kern/57020: kernel diagnostic assertion "!RB_SENTINEL_P(tree->rbt_root)" failed: file "/home/riastradh/netbsd/current/src/sys/arch/x86/x86/pmap.c", line 2261

[campbell+netbsd%mumble.net@localhost]

>Number:         57020
>Category:       kern
>Synopsis:       kernel diagnostic assertion "!RB_SENTINEL_P(tree->rbt_root)" failed: file "/home/riastradh/netbsd/current/src/sys/arch/x86/x86/pmap.c", line 2261
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Sep 24 06:50:00 +0000 2022
>Originator:     Taylor R Campbell
>Release:        current
>Organization:
The pmapBSD Foundation
>Environment:
NetBSD singbulli 9.99.100 NetBSD 9.99.100 (GENERIC) #38: Fri Sep 23 17:56:58 UTC 2022  root@singbulli:/home/riastradh/netbsd/current/obj.amd64/sys/arch/amd64/compile/GENERIC amd64
>Description:
System panicked: kernel diagnostic assertion "!RB_SENTINEL_P(tree->rbt_root)" failed: file "/home/riastradh/netbsd/current/src/sys/arch/x86/x86/pmap.c", line 2261 

kern_reboot() at sys_reboot
vpanic() at vpanic+0x18d
kern_assert() at __x86_indirect_thunk_rax
pmap_lookup_pv() at pmap_lookup_pv+0xc1
pmap_remove_pte() at pmap_remove_pte+0x12a
pmap_remove() at pmap_remove+0x189
uvm_unmap_remove() at uvm_unmap_remove+0x292
sys_munmap() at sys_munmap+0x9e
syscall() at syscall+0x196
--- syscall (number 73) ---

Process was X.  rbtree for ptp is empty:

(gdb) print ptp->mdpage.mp_pp.pp_u.rb
$8 = {rbt_root = 0x0, rbt_ops = 0xffffffff8123d2c0 <pmap_rbtree_ops>,
  rbt_minmax = {0x0, 0x0}}

Crash dump available.
>How-To-Repeat:
unsure -- possibly related to new x86 efi runtime logic, which touches pmap, but that seems unlikely because it doesn't have anything to do with pv tracking or ptp data structures
>Fix:
Yes, please!