3.0.5-rc3: Creating HVM guest fails with: Cannot allocate memory

["Daniel P. Berrange" <berrange@redhat.com>]

I'm testing on the Xen 3.0.5 rc3 (#14934) hypervisor and userspace. On the
whole it looks pretty good - the only significant problem I seeing is that
when booting a fullyvirt guest, the Domain-0 is not being ballooned down
to make room for its memory.

[2007-04-26 18:03:31 2654] ERROR (xmlrpclib2:178) Internal error handling xend.domain.create
Traceback (most recent call last):
  File "/usr/lib64/python2.5/site-packages/xen/util/xmlrpclib2.py", line 131, in _marshaled_dispatch
    response = self._dispatch(method, params)
  File "/usr/lib64/python2.5/SimpleXMLRPCServer.py", line 415, in _dispatch
    return func(*params)
  File "/usr/lib64/python2.5/site-packages/xen/xend/server/XMLRPCServer.py", line 72, in domain_create
    info = XendDomain.instance().domain_create(config)
  File "/usr/lib64/python2.5/site-packages/xen/xend/XendDomain.py", line 914, in domain_create
    dominfo = XendDomainInfo.create(config)
  File "/usr/lib64/python2.5/site-packages/xen/xend/XendDomainInfo.py", line 81, in create
    vm.start()
  File "/usr/lib64/python2.5/site-packages/xen/xend/XendDomainInfo.py", line 395, in start
    XendTask.log_progress(0, 30, self._constructDomain)
  File "/usr/lib64/python2.5/site-packages/xen/xend/XendTask.py", line 209, in log_progress
    retval = func(*args, **kwds)
  File "/usr/lib64/python2.5/site-packages/xen/xend/XendDomainInfo.py", line 1430, in _constructDomain
    hvm = int(hvm))
Error: (12, 'Cannot allocate memory')

What is interesting is that the start() method does:

             XendTask.log_progress(0, 30, self._constructDomain)
             XendTask.log_progress(31, 60, self._initDomain)

The _constructDomain call is failing in xc.domain_create() - the code which
deals with ballooning down Domain-0 is not even run yet - that lives in
the _initDomain method. So HVM domain creation is failing before XenD has
even had a chance to do ballooning. If I manually use 'xm mem-set' to
balloon down Domain-0 ahead of time, everything works just fine.

I'm at a lose to figure out how to solve this without major re-arranging
of the order of _constructDomain & _initDomain work. Perhaps someone can
figure out an easier fix ?

This is on the x86_64 architecture and the guest config is:

name = "rhel3i386"
builder = "hvm"
memory = "500"
disk = [ 'file:/xen/rhel3i386.img,hda,w', ]
vif = [ 'type=ioemu, mac=00:16:3e:0c:e4:e3, bridge=virbr0', ]
uuid = "06017e0c-4f74-d1d0-017c-def49abd8c9c"
device_model = "/usr/lib64/xen/bin/qemu-dm"
kernel = "/usr/lib/xen/boot/hvmloader"
vnc=1
vncunused=1
apic=1
acpi=0
pae=1
vcpus=1
serial = "pty"
on_reboot   = 'restart'
on_crash    = 'restart'

The domain-0 host info is

# xm info
host                   : celery.virt.boston.redhat.com
release                : 2.6.20-2925.5.fc7ehabkosttestbuild2xen
version                : #1 SMP Thu Apr 26 16:43:56 EDT 2007
machine                : x86_64
nr_cpus                : 2
nr_nodes               : 1
sockets_per_node       : 1
cores_per_socket       : 2
threads_per_core       : 1
cpu_mhz                : 2211
hw_caps                : 178bfbff:ebd3fbff:00000000:00000010:00002001:00000000:0000001f
total_memory           : 4095
free_memory            : 0
xen_major              : 3
xen_minor              : 0
xen_extra              : .5-rc3-2925.5.f
xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 hvm-3.0-x86_32p hvm-3.0-x86_64 
xen_scheduler          : credit
xen_pagesize           : 4096
platform_params        : virt_start=0xffff800000000000
xen_changeset          : unavailable
cc_compiler            : gcc version 4.1.2 20070424 (Red Hat 4.1.2-11)
cc_compile_by          : brewbuilder
cc_compile_domain      : build.redhat.com
cc_compile_date        : Thu Apr 26 16:40:09 EDT 2007
xend_config_format     : 4

And there is nothing being reported by 'xm dmesg' when the failures
occur.

I've not had a chance to try & reproduce this on i386 yet. Hopefully will
do that tomorrrow.

Regards,
Dan.
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