System got hung due to deadlock condition over the ssb_state lock

Issue

• On certain AMD CPUs if hyper-threading is enabled, systems can encounter a deadlock condition over the ssb_state lock.

crash> bt
PID: 17848  TASK: ffff96290579e2a0  CPU: 0   COMMAND: "clojure-agent-s"
 #0 [ffff96293fc08cf0] machine_kexec at ffffffff94265b34
 #1 [ffff96293fc08d50] __crash_kexec at ffffffff94322592
 #2 [ffff96293fc08e20] panic at ffffffff94974a16
 #3 [ffff96293fc08ea0] nmi_panic at ffffffff9429b80f
 #4 [ffff96293fc08eb0] do_nmi at ffffffff94985df6
 #5 [ffff96293fc08ef0] end_repeat_nmi at ffffffff94984d9c
    [exception RIP: native_queued_spin_lock_slowpath+29]
    RIP: ffffffff9431757d  RSP: ffff9625be4efc38  RFLAGS: 00000093
    RAX: 0000000000000001  RBX: 0000000000000400  RCX: 0000000000000001
    RDX: 0000000000000001  RSI: 0000000000000001  RDI: ffff96293fc10d78
    RBP: ffff9625be4efc38   R8: 0000000000000001   R9: 0000000000000001
    R10: 0000000000000001  R11: 0000000000000304  R12: ffff96293fc10d70
    R13: 0000000000000000  R14: ffffffff94e18480  R15: ffff96290579e2a0
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
--- <NMI exception stack> ---
 #6 [ffff9625be4efc38] native_queued_spin_lock_slowpath at ffffffff9431757d
 #7 [ffff9625be4efc40] queued_spin_lock_slowpath at ffffffff949754ee
 #8 [ffff9625be4efc50] _raw_spin_lock at ffffffff94983b20
 #9 [ffff9625be4efc60] __switch_to_xtra at ffffffff942378bd
#10 [ffff9625be4efca8] __switch_to at ffffffff9422b981
#11 [ffff9625be4efd00] __schedule at ffffffff94980d4a
#12 [ffff9625be4efd98] schedule at ffffffff949811f9
#13 [ffff9625be4efda8] schedule_timeout at ffffffff9497ed01
#14 [ffff9625be4efe58] wait_for_completion_killable at ffffffff94981f61
#15 [ffff9625be4efec0] do_fork at ffffffff9429abe9
#16 [ffff9625be4eff38] sys_vfork at ffffffff9429adfc
#17 [ffff9625be4eff48] stub_vfork at ffffffff9498e394
#18 [ffff9625be4eff50] system_call_fastpath at ffffffff9498dede
    RIP: 00007f327264769c  RSP: 00007f3145eeb570  RFLAGS: 00000293
    RAX: 000000000000003a  RBX: 00007f3194002a60  RCX: ffffffffffffffff
    RDX: 00000000ffffbd4a  RSI: 00000000000042b6  RDI: 00007f326bde9841
    RBP: 00007f3145eeb590   R8: 0000000000000000   R9: 00007f3271d90cf0
    R10: 2d00636e79732d6f  R11: 0000000000000293  R12: 00007f31a800fdd0
    R13: 00007f31a80181b0  R14: 00007f31a8015eb0  R15: 00007f31a8016060
    ORIG_RAX: 000000000000003a  CS: 0033  SS: 002b