Re: Using disk image from NFS crashes kernel

[Roger Pau Monné <roger.pau%entel.upc.edu@localhost>]

> please set ddb.onpanic to 1 and get a stack trace from here.
> The traceback from panic doesn't look very reliable ...

Sorry about that, I've forgot to get the full traceback:

panic: kernel diagnostic assertion "pg != NULL" failed: file
"/usr/src/sys/uvm/uvm_pager.c", line 489
fatal breakpoint trap in supervisor mode
trap type 1 code 0 rip ffffffff8021579d cs e030 rflags 246 cr2
ffffa0002ad94754 cpl 0 rsp ffffa0002b0cb9f0
Stopped in pid 0.54 (system) at netbsd:breakpoint+0x5:  leave
breakpoint() at netbsd:breakpoint+0x5
panic() at netbsd:panic+0x28c
kern_assert() at netbsd:kern_assert+0x2d
uvm_pageratop() at netbsd:uvm_pageratop+0x7e
nfs_doio() at netbsd:nfs_doio+0x1f9
nfssvc_iod() at netbsd:nfssvc_iod+0x17b
ds          aff0
es          fc99
fs          b9d0
gs          62c1
rdi         0
rsi         deadbeef
rbp         ffffa0002b0cb9f0
rbx         ffffa0002b0cba00
rdx         0
rcx         8
rax         1
r8          ffffffff80be49c0    cpu_info_primary
r9          0
r10         ffffa0002b0cb910
r11         1
r12         104
r13         ffffffff80acaff0    __link_set_malloc_types_sym_M_PROP_ARRAY+0x59200

r14         1
r15         ffffa0002d47fc60
rip         ffffffff8021579d    breakpoint+0x5
cs          e030
rflags      246
rsp         ffffa0002b0cb9f0
ss          e02b
netbsd:breakpoint+0x5:  leave

>> My kernel version is 5.99.52, and I'm running xen-unstable (although I
>> think this bug is not related to xen itself).
>
> It's probably not related to Xen, but I'd recommend trying a newer
> -current kernel.

I think it's the same problem as the one reported by Christoph Egger
on PR #40726, and AFAIK it seems like it's not solved. Also the vnd(4)
man page states that "The vnd driver does not work if the file does
not reside in a local filesystem.", which is a problem if the user
wants to perform live migrations between NetBSD Dom0 Xen servers. I
don't know how how to fix this, but I think it is important to have
this feature.

Thanks, Roger.