipv6/ip6_output.c:126 __ip6_finish_output net/ipv6/ip6_output.c:191 [inline] __ip6_finish_output+0x61e/0xe80 net/ipv6/ip6_output.c:170 ip6_finish_output+0x32/0x200 net/ipv6/ip6_output.c:201 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip6_output+0x1e4/0x530 net/ipv6/ip6_output.c:224 dst_output include/net/dst.h:450 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] mld_sendpack+0x9a1/0xe40 net/ipv6/mcast.c:1826 mld_send_cr net/ipv6/mcast.c:2127 [inline] mld_ifc_work+0x71c/0xdc0 net/ipv6/mcast.c:2659 process_one_work+0x9b2/0x1690 kernel/workqueue.c:2298 worker_thread+0x658/0x11f0 kernel/workqueue.c:2445 kthread+0x405/0x4f0 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295