Unfortunately that doesn't narrow down what the kernel was actually trying to do at the time. Clearly a set_pte; looks like someone is trying to create a writable mapping of an existing pte page.
Does "console=hvc0 earlyprintk=xen" on the kernel command line give any clue about how far it gets before crashing?
Console is already hvc0, but earlyprintk gets us:
--8<-----------------------------------------------------------------
Reserving virtual address space above 0xf57fe000
Linux version 2.6.25-rc2-bisectme (jlbec@xxxxxxxxxxxxxxxxxxxxxxxx) (gcc
version 4.1.2 20070626 (Red Hat 4.1.2-14)) #21 SMP Fri Feb 15 16:28:35
PST 2008
ACPI in unprivileged domain disabled
BIOS-provided physical RAM map:
Xen: 0000000000000000 - 0000000078000000 (usable)
console [xenboot0] enabled
1192MB HIGHMEM available.
727MB LOWMEM available.
Started domain ca-test58
Scan SMP from c0000000 for 1024 bytes.
Scan SMP from c009fc00 for 1024 bytes.
Scan SMP from c00f0000 for 65536 bytes.
NX (Execute Disable) protection: active
Zone PFN ranges:
DMA 0 -> 4096
Normal 4096 -> 186366
HighMem 186366 -> 491520
Movable zone start PFN for each node
early_node_map[1] active PFN ranges
0: 0 -> 491520
-->8-----------------------------------------------------------------
That's it.