====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ swapper/0/0 is trying to acquire lock: ffff88802c7aa218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff88802c7aa218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+.-.}-{3:3}, at: __dev_xmit_skb net/core/dev.c:4186 [inline] ffff88802c7aa218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+.-.}-{3:3}, at: __dev_queue_xmit+0x33ff/0x4490 net/core/dev.c:4729 but task is already holding lock: ffff888032a79958 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff888032a79958 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}, at: __netif_tx_lock include/linux/netdevice.h:4685 [inline] ffff888032a79958 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}, at: sch_direct_xmit+0x3ba/0xcf0 net/sched/sch_generic.c:342 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}: __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] __netif_tx_lock include/linux/netdevice.h:4685 [inline] sch_direct_xmit+0x3ba/0xcf0 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:4152 [inline] __dev_queue_xmit+0x144d/0x4490 net/core/dev.c:4729 dev_queue_xmit include/linux/netdevice.h:3365 [inline] neigh_resolve_output net/core/neighbour.c:1595 [inline] neigh_resolve_output+0x53a/0x940 net/core/neighbour.c:1575 neigh_output include/net/neighbour.h:547 [inline] ip6_finish_output2+0xad1/0x1cf0 net/ipv6/ip6_output.c:136 __ip6_finish_output+0x3cd/0x1010 net/ipv6/ip6_output.c:209 ip6_finish_output net/ipv6/ip6_output.c:220 [inline] NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip6_output+0x253/0x710 net/ipv6/ip6_output.c:247 dst_output include/net/dst.h:464 [inline] NF_HOOK include/linux/netfilter.h:318 [inline] NF_HOOK include/linux/netfilter.h:312 [inline] mld_sendpack+0xac1/0x1350 net/ipv6/mcast.c:1855 mld_send_cr net/ipv6/mcast.c:2154 [inline] mld_ifc_work+0x740/0xbf0 net/ipv6/mcast.c:2693 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3263 process_scheduled_works kernel/workqueue.c:3346 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #0 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+.-.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x126f/0x1c90 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] __dev_xmit_skb net/core/dev.c:4186 [inline] __dev_queue_xmit+0x33ff/0x4490 net/core/dev.c:4729 dev_queue_xmit include/linux/netdevice.h:3365 [inline] neigh_resolve_output net/core/neighbour.c:1595 [inline] neigh_resolve_output+0x53a/0x940 net/core/neighbour.c:1575 neigh_output include/net/neighbour.h:547 [inline] ip6_finish_output2+0xad1/0x1cf0 net/ipv6/ip6_output.c:136 __ip6_finish_output+0x3cd/0x1010 net/ipv6/ip6_output.c:209 ip6_finish_output net/ipv6/ip6_output.c:220 [inline] NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip6_output+0x253/0x710 net/ipv6/ip6_output.c:247 dst_output include/net/dst.h:464 [inline] NF_HOOK include/linux/netfilter.h:318 [inline] ndisc_send_skb+0xa85/0x1f50 net/ipv6/ndisc.c:512 ndisc_send_ns+0xc6/0x140 net/ipv6/ndisc.c:670 ndisc_solicit+0x2f6/0x510 net/ipv6/ndisc.c:761 neigh_probe+0xce/0x110 net/core/neighbour.c:1098 __neigh_event_send+0xac5/0x13c0 net/core/neighbour.c:1271 neigh_event_send_probe include/net/neighbour.h:471 [inline] neigh_event_send include/net/neighbour.h:477 [inline] neigh_event_send include/net/neighbour.h:475 [inline] neigh_resolve_output+0x56b/0x940 net/core/neighbour.c:1579 neigh_output include/net/neighbour.h:547 [inline] ip6_finish_output2+0xad1/0x1cf0 net/ipv6/ip6_output.c:136 __ip6_finish_output+0x3cd/0x1010 net/ipv6/ip6_output.c:209 ip6_finish_output net/ipv6/ip6_output.c:220 [inline] NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip6_output+0x253/0x710 net/ipv6/ip6_output.c:247 dst_output include/net/dst.h:464 [inline] ip6_local_out+0xd1/0x4d0 net/ipv6/output_core.c:157 ip6_send_skb+0x112/0x460 net/ipv6/ip6_output.c:1994 ip6_push_pending_frames+0xdd/0x100 net/ipv6/ip6_output.c:2015 icmpv6_push_pending_frames+0x2dc/0x460 net/ipv6/icmp.c:312 icmp6_send+0x1ec9/0x2be0 net/ipv6/icmp.c:633 __icmpv6_send include/linux/icmpv6.h:28 [inline] icmpv6_send include/linux/icmpv6.h:49 [inline] ip6_link_failure+0x31/0x5a0 net/ipv6/route.c:2843 dst_link_failure include/net/dst.h:432 [inline] ip_tunnel_xmit+0x2fd7/0x3850 net/ipv4/ip_tunnel.c:851 __gre_xmit+0x8bb/0xc00 