======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.3550/20141 is trying to acquire lock:
ffff88801e433c68 ((work_completion)(&new_smc->smc_listen_work)){+.+.}-{0:0}, at: __flush_work+0x101/0xca0

but task is already holding lock:
ffff8881be488260 (sk_lock-AF_SMC/1){+.+.}-{0:0}, at: smc_release+0x24d/0x550

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_sock_nested+0x41/0x100
       smc_listen_out+0xd4/0x3d0
       smc_listen_work+0x81d/0x1410
       process_scheduled_works+0xa88/0x14c0
       worker_thread+0xa47/0xfb0
       kthread+0x38b/0x480
       ret_from_fork+0x514/0xb70
       ret_from_fork_asm+0x1a/0x30

-> #0 ((work_completion)(&new_smc->smc_listen_work)){+.+.}-{0:0}:
       __lock_acquire+0x1520/0x2cf0
       lock_acquire+0x106/0x350
       __flush_work+0x74c/0xca0
       __cancel_work_sync+0xbf/0x110
       smc_clcsock_release+0x60/0xf0
       __smc_release+0x64e/0x7c0
       smc_close_non_accepted+0xd5/0x1f0
       smc_close_active+0xb42/0xf30
       __smc_release+0x9c/0x7c0
       smc_release+0x2c5/0x550
       __sock_release+0xa0/0x1f0
       sock_close+0x1c/0x30
       __fput+0x418/0xa50
       task_work_run+0x1d9/0x270
       exit_to_user_mode_loop+0x204/0x770
       do_syscall_64+0x328/0x520
       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 ***

locks held by syz.0.3550/20141: 3, last CPU#0:
 #0: ffff8881ba39e240 (&sb->s_type->i_mutex_key#13){+.+.}-{4:4}, at: __sock_release+0x7a/0x1f0
 #1: ffff8881be488260 (sk_lock-AF_SMC/1){+.+.}-{0:0}, at: smc_release+0x24d/0x550
 #2: ffffffff8eb5a1e0 (rcu_read_lock){....}-{1:3}, at: __flush_work+0x101/0xca0

stack backtrace:
CPU: 0 UID: 0 PID: 20141 Comm: syz.0.3550 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+0xe8/0x150
 print_circular_bug+0x2e1/0x300
 check_noncircular+0x12e/0x150
 __lock_acquire+0x1520/0x2cf0
 lock_acquire+0x106/0x350
 __flush_work+0x74c/0xca0
 __cancel_work_sync+0xbf/0x110
 smc_clcsock_release+0x60/0xf0
 __smc_release+0x64e/0x7c0
 smc_close_non_accepted+0xd5/0x1f0
 smc_close_active+0xb42/0xf30
 __smc_release+0x9c/0x7c0
 smc_release+0x2c5/0x550
 __sock_release+0xa0/0x1f0
 sock_close+0x1c/0x30
 __fput+0x418/0xa50
 task_work_run+0x1d9/0x270
 exit_to_user_mode_loop+0x204/0x770
 do_syscall_64+0x328/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb87239e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd0dd8b4d8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007ffd0dd8b5c0 RCX: 00007fb87239e0d9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00000000000a2caf R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b31220000 R11: 0000000000000246 R12: 00007ffd0dd8b600
R13: 00007fb872625fac R14: 00000000000a2f43 R15: 00007fb872625fa0
 </TASK>
