Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753811AbYFWXIZ (ORCPT ); Mon, 23 Jun 2008 19:08:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753400AbYFWXHO (ORCPT ); Mon, 23 Jun 2008 19:07:14 -0400 Received: from mx2.suse.de ([195.135.220.15]:39089 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752610AbYFWXHN (ORCPT ); Mon, 23 Jun 2008 19:07:13 -0400 Date: Mon, 23 Jun 2008 16:04:52 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , Willy Tarreau , Rodrigo Rubira Branco , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk Subject: [patch 10/10] Fix ZERO_PAGE breakage with vmware Message-ID: <20080623230452.GD29853@suse.de> References: <20080623225737.837265824@mini.kroah.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline; filename="fix-zero_page-breakage-with-vmware.patch" In-Reply-To: <20080623230417.GA29853@suse.de> User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2934 Lines: 89 2.6.25.9-stable review patch. If anyone has any objections, please let us know. Note, I had to merge this patch by hand, can someone verify that I didn't mess it up? ------------------ From: Linus Torvalds commit 672ca28e300c17bf8d792a2a7a8631193e580c74 upstream Commit 89f5b7da2a6bad2e84670422ab8192382a5aeb9f ("Reinstate ZERO_PAGE optimization in 'get_user_pages()' and fix XIP") broke vmware, as reported by Jeff Chua: "This broke vmware 6.0.4. Jun 22 14:53:03.845: vmx| NOT_IMPLEMENTED /build/mts/release/bora-93057/bora/vmx/main/vmmonPosix.c:774" and the reason seems to be that there's an old bug in how we handle do FOLL_ANON on VM_SHARED areas in get_user_pages(), but since it only triggered if the whole page table was missing, nobody had apparently hit it before. The recent changes to 'follow_page()' made the FOLL_ANON logic trigger not just for whole missing page tables, but for individual pages as well, and exposed this problem. This fixes it by making the test for when FOLL_ANON is used more careful, and also makes the code easier to read and understand by moving the logic to a separate inline function. Reported-and-tested-by: Jeff Chua Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/memory.c | 24 +++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-) --- a/mm/memory.c +++ b/mm/memory.c @@ -989,6 +989,26 @@ no_page_table: return page; } +/* Can we do the FOLL_ANON optimization? */ +static inline int use_zero_page(struct vm_area_struct *vma) +{ + /* + * We don't want to optimize FOLL_ANON for make_pages_present() + * when it tries to page in a VM_LOCKED region. As to VM_SHARED, + * we want to get the page from the page tables to make sure + * that we serialize and update with any other user of that + * mapping. + */ + if (vma->vm_flags & (VM_LOCKED | VM_SHARED)) + return 0; + /* + * And if we have a fault or a nopfn routine, it's not an + * anonymous region. + */ + return !vma->vm_ops || + (!vma->vm_ops->fault && !vma->vm_ops->nopfn); +} + int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, int len, int write, int force, struct page **pages, struct vm_area_struct **vmas) @@ -1063,9 +1083,7 @@ int get_user_pages(struct task_struct *t foll_flags = FOLL_TOUCH; if (pages) foll_flags |= FOLL_GET; - if (!write && !(vma->vm_flags & VM_LOCKED) && - (!vma->vm_ops || (!vma->vm_ops->nopage && - !vma->vm_ops->fault))) + if (!write && use_zero_page(vma)) foll_flags |= FOLL_ANON; do { -- -- 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/