Comment 2 for bug 164904

As additional info, here is the git commit:
commit 7f015072348a14f16d548be557ee58c5c55df0aa
Author: Jeremy Fitzhardinge <email address hidden>
Date: Wed Oct 17 13:55:03 2007 +1000

    [XFS] eagerly remove vmap mappings to avoid upsetting Xen

    XFS leaves stray mappings around when it vmaps memory to make it virtually
    contigious. This upsets Xen if one of those pages is being recycled into a
    pagetable, since it finds an extra writable mapping of the page.

    This patch solves the problem in a brute force way, by making XFS always
    eagerly unmap its mappings.

    SGI-PV: 971902
    SGI-Modid: xfs-linux-melb:xfs-kern:29886a

    Signed-off-by: Jeremy Fitzhardinge <email address hidden>
    Signed-off-by: David Chinner <email address hidden>
    Signed-off-by: Tim Shimmin <email address hidden>