======================================================
[ INFO: possible circular locking dependency detected ]
4.9.113-g47bbcd6 #10 Not tainted
-------------------------------------------------------
syz-executor4/10044 is trying to acquire lock:
 (rtnl_mutex){+.+.+.}, at: [<ffffffff830b5937>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
but task is already holding lock:
 (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff83346939>] lock_sock include/net/sock.h:1404 [inline]
 (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff83346939>] do_ip_setsockopt.isra.13+0x269/0x2b10 net/ipv4/ip_sockglue.c:636
which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

       lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
       lock_sock_nested+0xc6/0x120 net/core/sock.c:2511
       lock_sock include/net/sock.h:1404 [inline]
       set_mcast_if net/netfilter/ipvs/ip_vs_sync.c:1370 [inline]
       make_send_sock net/netfilter/ipvs/ip_vs_sync.c:1490 [inline]
       start_sync_thread+0x88b/0x1e80 net/netfilter/ipvs/ip_vs_sync.c:1885
       do_ip_vs_set_ctl+0x7c8/0xc00 net/netfilter/ipvs/ip_vs_ctl.c:2398
       nf_sockopt net/netfilter/nf_sockopt.c:105 [inline]
       nf_setsockopt+0x6d/0xc0 net/netfilter/nf_sockopt.c:114
       ip_setsockopt+0x9a/0xb0 net/ipv4/ip_sockglue.c:1247
       udp_setsockopt+0x4a/0x90 net/ipv4/udp.c:2091
       sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:2706
       SYSC_setsockopt net/socket.c:1772 [inline]
       SyS_setsockopt+0x166/0x260 net/socket.c:1751
       do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
       entry_SYSCALL_64_after_swapgs+0x5d/0xdb

       check_prev_add kernel/locking/lockdep.c:1828 [inline]
       check_prevs_add kernel/locking/lockdep.c:1938 [inline]
       validate_chain kernel/locking/lockdep.c:2265 [inline]
       __lock_acquire+0x3019/0x4070 kernel/locking/lockdep.c:3345
       lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
       __mutex_lock_common kernel/locking/mutex.c:521 [inline]
       mutex_lock_nested+0xc0/0x870 kernel/locking/mutex.c:621
       rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
       mrtsock_destruct+0x3b/0x1e0 net/ipv4/ipmr.c:1231
       ip_ra_control+0x2c2/0x420 net/ipv4/ip_sockglue.c:360
       do_ip_setsockopt.isra.13+0x15ff/0x2b10 net/ipv4/ip_sockglue.c:1137
       ip_setsockopt+0x3a/0xb0 net/ipv4/ip_sockglue.c:1240
       raw_setsockopt+0xb7/0xd0 net/ipv4/raw.c:833
       sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:2706
       SYSC_setsockopt net/socket.c:1772 [inline]
       SyS_setsockopt+0x166/0x260 net/socket.c:1751
       do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
       entry_SYSCALL_64_after_swapgs+0x5d/0xdb

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sk_lock-AF_INET);
                               lock(rtnl_mutex);
                               lock(sk_lock-AF_INET);
  lock(rtnl_mutex);

 *** DEADLOCK ***

1 lock held by syz-executor4/10044:
 #0:  (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff83346939>] lock_sock include/net/sock.h:1404 [inline]
 #0:  (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff83346939>] do_ip_setsockopt.isra.13+0x269/0x2b10 net/ipv4/ip_sockglue.c:636

stack backtrace:
CPU: 1 PID: 10044 Comm: syz-executor4 Not tainted 4.9.113-g47bbcd6 #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d3fa75f8 ffffffff81eb32a9 ffffffff8559d0a0 ffffffff855e7800
 ffffffff8559d0a0 ffff88019e3e08e8 ffff88019e3e0000 ffff8801d3fa7640
 ffffffff81426404 0000000000000001 000000009e3e0000 0000000000000001
Call Trace:
 [<ffffffff81eb32a9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb32a9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81426404>] print_circular_bug.cold.51+0x1bd/0x27d kernel/locking/lockdep.c:1202
 [<ffffffff812391c9>] check_prev_add kernel/locking/lockdep.c:1828 [inline]
 [<ffffffff812391c9>] check_prevs_add kernel/locking/lockdep.c:1938 [inline]
 [<ffffffff812391c9>] validate_chain kernel/locking/lockdep.c:2265 [inline]
 [<ffffffff812391c9>] __lock_acquire+0x3019/0x4070 kernel/locking/lockdep.c:3345
 [<ffffffff8123ac90>] lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
 [<ffffffff839ef240>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
 [<ffffffff839ef240>] mutex_lock_nested+0xc0/0x870 kernel/locking/mutex.c:621
 [<ffffffff830b5937>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 [<ffffffff83485f6b>] mrtsock_destruct+0x3b/0x1e0 net/ipv4/ipmr.c:1231
 [<ffffffff83346572>] ip_ra_control+0x2c2/0x420 net/ipv4/ip_sockglue.c:360
 [<ffffffff83347ccf>] do_ip_setsockopt.isra.13+0x15ff/0x2b10 net/ipv4/ip_sockglue.c:1137
 [<ffffffff8334921a>] ip_setsockopt+0x3a/0xb0 net/ipv4/ip_sockglue.c:1240
 [<ffffffff833eb2e7>] raw_setsockopt+0xb7/0xd0 net/ipv4/raw.c:833
 [<ffffffff8301d75a>] sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:2706
 [<ffffffff8301a516>] SYSC_setsockopt net/socket.c:1772 [inline]
 [<ffffffff8301a516>] SyS_setsockopt+0x166/0x260 net/socket.c:1751
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f9f93>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
9pnet: p9_fd_create_tcp (10220): problem connecting socket to 127.0.0.1
9pnet: p9_fd_create_tcp (10220): problem connecting socket to 127.0.0.1