From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761032AbXJLVrc (ORCPT ); Fri, 12 Oct 2007 17:47:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758134AbXJLVom (ORCPT ); Fri, 12 Oct 2007 17:44:42 -0400 Received: from 224.sub-75-208-255.myvzw.com ([75.208.255.224]:42271 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1760415AbXJLVoj (ORCPT ); Fri, 12 Oct 2007 17:44:39 -0400 Message-Id: <20071012211148.864500000@goop.org> References: <20071012211132.198718000@goop.org> User-Agent: quilt/0.46-1 Date: Fri, 12 Oct 2007 14:11:42 -0700 From: Jeremy Fitzhardinge To: LKML Cc: Andi Kleen , Andrew Morton , virtualization@lists.osdl.org, xen-devel@lists.xensource.com, Chris Wright , Keir Fraser , XFS masters , Stable kernel , Morten =?utf-8?q?B=C3=B8geskov?= , Mark Williamson Subject: [PATCH 10/10] xfs: eagerly remove vmap mappings to avoid upsetting Xen Content-Disposition: inline; filename=xen-xfs-unmap.patch Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org 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: 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)) { --