Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757178AbZA2WrX (ORCPT ); Thu, 29 Jan 2009 17:47:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751850AbZA2WrI (ORCPT ); Thu, 29 Jan 2009 17:47:08 -0500 Received: from rv-out-0506.google.com ([209.85.198.231]:44398 "EHLO rv-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752384AbZA2WrH (ORCPT ); Thu, 29 Jan 2009 17:47:07 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=OIHJNZezEQrj0KJ4qDlyVCJL51vsJ5FO1BD7n88aK3BKQI0aRuuskncpLyXadwqSwR s1Vlq1KXuKejGoycpHX0BBqUtsqqlS3yNwL/HsY5Dew151wI3Ns3SL2NrP2NDaI+Jg3O 28zydi0XRaSlMjS7z98TG//7KZ4X8URXKpWD8= MIME-Version: 1.0 In-Reply-To: References: <1233259410.2315.75.camel@lts-notebook> Date: Thu, 29 Jan 2009 14:47:05 -0800 Message-ID: Subject: Re: [PATCH] Fix OOPS in mmap_region() when merging adjacent VM_LOCKED file segments From: Maksim Yevmenkin To: Linus Torvalds Cc: Lee Schermerhorn , linux-kernel , Nick Piggin , Andrew Morton , Greg Kroah-Hartman , will@crowder-design.com, Rik van Riel , KOSAKI Motohiro , KAMEZAWA Hiroyuki Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1582 Lines: 43 On Thu, Jan 29, 2009 at 12:48 PM, Linus Torvalds wrote: > > On Thu, 29 Jan 2009, Linus Torvalds wrote: >> >> THIS PATCH IS TOTALLY UNTESTED! > > Well, it boots. FWIW. I've not really tested anything interesting with it, > but any potential breakage is at least not catastrophic and immediate. > >> diff --git a/mm/mmap.c b/mm/mmap.c >> index 8d95902..3f78ead 100644 >> --- a/mm/mmap.c >> +++ b/mm/mmap.c >> @@ -769,6 +769,10 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm, >> if (vm_flags & VM_SPECIAL) >> return NULL; >> >> + /* Anonymous shared mappings are unsharable */ >> + if ((vm_flags & VM_SHARED) && !file) >> + return NULL; >> + > > .. and I think this part of it is actually unnecessary, because what > happens is that a shared anon mapping is turned into a shmem mapping when > it is inserted, and that actually ends up allocating a file for it. So the > vma->vm_file for anon mappings will not match a NULL file pointer > _anyway_, so there's no way it would end up merging. > > So my patch can be further simplified, I think, to just the following. > Even more total lines removed. > > I still want somebody else to look at and think about it, though. Just to confirm. This patch also appear to fix the immediate issue for us. thanks, max -- 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/