net/ipv4/ip_gre.c:488 erspan_xmit+0x56b/0x25d0 net/ipv4/ip_gre.c:747 __netdev_start_xmit include/linux/netdevice.h:5248 [inline] netdev_start_xmit include/linux/netdevice.h:5257 [inline] xmit_one net/core/dev.c:3845 [inline] dev_hard_start_xmit+0x97/0x740 net/core/dev.c:3861 sch_direct_xmit+0x1b2/0xcf0 net/sched/sch_generic.c:344 qdisc_restart net/sched/sch_generic.c:409 [inline] __qdisc_run+0x54a/0x1c00 net/sched/sch_generic.c:417 qdisc_run include/net/pkt_sched.h:126 [inline] qdisc_run include/net/pkt_sched.h:123 [inline] net_tx_action+0x74f/0xce0 net/core/dev.c:5724 handle_softirqs+0x219/0x8e0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0x109/0x170 kernel/softirq.c:723 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline] sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1052 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline] pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:81 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:767 default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:190 [inline] do_idle+0x38d/0x500 kernel/sched/idle.c:330 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:428 rest_init+0x16b/0x2b0 init/main.c:757 start_kernel+0x3f6/0x4e0 init/main.c:1111 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x148 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&qdisc_xmit_lock_key#4); lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3); lock(&qdisc_xmit_lock_key#4); lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3); *** DEADLOCK *** 9 locks held by swapper/0/0: #0: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #0: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: net_tx_action+0x39a/0xce0 net/core/dev.c:5693 #1: ffff888032a79958 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline] #1: ffff888032a79958 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}, at: __netif_tx_lock include/linux/netdevice.h:4685 [inline] #1: ffff888032a79958 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}, at: sch_direct_xmit+0x3ba/0xcf0 net/sched/sch_generic.c:342 #2: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #2: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #2: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: icmp6_send+0x24c/0x2be0 net/ipv6/icmp.c:478 #3: ffff8881053481e0 (k-slock-AF_INET6){+.-.}-{3:3}, at: spin_trylock include/linux/spinlock.h:361 [inline] #3: ffff8881053481e0 (k-slock-AF_INET6){+.-.}-{3:3}, at: icmpv6_xmit_lock net/ipv6/icmp.c:108 [inline] #3: ffff8881053481e0 (k-slock-AF_INET6){+.-.}-{3:3}, at: icmp6_send+0x8a5/0x2be0 net/ipv6/icmp.c:555 #4: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #4: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #4: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: ip6_send_skb+0xb9/0x460 net/ipv6/ip6_output.c:1993 #5: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #5: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #5: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: ip6_output+0xe3/0x710 net/ipv6/ip6_output.c:235 #6: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #6: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #6: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: ndisc_send_skb+0x1ab/0x1f50 net/ipv6/ndisc.c:482 #7: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #7: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #7: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: ip6_output+0xe3/0x710 net/ipv6/ip6_output.c:235 #8: ffffffff8e3c46c0 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #8: ffffffff8e3c46c0 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:918 [inline] #8: ffffffff8e3c46c0 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x276/0x4490 net/core/dev.c:4688 stack backtrace: CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_circular_bug+0x275/0x350 kernel/locking/lockdep.c:2043 check_noncircular+0x14c/0x170 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x126f/0x1c90 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] __dev_xmit_skb net/core/dev.c:4186 [inline] __dev_queue_xmit+0x33ff/0x4490 net/core/dev.c:4729 dev_queue_xmit include/linux/netdevice.h:3365 [inline] neigh_resolve_output net/core/neighbour.c:1595 [inline] neigh_resolve_output+0x53a/0x940 