From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752109AbXC1IE2 (ORCPT ); Wed, 28 Mar 2007 04:04:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752674AbXC1IE2 (ORCPT ); Wed, 28 Mar 2007 04:04:28 -0400 Received: from smtp105.mail.mud.yahoo.com ([209.191.85.215]:28613 "HELO smtp105.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752109AbXC1IE0 (ORCPT ); Wed, 28 Mar 2007 04:04:26 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:X-YMail-OSG:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=Qx2AX1BQA2CAOP6xHIn2lGpP8PuSlLZAhuRI16H1pxItGBQYpGqQ+TRjgc2Vwngg3aBVu4ygu6qoYnyFY4mHuWjSjLlkBsCU8sw3Mrsy9HTmEMdux1WzyIR5/jVne3BQHraYIY18gByJf6zGSaWahtsj5Emlw5ra546bc0v7TQ8= ; X-YMail-OSG: A8Mzfz8VM1n0ooSSXRF0gkUprGyFJtib.qp98oLGgD9wRQ_O57jhM41UspCFzrnpZxN3dpxSRVVNQ.8WLynOZC720kIxvC4vTgmBBSKVoW_5Cd.DI3U- Message-ID: <460A2184.8060207@yahoo.com.au> Date: Wed, 28 Mar 2007 18:04:20 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051007 Debian/1.7.12-1 X-Accept-Language: en MIME-Version: 1.0 To: Pekka J Enberg CC: akpm@linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] revoke: break cow for private mappings References: In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Pekka J Enberg wrote: > From: Pekka Enberg > > We need to break COW for private mappings to make sure a process cannot > read new data after an inode has been revoked. Seems OK. > > Signed-off-by: Pekka Enberg > --- > fs/revoke.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++++++--------- > 1 file changed, 73 insertions(+), 12 deletions(-) > > Index: uml-2.6/fs/revoke.c > =================================================================== > --- uml-2.6.orig/fs/revoke.c 2007-03-26 18:10:24.000000000 +0300 > +++ uml-2.6/fs/revoke.c 2007-03-26 18:27:25.000000000 +0300 > @@ -174,12 +174,58 @@ static inline bool need_revoke(struct vm > if (file->f_path.dentry->d_inode != inode) > return false; > > - if (!(vma->vm_flags & VM_SHARED)) > - return false; > - > return file != to_exclude; > } > > +static int __revoke_break_cow(struct task_struct *tsk, struct inode *inode, > + struct file *to_exclude) > +{ > + struct mm_struct *mm = tsk->mm; > + struct vm_area_struct *vma; > + int err = 0; > + > + down_write(&mm->mmap_sem); > + for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) { > + int ret; > + > + if (vma->vm_flags & VM_SHARED) > + continue; > + > + if (!need_revoke(vma, inode, to_exclude)) > + continue; > + > + ret = get_user_pages(tsk, tsk->mm, vma->vm_start, > + vma->vm_end-vma->vm_start, 1, 1, NULL, > + NULL); get_user_pages length argument is in # of pages, rather than address range, I think. vma_pages is what you want? > + if (ret < 0) { > + err = ret; > + break; > + } > + } > + up_write(&mm->mmap_sem); I think you just need down_read of mmap_sem here? -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com