IPv6: ADDRCONF(NETDEV_UP): veth1_to_batadv: link is not ready
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
======================================================
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0
WARNING: possible circular locking dependency detected
4.14.282-syzkaller #0 Not tainted
------------------------------------------------------
kworker/u4:0/5 is trying to acquire lock:
 ((&(&cp->cp_send_w)->work)){+.+.}, at: [<ffffffff81367a68>] flush_work+0x88/0x770 kernel/workqueue.c:2887

but task is already holding lock:
 (k-sk_lock-AF_INET){+.+.}, at: [<ffffffff869ca021>] lock_sock include/net/sock.h:1473 [inline]
 (k-sk_lock-AF_INET){+.+.}, at: [<ffffffff869ca021>] rds_tcp_reset_callbacks+0x181/0x450 net/rds/tcp.c:165

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (k-sk_lock-AF_INET){+.+.}:
       lock_sock_nested+0xb7/0x100 net/core/sock.c:2813
       lock_sock include/net/sock.h:1473 [inline]
       do_tcp_setsockopt.constprop.0+0xfb/0x1c10 net/ipv4/tcp.c:2564
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
       tcp_setsockopt net/ipv4/tcp.c:2832 [inline]
       tcp_setsockopt+0xa7/0xc0 net/ipv4/tcp.c:2824
       kernel_setsockopt+0xfb/0x1b0 net/socket.c:3396
       rds_tcp_cork net/rds/tcp_send.c:43 [inline]
       rds_tcp_xmit_path_prepare+0xaf/0xe0 net/rds/tcp_send.c:50
       rds_send_xmit+0x1ae/0x1c00 net/rds/send.c:187
       rds_send_worker+0x6d/0x240 net/rds/threads.c:189
       process_one_work+0x793/0x14a0 kernel/workqueue.c:2117
       worker_thread+0x5cc/0xff0 kernel/workqueue.c:2251
       kthread+0x30d/0x420 kernel/kthread.c:232
       ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

-> #0 ((&(&cp->cp_send_w)->work)){+.+.}:
       lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
       flush_work+0xad/0x770 kernel/workqueue.c:2890
       __cancel_work_timer+0x321/0x460 kernel/workqueue.c:2965
       rds_tcp_reset_callbacks+0x18d/0x450 net/rds/tcp.c:167
       rds_tcp_accept_one+0x61a/0x8b0 net/rds/tcp_listen.c:194
       rds_tcp_accept_worker+0x4d/0x70 net/rds/tcp.c:407
       process_one_work+0x793/0x14a0 kernel/workqueue.c:2117
       worker_thread+0x5cc/0xff0 kernel/workqueue.c:2251
       kthread+0x30d/0x420 kernel/kthread.c:232
       ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(k-sk_lock-AF_INET);
                               lock((&(&cp->cp_send_w)->work));
                               lock(k-sk_lock-AF_INET);
  lock((&(&cp->cp_send_w)->work));

 *** DEADLOCK ***

4 locks held by kworker/u4:0/5:
 #0:  ("%s""krdsd"){+.+.}, at: [<ffffffff81364f80>] process_one_work+0x6b0/0x14a0 kernel/workqueue.c:2088
 #1:  ((&rtn->rds_tcp_accept_w)){+.+.}, at: [<ffffffff81364fb6>] process_one_work+0x6e6/0x14a0 kernel/workqueue.c:2092
 #2:  (&tc->t_conn_path_lock){+.+.}, at: [<ffffffff869cbe12>] rds_tcp_accept_one+0x502/0x8b0 net/rds/tcp_listen.c:186
 #3:  (k-sk_lock-AF_INET){+.+.}, at: [<ffffffff869ca021>] lock_sock include/net/sock.h:1473 [inline]
 #3:  (k-sk_lock-AF_INET){+.+.}, at: [<ffffffff869ca021>] rds_tcp_reset_callbacks+0x181/0x450 net/rds/tcp.c:165

stack backtrace:
CPU: 1 PID: 5 Comm: kworker/u4:0 Not tainted 4.14.282-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: krdsd rds_tcp_accept_worker
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1258
 check_prev_add kernel/locking/lockdep.c:1905 [inline]
 check_prevs_add kernel/locking/lockdep.c:2022 [inline]
 validate_chain kernel/locking/lockdep.c:2464 [inline]
 __lock_acquire+0x2e0e/0x3f20 kernel/locking/lockdep.c:3491
 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
 flush_work+0xad/0x770 kernel/workqueue.c:2890
 __cancel_work_timer+0x321/0x460 kernel/workqueue.c:2965
 rds_tcp_reset_callbacks+0x18d/0x450 net/rds/tcp.c:167
 rds_tcp_accept_one+0x61a/0x8b0 net/rds/tcp_listen.c:194
 rds_tcp_accept_worker+0x4d/0x70 net/rds/tcp.c:407
 process_one_work+0x793/0x14a0 kernel/workqueue.c:2117
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2251
 kthread+0x30d/0x420 kernel/kthread.c:232
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
IPv6: ADDRCONF(NETDEV_UP): batadv_slave_0: link is not ready
batman_adv: batadv0: Interface activated: batadv_slave_0
IPv6: ADDRCONF(NETDEV_CHANGE): macsec0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): macvtap0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): macsec0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_batadv: link becomes ready
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
IPv6: ADDRCONF(NETDEV_UP): batadv_slave_0: link is not ready
batman_adv: batadv0: Interface activated: batadv_slave_0
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
IPv6: ADDRCONF(NETDEV_UP): batadv_slave_1: link is not ready
batman_adv: batadv0: Interface activated: batadv_slave_1
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_batadv: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
IPv6: ADDRCONF(NETDEV_UP): batadv_slave_1: link is not ready
batman_adv: batadv0: Interface activated: batadv_slave_1
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready