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. David Chinner says this shouldn't have any performance impact on filesystems with default block sizes; it will only affect filesystems with large block sizes. Signed-off-by: Jeremy Fitzhardinge Cc: David Chinner Cc: Nick Piggin Cc: XFS masters Cc: Stable kernel Cc: Morten =?utf-8?q?B=C3=B8geskov?= Cc: Mark Williamson --- 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 @@ -186,6 +186,19 @@ free_address( void *addr) { 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; +#endif aentry = kmalloc(sizeof(a_list_t), GFP_NOWAIT); if (likely(aentry)) { -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/