IPVS: sync thread started: state = BACKUP, mcast_ifn = lo, syncid = 0, id = 0 IPVS: stopping backup sync thread 4617 ... IPVS: stopping backup sync thread 4616 ... ============================================ WARNING: possible recursive locking detected 4.17.0-rc2+ #14 Not tainted -------------------------------------------- syz-executor5/4576 is trying to acquire lock: (ptrval) (rtnl_mutex){+.+.}, at: rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 but task is already holding lock: (ptrval) (rtnl_mutex){+.+.}, at: rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 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 2 locks held by syz-executor5/4576: #0: (ptrval) (rtnl_mutex){+.+.}, at: rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 #1: (ptrval) (ipvs->sync_mutex){+.+.}, at: do_ip_vs_set_ctl+0x562/0x1d30 net/netfilter/ipvs/ip_vs_ctl.c:2388 stack backtrace: CPU: 1 PID: 4576 Comm: syz-executor5 Not tainted 4.17.0-rc2+ #14 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1b9/0x294 lib/dump_stack.c:113 print_deadlock_bug kernel/locking/lockdep.c:1761 [inline] check_deadlock kernel/locking/lockdep.c:1805 [inline] validate_chain kernel/locking/lockdep.c:2401 [inline] __lock_acquire.cold.62+0x18c/0x55b kernel/locking/lockdep.c:3431 lock_acquire+0x1dc/0x520 kernel/locking/lockdep.c:3920 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16d/0x17f0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 ip_mc_drop_socket+0x8f/0x270 net/ipv4/igmp.c:2643 inet_release+0x4e/0x1f0 net/ipv4/af_inet.c:413 sock_release+0x96/0x1b0 net/socket.c:594 start_sync_thread+0xdc3/0x2d40 net/netfilter/ipvs/ip_vs_sync.c:1924 do_ip_vs_set_ctl+0x59c/0x1d30 net/netfilter/ipvs/ip_vs_ctl.c:2389 nf_sockopt net/netfilter/nf_sockopt.c:106 [inline] nf_setsockopt+0x7d/0xd0 net/netfilter/nf_sockopt.c:115 ip_setsockopt+0xd8/0xf0 net/ipv4/ip_sockglue.c:1253 tcp_setsockopt+0x93/0xe0 net/ipv4/tcp.c:2890 sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:3039 __sys_setsockopt+0x1bd/0x390 net/socket.c:1903 __do_sys_setsockopt net/socket.c:1914 [inline] __se_sys_setsockopt net/socket.c:1911 [inline] __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1911 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x455389 RSP: 002b:00007fe8d48c6c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 00007fe8d48c76d4 RCX: 0000000000455389 RDX: 000000000000048b RSI: 0000000000000000 RDI: 0000000000000004 RBP: 000000000072bea0 R08: 0000000000000018 R09: 0000000000000000 R10: 0000000020000040 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000529 R14: 00000000006fac78 R15: 0000000000000000 IPVS: stopping backup sync thread 4604 ... IPVS: stopping backup sync thread 4603 ...