kern/56617: assertion "!samepage" failed

[prlw1%cam.ac.uk@localhost]

>Number:         56617
>Category:       kern
>Synopsis:       assertion "!samepage" failed
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jan 11 17:00:00 +0000 2022
>Originator:     Patrick Welche
>Release:        NetBSD-9.99.93/amd64 of 10 Jan 2022
>Organization:
>Environment:
>Description:
Laptop was under load running a simulation. Opened firefox while waiting
and hit this panic:

panic: kernel diagnostic assertion "!samepage" failed: file "../../../../arch/x86/x86/pmap.c", line 5020 
cpu0: Begin traceback...
vpanic() at netbsd:vpanic+0x14a
kern_assert() at netbsd:kern_assert+0x4b
pmap_enter_ma() at netbsd:pmap_enter_ma+0xb27
pmap_enter_default() at netbsd:pmap_enter_default+0x29
uvm_fault_internal() at netbsd:uvm_fault_internal+0x167a
trap() at netbsd:trap+0x1b4
--- trap (number 6) ---
7f7fe06f6c50:
cpu0: End traceback...

dumping to dev 168,5 (offset=33942087, size=4145847):
dump succeeded


Kernel lock error: _kernel_lock,239: spinout

lock address : 0xffffffff8105b380 type     :               spin
initialized  : 0xffffffff80a68020
shared holds :                  0 exclusive:                  0
shares wanted:                  0 exclusive:                  0
relevant cpu :                  2 last held:                  0
relevant lwp : 0xffffa45f7e7b22c0 last held: 000000000000000000
last locked  : 0xffffffff8043f0ac unlocked*: 0xffffffff8043f0c2
curcpu holds :                  0 wanted by: 0xffffa45f7e7b22c0

rebooting...

(gdb) target kvm netbsd.0.core
0xffffffff80222765 in cpu_reboot (howto=howto@entry=260, 
    bootstr=bootstr@entry=0x0) at ../../../../arch/amd64/amd64/machdep.c:720
720                     dumpsys();
(gdb) bt
#0  0xffffffff80222765 in cpu_reboot (howto=howto@entry=260, 
    bootstr=bootstr@entry=0x0) at ../../../../arch/amd64/amd64/machdep.c:720
#1  0xffffffff808cd967 in kern_reboot (howto=howto@entry=260, 
    bootstr=bootstr@entry=0x0) at ../../../../kern/kern_reboot.c:73
#2  0xffffffff80912a3a in vpanic (
    fmt=0xffffffff80d8d008 "kernel %sassertion \"%s\" failed: file \"%s\", line %d ", ap=ap@entry=0xffffb2814ff1ca88) at ../../../../kern/subr_prf.c:290
#3  0xffffffff80a67f17 in kern_assert (
    fmt=fmt@entry=0xffffffff80d8d008 "kernel %sassertion \"%s\" failed: file \"%s\", line %d ") at ../../../../../../lib/libkern/kern_assert.c:51
#4  0xffffffff8044de89 in pmap_enter_ma (pmap=0xffffa45fa60a1400, 
    va=va@entry=140187202957312, ma=<optimized out>, pa=5229785088, 
    prot=prot@entry=5, flags=flags@entry=32, domid=domid@entry=0)
    at ../../../../arch/x86/x86/pmap.c:5020
#5  0xffffffff8044e0d2 in pmap_enter_default (pmap=<optimized out>, 
    va=va@entry=140187202957312, pa=<optimized out>, prot=prot@entry=5, 
    flags=flags@entry=32) at ../../../../arch/x86/x86/pmap.c:4788
#6  0xffffffff80869ca5 in uvm_fault_lower_neighbor (pg=0xffffb28000c86f80, 
    currva=140187202957312, flt=0xffffb2814ff1cc98, ufi=0xffffb2814ff1cc60)
    at ../../../../uvm/uvm_fault.c:2097
#7  uvm_fault_lower_lookup (pages=0xffffb2814ff1cd50, flt=0xffffb2814ff1cc98, 
    ufi=0xffffb2814ff1cc60) at ../../../../uvm/uvm_fault.c:2035
#8  uvm_fault_lower (pages=0xffffb2814ff1cd50, flt=0xffffb2814ff1cc98, 
    ufi=0xffffb2814ff1cc60) at ../../../../uvm/uvm_fault.c:1873
#9  uvm_fault_internal (orig_map=orig_map@entry=0xffffa45f80ab29e0, 
    vaddr=vaddr@entry=140187202969600, access_type=access_type@entry=4, 
    fault_flag=fault_flag@entry=0) at ../../../../uvm/uvm_fault.c:942
#10 0xffffffff80224bd6 in trap (frame=0xffffb2814ff1cf00)
    at ../../../../arch/amd64/amd64/trap.c:520
#11 0xffffffff8021da8d in alltraps ()
#12 0x00007f7fe9f7dc28 in ?? ()
#13 0x00007f7ff13c3640 in ?? ()
#14 0x0000000000000018 in ?? ()
#15 0x0000000000000000 in ?? ()
(gdb) frame 7
#7  uvm_fault_lower_lookup (pages=0xffffb2814ff1cd50, flt=0xffffb2814ff1cc98, 
    ufi=0xffffb2814ff1cc60) at ../../../../uvm/uvm_fault.c:2035
2035                            uvm_fault_lower_neighbor(ufi, flt, currva, curpg);
(gdb) print *ufi
$1 = {orig_map = 0xffffa45f80ab29e0, orig_rvaddr = 140187202969600, 
  orig_size = 4096, map = 0xffffa45f80ab29e0, mapv = 25555, 
  entry = 0xffffa45faa5fac40, size = 4096}
(gdb) print *flt
$2 = {access_type = 4, startva = 140187202957312, npages = 8, centeridx = 3, 
  narrow = true, wire_mapping = false, wire_paging = false, cow_now = false, 
  enter_prot = 5, anon_spare = 0x0, promote = false, 
  lower_lock_type = RW_READER, upper_lock_type = RW_READER}

(note to self: /usr/obj/crash/netbsd.0.core)
>How-To-Repeat:
Nothing obvious
>Fix: