syzbot

audit: type=1400 audit(1519982868.404:7): avc:  denied  { map } for  pid=4219 comm="syzkaller422792" path="/root/syzkaller422792076" dev="sda1" ino=16481 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
TCP: request_sock_TCP: Possible SYN flooding on port 20003. Sending cookies.  Check SNMP counters.

============================================
WARNING: possible recursive locking detected
4.16.0-rc3+ #335 Not tainted
--------------------------------------------
syzkaller422792/4223 is trying to acquire lock:
 (sk_lock-AF_SMC){+.+.}, at: [<0000000061eecceb>] lock_sock include/net/sock.h:1463 [inline]
 (sk_lock-AF_SMC){+.+.}, at: [<0000000061eecceb>] smc_close_non_accepted+0x1d/0x370 net/smc/af_smc.c:693

but task is already holding lock:
 (sk_lock-AF_SMC){+.+.}, at: [<000000001eb3fef6>] lock_sock include/net/sock.h:1463 [inline]
 (sk_lock-AF_SMC){+.+.}, at: [<000000001eb3fef6>] smc_close_wait_listen_clcsock net/smc/smc_close.c:47 [inline]
 (sk_lock-AF_SMC){+.+.}, at: [<000000001eb3fef6>] smc_close_active+0x8d9/0x11f0 net/smc/smc_close.c:207

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(sk_lock-AF_SMC);
  lock(sk_lock-AF_SMC);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

1 lock held by syzkaller422792/4223:
 #0:  (sk_lock-AF_SMC){+.+.}, at: [<000000001eb3fef6>] lock_sock include/net/sock.h:1463 [inline]
 #0:  (sk_lock-AF_SMC){+.+.}, at: [<000000001eb3fef6>] smc_close_wait_listen_clcsock net/smc/smc_close.c:47 [inline]
 #0:  (sk_lock-AF_SMC){+.+.}, at: [<000000001eb3fef6>] smc_close_active+0x8d9/0x11f0 net/smc/smc_close.c:207

stack backtrace:
CPU: 1 PID: 4223 Comm: syzkaller422792 Not tainted 4.16.0-rc3+ #335
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x24d lib/dump_stack.c:53
 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+0xe8f/0x3e00 kernel/locking/lockdep.c:3431
 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920
 lock_sock_nested+0xc2/0x110 net/core/sock.c:2777
 lock_sock include/net/sock.h:1463 [inline]
 smc_close_non_accepted+0x1d/0x370 net/smc/af_smc.c:693
 smc_close_cleanup_listen net/smc/smc_close.c:30 [inline]
 smc_close_active+0x9aa/0x11f0 net/smc/smc_close.c:209
 smc_release+0x379/0x580 net/smc/af_smc.c:127
 sock_release+0x8d/0x1e0 net/socket.c:595
 sock_close+0x16/0x20 net/socket.c:1149
 __fput+0x327/0x7e0 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x199/0x270 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x9bb/0x1ad0 kernel/exit.c:865
 do_group_exit+0x149/0x400 kernel/exit.c:968
 get_signal+0x73a/0x16d0 kernel/signal.c:2469
 do_signal+0x90/0x1e90 arch/x86/kernel/signal.c:809
 exit_to_usermode_loop+0x258/0x2f0 arch/x86/entry/common.c:162
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
 do_syscall_64+0x6ec/0x940 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x445659
RSP: 002b:00007f7678acbdb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00000000006dac6c