From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx157.postini.com [74.125.245.157]) by kanga.kvack.org (Postfix) with SMTP id 74B7C6B0044 for ; Thu, 29 Mar 2012 22:19:58 -0400 (EDT) Date: Fri, 30 Mar 2012 03:19:45 +0100 From: Al Viro Subject: Re: [PATCH 00/16] mm: prepare for converting vm->vm_flags to 64-bit Message-ID: <20120330021945.GT6589@ZenIV.linux.org.uk> References: <20120321065140.13852.52315.stgit@zurg> <20120321100602.GA5522@barrios> <4F69D496.2040509@openvz.org> <20120322142647.42395398.akpm@linux-foundation.org> <20120322212810.GE6589@ZenIV.linux.org.uk> <4F6CA298.4000301@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4F6CA298.4000301@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org List-ID: To: KOSAKI Motohiro Cc: akpm@linux-foundation.org, khlebnikov@openvz.org, minchan@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, hughd@google.com, benh@kernel.crashing.org, linux@arm.linux.org.uk On Fri, Mar 23, 2012 at 12:19:36PM -0400, KOSAKI Motohiro wrote: > On 3/22/2012 5:28 PM, Al Viro wrote: > > On Thu, Mar 22, 2012 at 02:26:47PM -0700, Andrew Morton wrote: > >> It would be nice to find some way of triggering compiler warnings or > >> sparse warnings if someone mixes a 32-bit type with a vm_flags_t. Any > >> thoughts on this? > >> > >> (Maybe that's what __nocast does, but Documentation/sparse.txt doesn't > >> describe it) > > > > Use __bitwise for that - check how gfp_t is handled. > > Hmm.. > > If now we activate __bitwise, really plenty driver start create lots warnings. > Does it make sense? Huh? Why would they? Just adjust definitions of VM_... to include force-cast to vm_flags_t and we should be OK... > In fact, x86-32 keep 32bit vma_t forever. thus all x86 specific driver don't > need any change. Moreover many ancient drivers has no maintainer and I can't > expect such driver will be fixed even though a warning occur. What warning? If something does manual vma->vm_flags = 0xwhatever, then yes, we do want it dealt with. If it's vma->vm_flags |= VM_something, there should be no warnings at all... -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org