============================================ WARNING: possible recursive locking detected 4.15.0-rc7+ #170 Not tainted -------------------------------------------- syzkaller979616/3645 is trying to acquire lock: (_xmit_ETHER#2){+.-.}, at: [<00000000987e864d>] spin_lock include/linux/spinlock.h:310 [inline] (_xmit_ETHER#2){+.-.}, at: [<00000000987e864d>] __netif_tx_lock include/linux/netdevice.h:3537 [inline] (_xmit_ETHER#2){+.-.}, at: [<00000000987e864d>] sch_direct_xmit+0x280/0x6d0 net/sched/sch_generic.c:185 but task is already holding lock: (_xmit_ETHER#2){+.-.}, at: [<00000000987e864d>] spin_lock include/linux/spinlock.h:310 [inline] (_xmit_ETHER#2){+.-.}, at: [<00000000987e864d>] __netif_tx_lock include/linux/netdevice.h:3537 [inline] (_xmit_ETHER#2){+.-.}, at: [<00000000987e864d>] sch_direct_xmit+0x280/0x6d0 net/sched/sch_generic.c:185 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 10 locks held by syzkaller979616/3645: #0: (&tfile->napi_mutex){+.+.}, at: [<00000000b3f837b9>] tun_get_user+0xe5a/0x3710 drivers/net/tun.c:1636 #1: (rcu_read_lock){....}, at: [<00000000e0413f0a>] arch_static_branch arch/x86/include/asm/jump_label.h:36 [inline] #1: (rcu_read_lock){....}, at: [<00000000e0413f0a>] static_key_false include/linux/jump_label.h:142 [inline] #1: (rcu_read_lock){....}, at: [<00000000e0413f0a>] netif_receive_skb_internal+0xa2/0x670 net/core/dev.c:4585 #2: (k-slock-AF_INET){+...}, at: [<00000000ade6e71d>] spin_trylock include/linux/spinlock.h:320 [inline] #2: (k-slock-AF_INET){+...}, at: [<00000000ade6e71d>] icmp_xmit_lock net/ipv4/icmp.c:219 [inline] #2: (k-slock-AF_INET){+...}, at: [<00000000ade6e71d>] icmp_send+0x75e/0x19d0 net/ipv4/icmp.c:668 #3: (rcu_read_lock_bh){....}, at: [<000000004d9ab92d>] lwtunnel_xmit_redirect include/net/lwtunnel.h:92 [inline] #3: (rcu_read_lock_bh){....}, at: [<000000004d9ab92d>] ip_finish_output2+0x2b6/0x1500 net/ipv4/ip_output.c:213 #4: (rcu_read_lock_bh){....}, at: [<00000000ab86e730>] __dev_queue_xmit+0x294/0x2920 net/core/dev.c:3434 #5: (dev->qdisc_running_key ?: &qdisc_running_key){+...}, at: [<000000006aa64552>] dev_queue_xmit+0x17/0x20 net/core/dev.c:3533 #6: (_xmit_ETHER#2){+.-.}, at: [<00000000987e864d>] spin_lock include/linux/spinlock.h:310 [inline] #6: (_xmit_ETHER#2){+.-.}, at: [<00000000987e864d>] __netif_tx_lock include/linux/netdevice.h:3537 [inline] #6: (_xmit_ETHER#2){+.-.}, at: [<00000000987e864d>] sch_direct_xmit+0x280/0x6d0 net/sched/sch_generic.c:185 #7: (rcu_read_lock_bh){....}, at: [<000000004d9ab92d>] lwtunnel_xmit_redirect include/net/lwtunnel.h:92 [inline] #7: (rcu_read_lock_bh){....}, at: [<000000004d9ab92d>] ip_finish_output2+0x2b6/0x1500 net/ipv4/ip_output.c:213 #8: (rcu_read_lock_bh){....}, at: [<00000000ab86e730>] __dev_queue_xmit+0x294/0x2920 net/core/dev.c:3434 #9: (dev->qdisc_running_key ?: &qdisc_running_key){+...}, at: [<000000006aa64552>] dev_queue_xmit+0x17/0x20 net/core/dev.c:3533 stack backtrace: CPU: 1 PID: 3645 Comm: syzkaller979616 Not tainted 4.15.0-rc7+ #170 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 print_deadlock_bug kernel/locking/lockdep.c:1756 [inline] check_deadlock kernel/locking/lockdep.c:1800 [inline] validate_chain kernel/locking/lockdep.c:2396 [inline] __lock_acquire+0xe8f/0x3e00 kernel/locking/lockdep.c:3426 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3914 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:144 spin_lock include/linux/spinlock.h:310 [inline] __netif_tx_lock include/linux/netdevice.h:3537 [inline] sch_direct_xmit+0x280/0x6d0 net/sched/sch_generic.c:185 __dev_xmit_skb net/core/dev.c:3201 [inline] __dev_queue_xmit+0x1ce2/0x2920 net/core/dev.c:3468 dev_queue_xmit+0x17/0x20 net/core/dev.c:3533 neigh_resolve_output+0x5e2/0xa00 net/core/neighbour.c:1350 neigh_output include/net/neighbour.h:482 [inline] ip_finish_output2+0x8d2/0x1500 net/ipv4/ip_output.c:229 ip_finish_output+0x864/0xd10 net/ipv4/ip_output.c:317 NF_HOOK_COND include/linux/netfilter.h:239 [inline] ip_mc_output+0x277/0x1360 net/ipv4/ip_output.c:390 dst_output include/net/dst.h:460 [inline] ip_local_out+0x95/0x160 net/ipv4/ip_output.c:124 iptunnel_xmit+0x556/0x810 net/ipv4/ip_tunnel_core.c:91 ip_tunnel_xmit+0x1780/0x3650 net/ipv4/ip_tunnel.c:786 __gre_xmit+0x546/0x8b0 net/ipv4/ip_gre.c:436 erspan_xmit+0x409/0x13b0 net/ipv4/ip_gre.c:742 __netdev_start_xmit include/linux/netdevice.h:4042 [inline] netdev_start_xmit include/linux/netdevice.h:4051 [inline] xmit_one net/core/dev.c:3003 [inline] dev_hard_start_xmit+0x24e/0xac0 net/core/dev.c:3019 sch_direct_xmit+0x31d/0x6d0 net/sched/sch_generic.c:187 __dev_xmit_skb net/core/dev.c:3201 [inline] __dev_queue_xmit+0x1ce2/0x2920 net/core/dev.c:3468 dev_queue_xmit+0x17/0x20 net/core/dev.c:3533 neigh_resolve_output+0x5e2/0xa00 net/core/neighbour.c:1350 neigh_output include/net/neighbour.h:482 [inline] ip_finish_output2+0x8d2/0x1500 net/ipv4/ip_output.c:229 ip_finish_output+0x864/0xd10 net/ipv4/ip_output.c:317 NF_HOOK_COND include/linux/netfilter.h:239 [inline] ip_mc_output+0x277/0x1360 net/ipv4/ip_output.c:390 dst_output include/net/dst.h:460 [inline] ip_local_out+0x95/0x160 net/ipv4/ip_output.c:124 ip_send_skb+0x3c/0xc0 net/ipv4/ip_output.c:1414 ip_push_pending_frames+0x64/0x80 net/ipv4/ip_output.c:1434 icmp_push_reply+0x395/0x4f0 net/ipv4/icmp.c:394 icmp_send+0x1148/0x19d0 net/ipv4/icmp.c:741 ip_options_compile+0xc21/0x1a50 net/ipv4/ip_options.c:472 ip_rcv_options net/ipv4/ip_input.c:284 [inline] ip_rcv_finish+0x80f/0x1e30 net/ipv4/ip_input.c:365 NF_HOOK include/linux/netfilter.h:250 [inline] ip_rcv+0xc5a/0x1840 net/ipv4/ip_input.c:493 __netif_receive_skb_core+0x1a41/0x3460 net/core/dev.c:4473 __netif_receive_skb+0x2c/0x1b0 net/core/dev.c:4538 netif_receive_skb_internal+0x10b/0x670 net/core/dev.c:4611 napi_frags_finish net/core/dev.c:5052 [inline] napi_gro_frags+0x58a/0xaf0 net/core/dev.c:5125 tun_get_user+0x262e/0x3710 drivers/net/tun.c:1757 tun_chr_write_iter+0xb9/0x160 drivers/net/tun.c:1800 call_write_iter include/linux/fs.h:1772 [inline] do_iter_readv_writev+0x525/0x7f0 fs/read_write.c:653 do_iter_write+0x154/0x540 fs/read_write.c:932 compat_writev+0x225/0x420 fs/read_write.c:1246 do_compat_writev+0x115/0x220 fs/read_write.c:1267 C_SYSC_writev fs/read_write.c:1278 [inline] compat_SyS_writev+0x26/0x30 fs/read_write.c:1274 do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline] do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389 entry_SYSENTER_compat+0x54/0x63 arch/x86/entry/entry_64_compat.S:129 RIP: 0023:0xf7f87c79 RSP: 002b:00000000ffb2aa08 EFLAGS: 00000246 ORIG_RAX: 0000000000000092