On Thu, 15 Feb 2007 18:25:00 -0800 Jeremy Fitzhardinge <jeremy at goop.org> wrote: > Add a new mm function apply_to_page_range() which applies a given > function to every pte in a given virtual address range in a given mm > structure. This is a generic alternative to cut-and-pasting the Linux > idiomatic pagetable walking code in every place that a sequence of > PTEs must be accessed. > > Although this interface is intended to be useful in a wide range of > situations, it is currently used specifically by several Xen > subsystems, for example: to ensure that pagetables have been allocated > for a virtual address range, and to construct batched special > pagetable update requests to map I/O memory (in ioremap()). There was some discussion about this sort of thing last week. The consensus was that it's better to run the callback against a whole pmd's worth of ptes, mainly to amortise the callback's cost (a lot). It was implemented in ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.20/2.6.20-mm1/broken-out/smaps-extract-pmd-walker-from-smaps-code.patch
