======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.1.3587/17147 is trying to acquire lock:
ffff888119ba96b0 ((work_completion)(&new_smc->smc_listen_work)){+.+.}-{0:0}, at: __flush_work+0xd2/0xbc0

but task is already holding lock:
ffff888119ba8258 (sk_lock-AF_SMC/1){+.+.}-{0:0}, at: smc_release+0x255/0x540

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (sk_lock-AF_SMC/1){+.+.}-{0:0}:
       lock_acquire+0x120/0x360
       lock_sock_nested+0x48/0x100
       smc_listen_out+0x109/0x3e0
       process_scheduled_works+0xae1/0x17b0
       worker_thread+0x8a0/0xda0
       kthread+0x711/0x8a0
       ret_from_fork+0x3fc/0x770
       ret_from_fork_asm+0x1a/0x30

-> #0 ((work_completion)(&new_smc->smc_listen_work)){+.+.}-{0:0}:
       validate_chain+0xb9b/0x2140
       __lock_acquire+0xab9/0xd20
       lock_acquire+0x120/0x360
       __flush_work+0x6b8/0xbc0
       __cancel_work_sync+0xbe/0x110
       smc_clcsock_release+0x60/0xf0
       __smc_release+0x66b/0x7e0
       smc_close_non_accepted+0xd5/0x1f0
       smc_close_active+0xb68/0xf10
       __smc_release+0x8d/0x7e0
       smc_release+0x2ce/0x540
       sock_close+0xc3/0x240
       __fput+0x44c/0xa70
       task_work_run+0x1d4/0x260
       exit_to_user_mode_loop+0xec/0x110
       do_syscall_64+0x2bd/0x3b0
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sk_lock-AF_SMC/1);
                               lock((work_completion)(&new_smc->smc_listen_work));
                               lock(sk_lock-AF_SMC/1);
  lock((work_completion)(&new_smc->smc_listen_work));

 *** DEADLOCK ***

3 locks held by syz.1.3587/17147:
 #0: ffff88802a45d008 (&sb->s_type->i_mutex_key#11){+.+.}-{4:4}, at: sock_close+0x9b/0x240
 #1: ffff888119ba8258 (sk_lock-AF_SMC/1){+.+.}-{0:0}, at: smc_release+0x255/0x540
 #2: ffffffff8e139ea0 (rcu_read_lock){....}-{1:3}, at: __flush_work+0xd2/0xbc0

stack backtrace:
CPU: 1 UID: 0 PID: 17147 Comm: syz.1.3587 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250
 print_circular_bug+0x2ee/0x310
 check_noncircular+0x134/0x160
 validate_chain+0xb9b/0x2140
 __lock_acquire+0xab9/0xd20
 lock_acquire+0x120/0x360
 __flush_work+0x6b8/0xbc0
 __cancel_work_sync+0xbe/0x110
 smc_clcsock_release+0x60/0xf0
 __smc_release+0x66b/0x7e0
 smc_close_non_accepted+0xd5/0x1f0
 smc_close_active+0xb68/0xf10
 __smc_release+0x8d/0x7e0
 smc_release+0x2ce/0x540
 sock_close+0xc3/0x240
 __fput+0x44c/0xa70
 task_work_run+0x1d4/0x260
 exit_to_user_mode_loop+0xec/0x110
 do_syscall_64+0x2bd/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f73da58ebe9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f73db399038 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f73da7b5fa0 RCX: 00007f73da58ebe9
RDX: 0000000000000000 RSI: ffffffffffffffff RDI: 0000000000000003
RBP: 00007f73da611e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f73da7b6038 R14: 00007f73da7b5fa0 R15: 00007ffd63d044e8
 </TASK>
