Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751342Ab1FPEgK (ORCPT ); Thu, 16 Jun 2011 00:36:10 -0400 Received: from rcsinet10.oracle.com ([148.87.113.121]:34791 "EHLO rcsinet10.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750731Ab1FPEgH (ORCPT ); Thu, 16 Jun 2011 00:36:07 -0400 Date: Wed, 15 Jun 2011 21:35:49 -0700 From: Randy Dunlap To: Linux Kernel Mailing List , akpm Cc: torvalds , Michal Hocko Subject: Re: fs/exec.c: use BUILD_BUG_ON for VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP Message-Id: <20110615213549.9b399976.randy.dunlap@oracle.com> In-Reply-To: <201106160359.p5G3x3j4020081@hera.kernel.org> References: <201106160359.p5G3x3j4020081@hera.kernel.org> Organization: Oracle Linux Eng. X-Mailer: Sylpheed 2.7.1 (GTK+ 2.16.6; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Source-IP: rtcsinet21.oracle.com [66.248.204.29] X-CT-RefId: str=0001.0A090208.4DF98830.0095:SCFSTAT5015188,ss=1,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2354 Lines: 60 On Thu, 16 Jun 2011 03:59:03 GMT Linux Kernel Mailing List wrote: > Gitweb: http://git.kernel.org/linus/7f81c8890c15a10f5220bebae3b6dfae4961962a > Commit: 7f81c8890c15a10f5220bebae3b6dfae4961962a > Parent: b0825ee3a8c570df4873ee397fa453e67fdad5d7 > Author: Michal Hocko > AuthorDate: Wed Jun 15 15:08:11 2011 -0700 > Committer: Linus Torvalds > CommitDate: Wed Jun 15 20:03:59 2011 -0700 > > fs/exec.c: use BUILD_BUG_ON for VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP > > Commit a8bef8ff6ea1 ("mm: migration: avoid race between shift_arg_pages() > and rmap_walk() during migration by not migrating temporary stacks") > introduced a BUG_ON() to ensure that VM_STACK_FLAGS and > VM_STACK_INCOMPLETE_SETUP do not overlap. The check is a compile time > one, so BUILD_BUG_ON is more appropriate. > > Signed-off-by: Michal Hocko > Cc: Mel Gorman > Signed-off-by: Andrew Morton > Signed-off-by: Linus Torvalds fwiw, I just reported that this causes a build error in UML on x86_64 in mmotm-2011-06-15: When building UML for x86_64 (defconfig), I get: fs/built-in.o: In function `__bprm_mm_init': mmotm-2011-0615-1656/fs/exec.c:280: undefined reference to `__build_bug_on_failed' > --- > fs/exec.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/fs/exec.c b/fs/exec.c > index 97e0d52..b54f74f 100644 > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -277,7 +277,7 @@ static int __bprm_mm_init(struct linux_binprm *bprm) > * use STACK_TOP because that can depend on attributes which aren't > * configured yet. > */ > - BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP); > + BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP); > vma->vm_end = STACK_TOP_MAX; > vma->vm_start = vma->vm_end - PAGE_SIZE; > vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP; > -- --- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code *** -- 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/