1/3 is not a bugfix in itself, but a pre-requisite for 2/3.
2/3 replaces an ad-hoc Xen fix with a general fix to prevent address
truncation when using PFN_PHYS() on any PFN above the 4G mark. The Xen
crash is the only bug I know of that's directly attributable to this,
and it was already addressed in older kernels with the casts in the Xen
code that this patch removes.
So I don't think there's any strong need to push this to earlier kernels.
J
--