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    Subject[patch 14/19] xfs: eagerly remove vmap mappings to avoid upsetting Xen
    -stable review patch.  If anyone has any objections, please let us know.

    From: Jeremy Fitzhardinge <>

    patch ace2e92e193126711cb3a83a3752b2c5b8396950 in mainline.

    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.

    [ Stable: This works around a bug in 2.6.23. We may come up with a
    better solution for mainline, but this seems like a low-impact fix for
    the stable kernel. ]

    Signed-off-by: Jeremy Fitzhardinge <>
    Cc: XFS masters <>
    Cc: Morten =?utf-8?q?B=C3=B8geskov?= <>
    Cc: Mark Williamson <>
    Signed-off-by: Greg Kroah-Hartman <>

    fs/xfs/linux-2.6/xfs_buf.c | 13 +++++++++++++
    1 file changed, 13 insertions(+)

    --- a/fs/xfs/linux-2.6/xfs_buf.c
    +++ b/fs/xfs/linux-2.6/xfs_buf.c
    @@ -187,6 +187,19 @@ free_address(
    a_list_t *aentry;

    +#ifdef CONFIG_XEN
    + /*
    + * Xen needs to be able to make sure it can get an exclusive
    + * RO mapping of pages it wants to turn into a pagetable. If
    + * a newly allocated page is also still being vmap()ed by xfs,
    + * it will cause pagetable construction to fail. This is a
    + * quick workaround to always eagerly unmap pages so that Xen
    + * is happy.
    + */
    + vunmap(addr);
    + return;
    aentry = kmalloc(sizeof(a_list_t), GFP_NOWAIT);
    if (likely(aentry)) {
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      Last update: 2007-11-15 07:25    [W:0.024 / U:3.000 seconds]
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