kern/53059: "nvmectl identify nvme0" locks up system

[kardel%netbsd.org@localhost]

>Number:         53059
>Category:       kern
>Synopsis:       repeated nvmectl identify nvme0 locks up sytem
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Feb 27 11:50:00 +0000 2018
>Originator:     Frank Kardel
>Release:        NetBSD 8.99.12-20180224180000
>Organization:
	
>Environment:
	
	
System: NetBSD pip.kardel.name 8.99.12 NetBSD 8.99.12 (PIPGEN) #10: Sat Feb 24 19:26:44 CET 2018 kardel@xxx:/src/NetBSD/act/src/obj.amd64/sys/arch/amd64/compile/PIPGEN amd64
Architecture: x86_64
Machine: amd64
>Description:
	repeated invocation of "nvmectl identify nvme0" (about 45-50 times) will
	lock up the system hard. for the more relaxed people - smartd takes about
	22:30h to lock up the system.
	If you are lucky yousee the panic: nvme0: invalid ccb detected triggerted
	via softint_dispatch()->nvme_poll().
	needless to say: breaking into DDB via USB attached keyboards does not work here.

>How-To-Repeat:
	csh(as root): repeat 64 nvmectl identify nvme0
>Fix:
	no fix - check for admin q depletion - it is close to the limit of admin q entries.

>Unformatted: