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Re: [Xen-devel] suspending a domain in the ngio world

> questions:
> 1)
> Does this extend as far as not being able to stop without destroying at
> all?
> I can still interact with the domain over its console.

I checked in a fix for this a couple of hours ago -- it was stopping
a domain from dying except via a forced destroy from DOM0 (e.g.,
/sbin/reboot within the domain itself wouldn't work). So a stop
request should now stop the domain. Won't be much use though as I'm
pretty sure it won't start up again happily!

> ============================================================
> 2)
> I take it that many of the following are expected right now when
> destroying a domain with I/O in flight:
> (XEN) DOM0: (file=memory.c, line=935) Unknown domain '2'
> (file=main.c, line=266) Failed MMU update transferring to DOM2

Yep, I see this. As I said: xend can just about set up a basic
interface between a guest and a device-driver backend. It's not got
functionality for tearing the interface down properly, which leaves
the backend driver in a confused state, getting you a bunch of
(fairly harmless) errors.

> [root@xen-vm0 ~]$ while (1)
> while? dd if=/dev/zero of=/tmp/bwout count=1024 bs=1024k
> while? end
> 1024+0 records in
> 1024+0 records out
> 1024+0 records in
> 1024+0 records out
> 1024+0 records in
> 1024+0 records out
> 1024+0 records in
> __alloc_pages: 0-order allocation failed (gfp=0x1d2/0)
> VM: killing process umount
> I guess memory management is a work in progress?

This is within DOM1 (i.e., not DOM0) right? If so, I guess that doing
this 'dd' test within DOM0 doesn't get you similar messages? 

This is rather unexpected -- if you could add a stack backtrace to the
out-of-memory path in the page allocator (page_alloc.c in Xenolinux)
an d post me that with the kernel image (vmlinux) then I'll see what I
can work out. I guess I haven't tested all that hard so there might be
a memory leak.

 -- Keir

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