From: Jeremy Fitzhardinge Date: Wed, 17 Oct 2007 03:55:03 +0000 (+1000) Subject: [XFS] eagerly remove vmap mappings to avoid upsetting Xen X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=7f015072348a14f16d548be557ee58c5c55df0aa;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git [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 Signed-off-by: David Chinner Signed-off-by: Tim Shimmin --- diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c index 8d9298c99763..d5b2d2bbf5ff 100644 --- 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; +#endif + aentry = kmalloc(sizeof(a_list_t), GFP_NOWAIT); if (likely(aentry)) { spin_lock(&as_lock);