============================================ WARNING: possible recursive locking detected 5.14.0-rc7-syzkaller #0 Not tainted -------------------------------------------- syz-executor.0/3182 is trying to acquire lock: ffff888038277398 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline] ffff888038277398 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4379 [inline] ffff888038277398 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x1a1/0x5b0 net/sched/sch_generic.c:340 but task is already holding lock: ffff8880169ebc98 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline] ffff8880169ebc98 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4379 [inline] ffff8880169ebc98 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x1a1/0x5b0 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 7 locks held by syz-executor.0/3182: #0: ffffffff8c717f20 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:267 #1: ffffffff8c717f20 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:267 #2: ffff888012bc6258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:364 [inline] #2: ffff888012bc6258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:173 [inline] #2: ffff888012bc6258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3873 [inline] #2: ffff888012bc6258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x1340/0x34b0 net/core/dev.c:4253 #3: ffff8880169ebc98 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline] #3: ffff8880169ebc98 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4379 [inline] #3: ffff8880169ebc98 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x1a1/0x5b0 net/sched/sch_generic.c:340 #4: ffffffff8c717f20 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:267 #5: ffffffff8c717f20 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:267 #6: ffff888019744258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:364 [inline] #6: ffff888019744258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:173 [inline] #6: ffff888019744258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3873 [inline] #6: ffff888019744258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x1340/0x34b0 net/core/dev.c:4253 stack backtrace: CPU: 0 PID: 3182 Comm: syz-executor.0 Not tainted 5.14.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1ae/0x29f lib/dump_stack.c:105 __lock_acquire+0x2615/0x6100 kernel/locking/lockdep.c:4853 lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:354 [inline] __netif_tx_lock include/linux/netdevice.h:4379 [inline] sch_direct_xmit+0x1a1/0x5b0 net/sched/sch_generic.c:340 __dev_xmit_skb net/core/dev.c:3886 [inline] __dev_queue_xmit+0x1a2e/0x34b0 net/core/dev.c:4253 neigh_output include/net/neighbour.h:510 [inline] ip_finish_output2+0x79a/0x19f0 net/ipv4/ip_output.c:230 iptunnel_xmit+0x46b/0x810 net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x1bbd/0x25f0 net/ipv4/ip_tunnel.c:810 __gre_xmit net/ipv4/ip_gre.c:471 [inline] erspan_xmit+0x11f3/0x29a0 net/ipv4/ip_gre.c:709 __netdev_start_xmit include/linux/netdevice.h:4944 [inline] netdev_start_xmit include/linux/netdevice.h:4958 [inline] xmit_one net/core/dev.c:3659 [inline] dev_hard_start_xmit+0x20b/0x450 net/core/dev.c:3675 sch_direct_xmit+0x292/0x5b0 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3886 [inline] __dev_queue_xmit+0x1a2e/0x34b0 net/core/dev.c:4253 neigh_output include/net/neighbour.h:510 [inline] ip_finish_output2+0x79a/0x19f0 net/ipv4/ip_output.c:230 dst_output include/net/dst.h:448 [inline] ip_local_out net/ipv4/ip_output.c:126 [inline] ip_send_skb+0x113/0x1a0 net/ipv4/ip_output.c:1572 udp_send_skb+0x97e/0x1240 net/ipv4/udp.c:966 udp_sendmsg+0x21ee/0x3260 net/ipv4/udp.c:1253 udpv6_sendmsg+0xa5c/0x3590 net/ipv6/udp.c:1359 sock_sendmsg_nosec net/socket.c:703 [inline] sock_sendmsg net/socket.c:723 [inline] ____sys_sendmsg+0x5a2/0x900 net/socket.c:2392 ___sys_sendmsg net/socket.c:2446 [inline] __sys_sendmmsg+0x500/0x790 net/socket.c:2532 __do_sys_sendmmsg net/socket.c:2561 [inline] __se_sys_sendmmsg net/socket.c:2558 [inline] __x64_sys_sendmmsg+0x9c/0xb0 net/socket.c:2558 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4665f9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fdf4bfc3188 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665f9 RDX: 0400000000000132 RSI: 0000000020004d80 RDI: 0000000000000003 RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000004000000 R11: 0000000000000246 R12: 000000000056bf80 R13: 00007ffedb45ba2f R14: 00007fdf4bfc3300 R15: 0000000000022000