============================================ WARNING: possible recursive locking detected 6.6.0-rc7-syzkaller-00195-g2af9b20dbb39 #0 Not tainted -------------------------------------------- syz-executor397/5170 is trying to acquire lock: ffff88802ecbd218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff88802ecbd218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3830 [inline] ffff88802ecbd218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x2e8f/0x3d60 net/core/dev.c:4335 but task is already holding lock: ffff88802cc1b258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] ffff88802cc1b258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:194 [inline] ffff88802cc1b258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:191 [inline] ffff88802cc1b258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3787 [inline] ffff88802cc1b258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x104a/0x3d60 net/core/dev.c:4335 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock); lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock); *** DEADLOCK *** May be due to missing lock nesting notation 6 locks held by syz-executor397/5170: #0: ffffffff8cba7a60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:303 [inline] #0: ffffffff8cba7a60 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:749 [inline] #0: ffffffff8cba7a60 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x367/0x2550 net/ipv4/ip_output.c:226 #1: ffffffff8cba7a00 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #1: ffffffff8cba7a00 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:801 [inline] #1: ffffffff8cba7a00 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x244/0x3d60 net/core/dev.c:4294 #2: ffff88802cc1b258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] #2: ffff88802cc1b258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:194 [inline] #2: ffff88802cc1b258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:191 [inline] #2: ffff88802cc1b258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3787 [inline] #2: ffff88802cc1b258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x104a/0x3d60 net/core/dev.c:4335 #3: ffff8880213024d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #3: ffff8880213024d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4352 [inline] #3: ffff8880213024d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x333/0xc20 net/sched/sch_generic.c:340 #4: ffffffff8cba7a60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:303 [inline] #4: ffffffff8cba7a60 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:749 [inline] #4: ffffffff8cba7a60 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x367/0x2550 net/ipv4/ip_output.c:226 #5: ffffffff8cba7a00 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #5: ffffffff8cba7a00 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:801 [inline] #5: ffffffff8cba7a00 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x244/0x3d60 net/core/dev.c:4294 stack backtrace: CPU: 1 PID: 5170 Comm: syz-executor397 Not tainted 6.6.0-rc7-syzkaller-00195-g2af9b20dbb39 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106 check_deadlock kernel/locking/lockdep.c:3062 [inline] validate_chain kernel/locking/lockdep.c:3855 [inline] __lock_acquire+0x2971/0x5de0 kernel/locking/lockdep.c:5136 lock_acquire kernel/locking/lockdep.c:5753 [inline] lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718 __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:3830 [inline] __dev_queue_xmit+0x2e8f/0x3d60 net/core/dev.c:4335 dev_queue_xmit include/linux/netdevice.h:3082 [inline] neigh_hh_output include/net/neighbour.h:526 [inline] neigh_output include/net/neighbour.h:540 [inline] ip_finish_output2+0x169f/0x2550 net/ipv4/ip_output.c:233 __ip_finish_output net/ipv4/ip_output.c:311 [inline] __ip_finish_output+0x38b/0x640 net/ipv4/ip_output.c:293 ip_finish_output+0x31/0x310 net/ipv4/ip_output.c:321 NF_HOOK_COND include/linux/netfilter.h:293 [inline] ip_output+0x13b/0x290 net/ipv4/ip_output.c:431 dst_output include/net/dst.h:458 [inline] ip_local_out+0xaf/0x190 net/ipv4/ip_output.c:127 iptunnel_xmit+0x61a/0x9e0 net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x1e4f/0x3370 net/ipv4/ip_tunnel.c:831 erspan_xmit+0x52b/0x1f90 net/ipv4/ip_gre.c:717 __netdev_start_xmit include/linux/netdevice.h:4889 [inline] netdev_start_xmit include/linux/netdevice.h:4903 [inline] xmit_one net/core/dev.c:3573 [inline] dev_hard_start_xmit+0x13d/0x6c0 net/core/dev.c:3589 sch_direct_xmit+0x1ac/0xc20 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3800 [inline] __dev_queue_xmit+0x126e/0x3d60 net/core/dev.c:4335 dev_queue_xmit include/linux/netdevice.h:3082 [inline] neigh_hh_output include/net/neighbour.h:526 [inline] neigh_output include/net/neighbour.h:540 [inline] ip_finish_output2+0x169f/0x2550 net/ipv4/ip_output.c:233 __ip_finish_output net/ipv4/ip_output.c:311 [inline] __ip_finish_output+0x38b/0x640 net/ipv4/ip_output.c:293 ip_finish_output+0x31/0x310 net/ipv4/ip_output.c:321 NF_HOOK_COND include/linux/netfilter.h:293 [inline] ip_output+0x13b/0x290 net/ipv4/ip_output.c:431 dst_output include/net/dst.h:458 [inline] ip_local_out net/ipv4/ip_output.c:127 [inline] ip_send_skb+0xd3/0x250 net/ipv4/ip_output.c:1486 udp_send_skb+0x73a/0x1490 net/ipv4/udp.c:963 udp_sendmsg+0x1a83/0x2b40 net/ipv4/udp.c:1246 inet_sendmsg+0x9d/0xe0 net/ipv4/af_inet.c:846 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0xd5/0x180 net/socket.c:745 ____sys_sendmsg+0x2ac/0x940 net/socket.c:2558 ___sys_sendmsg+0x135/0x1d0 net/socket.c:2612 __sys_sendmmsg+0x1a1/0x450 net/socket.c:2698 __do_sys_sendmmsg net/socket.c:2727 [inline] __se_sys_sendmmsg net/socket.c:2724 [inline] __x64_sys_sendmmsg+0x9c/0x100 net/socket.c:2724 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fd128058be9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 d1 19 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fff05002a88 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fd128058be9 RDX: 0400000000000075 RSI: 0000000020007fc0 RDI: 0000000000000003 RBP: 00000000000f4240 R08: 0000000100000000 R09: 0000000100000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff05002ae0 R13: 000000000000b34f R14: 00007fff05002aac R15: 0000000000000003