port-mips/55062: Failed assertion in pmap_md_tlb_check_entry()

[thorpej%me.com@localhost]

>Number:         55062
>Category:       port-mips
>Synopsis:       Failed assertion in pmap_md_tlb_check_entry()
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    port-mips-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Mar 10 01:35:00 +0000 2020
>Originator:     Jason Thorpe
>Release:        NetBSD 9.99.48
>Organization:
Riscy Business
>Environment:
NetBSD cobalt 9.99.48 NetBSD 9.99.48 (GENERIC)
>Description:
I am occasionally having the following panic:

kernel diagnostic assertion \"pte == xpte\" failed: file \"../../../../arch/mips/mips/pmap_machdep.c\", line 871 pmap=0x80641be4 va=0xc3018000 asid=0: TLB pte (0x7e01f) != real pte (0x1/0x1) @ 0x80712

It doesn't happen frequently, but in a bit over a week it's happened 4 times.
>How-To-Repeat:
No readily reproducible case.

>Fix:
N/A