Deadlock in smb2_find_smb_tcon()

Issue

• System hang in cifs_put_smb_ses().
• System hangs with below kernel stack traces on some of the CPUs:

PID: 7823     TASK: ffff8be3b16dc000  CPU: 12   COMMAND: "cifsd"
 #0 [fffffe3822203e48] crash_nmi_callback at ffffffffb4661a93
 #1 [fffffe3822203e50] nmi_handle at ffffffffb462e1b3
 #2 [fffffe3822203ea8] default_do_nmi at ffffffffb5011d89
 #3 [fffffe3822203ec8] do_nmi at ffffffffb462e71c
 #4 [fffffe3822203ef0] end_repeat_nmi at ffffffffb5201678
    [exception RIP: native_queued_spin_lock_slowpath+0x24]
    RIP: ffffffffb475f944  RSP: ffffb55755663da0  RFLAGS: 00000202
    RAX: 0000000000000001  RBX: ffff8be448eb9400  RCX: ffff8be448eb9400
    RDX: 0000000000000001  RSI: 0000000000000001  RDI: ffffffffc10a3640  
    RBP: ffffffffc10a3640   R8: 0000000000000000   R9: ffff8be2ed680178
    R10: 0000000000000042  R11: ffff8be40911d340  R12: ffff8be2ed680000
    R13: ffffffffc102c57a  R14: ffffb55755663eb0  R15: 0000000000000000
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
--- <NMI exception stack> ---
 #5 [ffffb55755663da0] native_queued_spin_lock_slowpath at ffffffffb475f944
 #6 [ffffb55755663da0] _raw_spin_lock at ffffffffb502624e
 #7 [ffffb55755663da8] cifs_put_smb_ses at ffffffffc0fb8d17 [cifs]
 #8 [ffffb55755663de0] smb2_find_smb_tcon at ffffffffc0ff2f69 [cifs]
 #9 [ffffb55755663e00] smb2_handle_cancelled_mid at ffffffffc0ff56a2 [cifs]
#10 [ffffb55755663e20] _cifs_mid_q_entry_release at ffffffffc0fd7b57 [cifs]
#11 [ffffb55755663e38] cifs_mid_q_entry_release at ffffffffc0fd879a [cifs]
#12 [ffffb55755663e48] cifs_demultiplex_thread at ffffffffc0fb7652 [cifs]
#13 [ffffb55755663f10] kthread at ffffffffb4720ea4
#14 [ffffb55755663f50] ret_from_fork at ffffffffb52002cf


PID: 758574   TASK: ffff8be879c0c000  CPU: 0    COMMAND: "kworker/0:3"
 #0 [fffffe0fc4b80d10] machine_kexec at ffffffffb466f3d3
 #1 [fffffe0fc4b80d68] __crash_kexec at ffffffffb47bab4a
 #2 [fffffe0fc4b80e28] panic at ffffffffb46fa62f
 #3 [fffffe0fc4b80eb0] unknown_nmi_error.cold.12 at ffffffffb462e86e
 #4 [fffffe0fc4b80ec8] do_nmi at ffffffffb462e71c
 #5 [fffffe0fc4b80ef0] end_repeat_nmi at ffffffffb5201678
    [exception RIP: native_queued_spin_lock_slowpath+0x11]
    RIP: ffffffffb475f931  RSP: ffffb5574aa6bd18  RFLAGS: 00000202
    RAX: 0000000000000001  RBX: ffff8be321722800  RCX: 0000000000000000
    RDX: 0000000000000001  RSI: 0000000000000001  RDI: ffffffffc10a3630
    RBP: ffff8be321722800   R8: ffffb5574aa6bd84   R9: 0000000000000001
    R10: 0000000000000000  R11: ffff8c0100a31dc4  R12: 0000000000000000
    R13: ffff8be408ebbd40  R14: ffffb5574aa6bdf8  R15: ffff8be321722af8
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
--- <NMI exception stack> ---
 #6 [ffffb5574aa6bd18] native_queued_spin_lock_slowpath at ffffffffb475f931
 #7 [ffffb5574aa6bd18] _raw_spin_lock at ffffffffb502624e
 #8 [ffffb5574aa6bd20] smb2_get_next_mid at ffffffffc0fe8d75 [cifs]
 #9 [ffffb5574aa6bd30] smb2_setup_async_request at ffffffffc0ff3e05 [cifs]
#10 [ffffb5574aa6bd60] cifs_call_async at ffffffffc0fd950c [cifs]
#11 [ffffb5574aa6bdc8] SMB2_echo at ffffffffc0ffd8e8 [cifs]
#12 [ffffb5574aa6be68] cifs_echo_request at ffffffffc0fb44f6 [cifs]
#13 [ffffb5574aa6be90] process_one_work at ffffffffb4719663
#14 [ffffb5574aa6bed8] worker_thread at ffffffffb4719850
#15 [ffffb5574aa6bf10] kthread at ffffffffb4720ea4
#16 [ffffb5574aa6bf50] ret_from_fork at ffffffffb52002cf