From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263818AbTE3QpU (ORCPT ); Fri, 30 May 2003 12:45:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263823AbTE3QpU (ORCPT ); Fri, 30 May 2003 12:45:20 -0400 Received: from e31.co.us.ibm.com ([32.97.110.129]:39049 "EHLO e31.co.us.ibm.com") by vger.kernel.org with ESMTP id S263818AbTE3QpL (ORCPT ); Fri, 30 May 2003 12:45:11 -0400 Date: Thu, 29 May 2003 19:38:26 -0700 From: "Paul E. McKenney" To: Hugh Dickins Cc: phillips@arcor.de, akpm@digeo.com, hch@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC][PATCH] Avoid vmtruncate/mmap-page-fault race Message-ID: <20030530023826.GA1350@us.ibm.com> Reply-To: paulmck@us.ibm.com References: <20030529151424.GA1397@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 29, 2003 at 05:33:04PM +0100, Hugh Dickins wrote: > On Thu, 29 May 2003, Paul E. McKenney wrote: > > On Fri, May 23, 2003 at 11:42:02AM -0700, Paul E. McKenney wrote: > > > > > > Exactly -- allows a ->nopage() to drop some lock to avoid races > > > between pagefault and either vmtruncate() or invalidate_mmap_range(). > > > This race (from the cross-host mmap viewpoint) is described in: > > > > > > http://marc.theaimsgroup.com/?l=linux-kernel&m=105286345316249&w=2 > > > > Rediffed for 2.5.70-mm1. > > Me? I much preferred your original, much sparer, nopagedone patch > (labelled "uglyh as hell" by hch). I dislike passing lots of args > down a level so they can be passed up again to the library function. > > In particular, I feel queasy (fear loss of control) about passing a > pmd_t* down to a filesystem, which I'd prefer to have no access to > such. But I may be in a minority, and the decision won't be mine. Fine by me either way. ;-) Here is the rediffed nopagedone patch for 2.5.70-mm1. Thanx, Paul diff -urN -X dontdiff linux-2.5.70-mm1/include/linux/mm.h linux-2.5.70-mm1.nopagedone/include/linux/mm.h --- linux-2.5.70-mm1/include/linux/mm.h 2003-05-28 20:16:04.000000000 -0700 +++ linux-2.5.70-mm1.nopagedone/include/linux/mm.h 2003-05-29 19:34:55.000000000 -0700 @@ -143,6 +143,7 @@ void (*open)(struct vm_area_struct * area); void (*close)(struct vm_area_struct * area); struct page * (*nopage)(struct vm_area_struct * area, unsigned long address, int unused); + void (*nopagedone)(struct vm_area_struct * area, unsigned long address, int status); int (*populate)(struct vm_area_struct * area, unsigned long address, unsigned long len, pgprot_t prot, unsigned long pgoff, int nonblock); }; diff -urN -X dontdiff linux-2.5.70-mm1/mm/memory.c linux-2.5.70-mm1.nopagedone/mm/memory.c --- linux-2.5.70-mm1/mm/memory.c 2003-05-28 20:16:04.000000000 -0700 +++ linux-2.5.70-mm1.nopagedone/mm/memory.c 2003-05-29 19:34:55.000000000 -0700 @@ -1468,6 +1468,9 @@ ret = VM_FAULT_OOM; out: pte_chain_free(pte_chain); + if (vma->vm_ops && vma->vm_ops->nopagedone) { + vma->vm_ops->nopagedone(vma, address & PAGE_MASK, ret); + } return ret; }