netdevsim netdevsim1 eth1: unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim1 eth2: unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim1 eth3: unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim1 eth0: unset [0, 0] type 1 family 0 port 8472 - 0 netdevsim netdevsim1 eth1: unset [0, 0] type 1 family 0 port 8472 - 0 netdevsim netdevsim1 eth2: unset [0, 0] type 1 family 0 port 8472 - 0 netdevsim netdevsim1 eth3: unset [0, 0] type 1 family 0 port 8472 - 0 ============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz.1.3709/20256 is trying to acquire lock: ffffffff8d44b148 (rtnl_mutex){+.+.}-{3:3}, at: ip_mc_drop_socket+0x7c/0x270 net/ipv4/igmp.c:2702 but task is already holding lock: ffffffff8d44b148 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline] ffffffff8d44b148 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7d6/0xf00 net/core/rtnetlink.c:5685 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(rtnl_mutex); lock(rtnl_mutex); *** DEADLOCK *** May be due to missing lock nesting notation 1 lock held by syz.1.3709/20256: #0: ffffffff8d44b148 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline] #0: ffffffff8d44b148 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7d6/0xf00 net/core/rtnetlink.c:5685 stack backtrace: CPU: 0 PID: 20256 Comm: syz.1.3709 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026 Call Trace: dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106 __lock_acquire+0x1247/0x7b50 kernel/locking/lockdep.c:-1 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623 __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743 ip_mc_drop_socket+0x7c/0x270 net/ipv4/igmp.c:2702 inet_release+0x47/0x180 net/ipv4/af_inet.c:419 __sock_release net/socket.c:651 [inline] sock_release+0x7b/0x140 net/socket.c:679 vxlan_sock_release+0x385/0x400 drivers/net/vxlan/vxlan_core.c:1637 vxlan_stop+0xf62/0x1090 drivers/net/vxlan/vxlan_core.c:3156 __dev_close_many+0x1d3/0x2b0 net/core/dev.c:1634 __dev_close net/core/dev.c:1646 [inline] __dev_change_flags+0x2c9/0x6a0 net/core/dev.c:8877 dev_change_flags+0x78/0x1a0 net/core/dev.c:8950 do_setlink+0xca4/0x29d0 net/core/rtnetlink.c:2785 rtnl_group_changelink net/core/rtnetlink.c:3302 [inline] __rtnl_newlink net/core/rtnetlink.c:3466 [inline] rtnl_newlink+0xfee/0x1920 net/core/rtnetlink.c:3578 rtnetlink_rcv_msg+0x82c/0xf00 net/core/rtnetlink.c:5688 netlink_rcv_skb+0x1e9/0x430 net/netlink/af_netlink.c:2512 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x78f/0x940 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1923 sock_sendmsg_nosec net/socket.c:706 [inline] __sock_sendmsg net/socket.c:718 [inline] ____sys_sendmsg+0x5be/0x8f0 net/socket.c:2446 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2500 __sys_sendmsg net/socket.c:2529 [inline] __do_sys_sendmsg net/socket.c:2538 [inline] __se_sys_sendmsg+0x1b7/0x2a0 net/socket.c:2536 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f220169ee99 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f21ff8d6028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f2201927090 RCX: 00007f220169ee99 RDX: 0000000000004004 RSI: 0000200000000200 RDI: 0000000000000004 RBP: 00007f2201734eaf R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f2201927128 R14: 00007f2201927090 R15: 00007ffd67e8d658