Something

leaf9 login: BUG: unable to handle kernel NULL pointer dereference at virtual address 00000004
 printing eip:
*pde = 1199a001
*pte = 00000000
Oops: 0002 [#1]
SMP 
Modules linked in: kvm_xen kvm nfsd exportfs sctp ipv6 nfs lockd nfs_acl sunrpc bridge dm_snapshot pcspkr ext3 jbd sg sd_mod mptsas mptscsih mptbase scsi_transport_sas scsi_mod ehci_hcd uhci_hcd bnx2 dm_mod
CPU:    0
EIP:    0060:[<c0448222>]    Not tainted VLI
EFLAGS: 00010282   (2.6.20 #4)
EIP is at __free_pages+0x3/0x20
eax: 00000000   ebx: d1462e80   ecx: 00000000   edx: 00000004
esi: fffffff4   edi: c8c18000   ebp: ffc11000   esp: d1462e4c
ds: 007b   es: 007b   ss: 0068
Process qemu (pid: 4072, ti=d1462000 task=c14bdaa0 task.ti=d1462000)
Stack: e117864a e117ab07 00000001 00000006 e1186100 d1458464 00000012 c8c18000 
       e117824e d1462ef8 00000000 c8c17000 00000010 c11180e0 c1118100 c1118120 
       c1118140 c1118160 c1118180 c11181a0 c11181c0 c11181e0 c1118200 c1118220 
Call Trace:
 [<e117864a>] lg_init+0x159/0x1a7 [kvm_xen]
 [<e117824e>] xen_vcpu_create+0xa0/0xd5 [kvm_xen]
 [<e1168ee6>] kvm_vm_ioctl+0x89/0x585 [kvm]
 [<c04aedb4>] inode_has_perm+0x5b/0x63
 [<c04aee45>] file_has_perm+0x89/0x91
 [<c0452ffb>] do_mmap_pgoff+0x57a/0x6e3
 [<e1168e5d>] kvm_vm_ioctl+0x0/0x585 [kvm]
 [<c0469247>] do_ioctl+0x1f/0x62
 [<c04694ce>] vfs_ioctl+0x244/0x256
 [<c046952c>] sys_ioctl+0x4c/0x64
 [<c0402c6c>] sysenter_past_esp+0x5d/0x81
 =======================
Code: 00 00 00 8b 54 24 14 8b 74 24 18 f7 d2 21 fa 46 89 d0 29 f8 89 d7 c1 e0 05 01 c5 e9 63 ff ff ff 83 c4 1c 5b 5e 5f 5d c3 89 c1 90 <ff> 48 04 0f 94 c0 84 c0 74 12 85 d2 75 07 89 c8 e9 a5 fd ff ff 
EIP: [<c0448222>] __free_pages+0x3/0x20 SS:ESP 0068:d1462e4c