From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755092AbYFAHyT (ORCPT ); Sun, 1 Jun 2008 03:54:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751333AbYFAHyH (ORCPT ); Sun, 1 Jun 2008 03:54:07 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:59228 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751323AbYFAHyF (ORCPT ); Sun, 1 Jun 2008 03:54:05 -0400 Date: Sun, 1 Jun 2008 00:53:38 -0700 From: Andrew Morton To: Jiri Kosina Cc: Geert Uytterhoeven , Ingo Molnar , Linux/m68k , Linux Kernel Development Subject: Re: m68k libc5 regression Message-Id: <20080601005338.3affe880.akpm@linux-foundation.org> In-Reply-To: References: X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.5; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 27 May 2008 00:19:32 +0200 (CEST) Jiri Kosina wrote: > On Mon, 26 May 2008, Geert Uytterhoeven wrote: > > > Recently I noticed a regression when running an old libc5 binary > > (amiga-lilo) on m68k. It fails with the error message: > > Hmm, libc5 is known to make broken assumptions about brk location, that's > why we introduced CONFIG_COMPAT_BRK, do you have that option turned on? > > > So I bisected it to: > > commit 4cc6028d4040f95cdb590a87db478b42b8be0508 > > Author: Jiri Kosina > > Date: Wed Feb 6 22:39:44 2008 +0100 > > brk: check the lower bound properly > > Indeed, this should take CONFIG_COMPAT_BRK into account. Does the patch > below fix it? (assuming that you have CONFIG_COMPAT_BRK=y): > > > > From: Jiri Kosina > > brk: check lower bound properly > > The check in sys_brk() on minimum value the brk might have must take > CONFIG_COMPAT_BRK setting into account. When this option is turned on > (i.e. we support ancient legacy binaries, e.g. libc5-linked stuff), the > lower bound on brk value is mm->end_code, otherwise the brk start is > allowed to be arbitrarily shifted. > > Signed-off-by: Jiri Kosina > > diff --git a/mm/mmap.c b/mm/mmap.c > index fac6633..834118b 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -245,10 +245,16 @@ asmlinkage unsigned long sys_brk(unsigned long brk) > unsigned long rlim, retval; > unsigned long newbrk, oldbrk; > struct mm_struct *mm = current->mm; > + unsigned long min_brk; > > down_write(&mm->mmap_sem); > > - if (brk < mm->start_brk) > +#ifdef CONFIG_COMPAT_BRK > + min_brk = mm->end_code; > +#else > + min_brk = mm->start_brk; > +#endif > + if (brk < min_brk) > goto out; > OK, we have a problem here. Somebody has gone and checked this patch into their tree and it now appears in linux-next. I do not know how to work out how this patch got into linux-next. It's not in any of the trees which I pull so I guess that person has been shuffling URLs without telling me. One of the reasons this is bad is that, frankly, I trust almost nobody to remember to backport fixes into 2.6.25.x. I'm not even at all confident that our mystery new part-time memory management maintainer will remember to merge this into 2.6.26. The fact that this person failed to add a Cc:stable@kernel.org to the changelog doesn't inspire confidence. I shall merge this fix into my tree (y'know - the one where memory management patches are hosted) and I'll get it into 2.6.26 and shall offer it to the -stable team. This will cause me to get collisions with the duplicated patch in linux-next but fortunately it is small. This time. And to whoever did this: please don't.