net/core/neighbour.c:1575 neigh_output include/net/neighbour.h:547 [inline] ip6_finish_output2+0xad1/0x1cf0 net/ipv6/ip6_output.c:136 __ip6_finish_output+0x3cd/0x1010 net/ipv6/ip6_output.c:209 ip6_finish_output net/ipv6/ip6_output.c:220 [inline] NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip6_output+0x253/0x710 net/ipv6/ip6_output.c:247 dst_output include/net/dst.h:464 [inline] NF_HOOK include/linux/netfilter.h:318 [inline] ndisc_send_skb+0xa85/0x1f50 net/ipv6/ndisc.c:512 ndisc_send_ns+0xc6/0x140 net/ipv6/ndisc.c:670 ndisc_solicit+0x2f6/0x510 net/ipv6/ndisc.c:761 neigh_probe+0xce/0x110 net/core/neighbour.c:1098 __neigh_event_send+0xac5/0x13c0 net/core/neighbour.c:1271 neigh_event_send_probe include/net/neighbour.h:471 [inline] neigh_event_send include/net/neighbour.h:477 [inline] neigh_event_send include/net/neighbour.h:475 [inline] neigh_resolve_output+0x56b/0x940 net/core/neighbour.c:1579 neigh_output include/net/neighbour.h:547 [inline] ip6_finish_output2+0xad1/0x1cf0 net/ipv6/ip6_output.c:136 __ip6_finish_output+0x3cd/0x1010 net/ipv6/ip6_output.c:209 ip6_finish_output net/ipv6/ip6_output.c:220 [inline] NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip6_output+0x253/0x710 net/ipv6/ip6_output.c:247 dst_output include/net/dst.h:464 [inline] ip6_local_out+0xd1/0x4d0 net/ipv6/output_core.c:157 ip6_send_skb+0x112/0x460 net/ipv6/ip6_output.c:1994 ip6_push_pending_frames+0xdd/0x100 net/ipv6/ip6_output.c:2015 icmpv6_push_pending_frames+0x2dc/0x460 net/ipv6/icmp.c:312 icmp6_send+0x1ec9/0x2be0 net/ipv6/icmp.c:633 __icmpv6_send include/linux/icmpv6.h:28 [inline] icmpv6_send include/linux/icmpv6.h:49 [inline] ip6_link_failure+0x31/0x5a0 net/ipv6/route.c:2843 dst_link_failure include/net/dst.h:432 [inline] ip_tunnel_xmit+0x2fd7/0x3850 net/ipv4/ip_tunnel.c:851 __gre_xmit+0x8bb/0xc00 net/ipv4/ip_gre.c:488 erspan_xmit+0x56b/0x25d0 net/ipv4/ip_gre.c:747 __netdev_start_xmit include/linux/netdevice.h:5248 [inline] netdev_start_xmit include/linux/netdevice.h:5257 [inline] xmit_one net/core/dev.c:3845 [inline] dev_hard_start_xmit+0x97/0x740 net/core/dev.c:3861 sch_direct_xmit+0x1b2/0xcf0 net/sched/sch_generic.c:344 qdisc_restart net/sched/sch_generic.c:409 [inline] __qdisc_run+0x54a/0x1c00 net/sched/sch_generic.c:417 qdisc_run include/net/pkt_sched.h:126 [inline] qdisc_run include/net/pkt_sched.h:123 [inline] net_tx_action+0x74f/0xce0 net/core/dev.c:5724 handle_softirqs+0x219/0x8e0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0x109/0x170 kernel/softirq.c:723 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline] sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1052 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82 Code: d7 6c 02 c3 cc cc cc cc 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa eb 07 0f 00 2d e3 84 29 00 fb f4 3c 0a 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 RSP: 0018:ffffffff8e007df8 EFLAGS: 00000286 RAX: 00000000003afbbd RBX: 0000000000000000 RCX: ffffffff8b60a2a9 RDX: 0000000000000000 RSI: ffffffff8da2b882 RDI: ffffffff8bf07040 RBP: fffffbfff1c12f40 R08: 0000000000000001 R09: ffffed100d486655 R10: ffff88806a4332ab R11: 0000000000000001 R12: 0000000000000000 R13: ffffffff8e097a00 R14: ffffffff90820dd0 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:767 default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:190 [inline] do_idle+0x38d/0x500 kernel/sched/idle.c:330 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:428 rest_init+0x16b/0x2b0 init/main.c:757 start_kernel+0x3f6/0x4e0 init/main.c:1111 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x148 ---------------- Code disassembly (best guess): 0: d7 xlat %ds:(%rbx) 1: 6c insb (%dx),%es:(%rdi) 2: 02 c3 add %bl,%al 4: cc int3 5: cc int3 6: cc int3 7: cc int3 8: 0f 1f 00 nopl (%rax) b: 90 nop c: 90 nop d: 90 nop e: 90 nop f: 90 nop 10: 90 nop 11: 90 nop 12: 90 nop 13: 90 nop 14: 90 nop 15: 90 nop 16: 90 nop 17: 90 nop 18: 90 nop 19: 90 nop 1a: 90 nop 1b: f3 0f 1e fa endbr64 1f: eb 07 jmp 0x28 21: 0f 00 2d e3 84 29 00 verw 0x2984e3(%rip) # 0x29850b 28: fb sti 29: f4 hlt * 2a: e9 3c 0a 03 00 jmp 0x30a6b <-- trapping instruction 2f: 66 2e 0f 1f 84 00 00 cs nopw 0x0(%rax,%rax,1) 36: 00 00 00 39: 66 90 xchg %ax,%ax 3b: 90 nop 3c: 90 nop 3d: 90 nop 3e: 90 nop 3f: 90 nop