Dom0 ballooning: crash on guest start

[Christoph Egger <Christoph_Egger%gmx.de@localhost>]

Hi,

When I start xenstored, xenconsoled and xenbackendd
the kernel prints this:

balloon0 at xenbus0 id 0: Xen Balloon driver
balloon0: current reservation: 8157904 KiB
balloon0: WARNING: power management not supported
balloon0: error, couldn't read xenbus target node

The machine has indeed 8GB RAM.

Then when I start a HVM guest the balloon driver crashes:

balloon0: current reservation: 2039476 pages => target: 2039476 pages
balloon0: current reservation: 2039476 pages => target: 981172 pages
uvm_fault(0xffffffff80c6b220, 0xffffffff81400000, 1) -> e
fatal page fault in supervisor mode
trap type 6 code 0 rip ffffffff8054584d cs e030 rflags 10216 cr2 
ffffffff81400000 cpl 0 rsp ffffa00057ca8a50
kernel: page fault trap, code=0
Stopped in pid 0.58 (system) at netbsd:pmap_zero_page+0x41:     movq 
0(%rax,%
rbx,8),%rbx
pmap_zero_page() at netbsd:pmap_zero_page+0x41
uvm_pagealloc_strat() at netbsd:uvm_pagealloc_strat+0x22d
bpge_ctor() at netbsd:bpge_ctor+0x22
pool_cache_get_slow() at netbsd:pool_cache_get_slow+0x1df
pool_cache_get_paddr() at netbsd:pool_cache_get_paddr+0x1f7
balloon_thread() at netbsd:balloon_thread+0x379
ds          0
es          0x1032
fs          0x7680
gs          0
rdi         0xbbe00000
rsi         0xffffffff80cec1c0  ld_prime+0x1860
rbp         0xffffa00057ca8a80
rbx         0xbbe00
rdx         0xffffffff80bcfec8  cpu_info_primary+0x188
rcx         0
rax         0xffffffff80e21000
r8          0xffffa0000f215f00
r9          0xffffa000055838c0
r10         0
r11         0
r12         0
r13         0x7fd000000010
r14         0
r15         0
rip         0xffffffff8054584d  pmap_zero_page+0x41
cs          0xe030
rflags      0x10216
rsp         0xffffa00057ca8a50
ss          0xe02b
netbsd:pmap_zero_page+0x41:     movq    0(%rax,%rbx,8),%rbx