From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id BD1A26B005A for ; Wed, 2 Sep 2009 04:34:56 -0400 (EDT) From: Arnd Bergmann Subject: Re: [PATCH 2/3] Add MAP_HUGETLB for mmaping pseudo-anonymous huge page regions Date: Wed, 2 Sep 2009 10:34:40 +0200 References: <20090901130801.GB7995@us.ibm.com> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <200909021034.40827.arnd@arndb.de> Sender: owner-linux-mm@kvack.org To: Hugh Dickins Cc: Eric B Munson , Mel Gorman , linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, linux-man@vger.kernel.org, Michael Kerrisk , randy.dunlap@oracle.com List-ID: On Tuesday 01 September 2009, Hugh Dickins wrote: > On Tue, 1 Sep 2009, Eric B Munson wrote: > > On Tue, 01 Sep 2009, Hugh Dickins wrote: > > > > > > That is explained by you #defining MAP_HUGETLB in include/asm-generic/ > > > mman-common.h to a number which is already being used for other MAP_s > > > on some architectures. That's a separate bug which needs to be fixed > > > by distributing the MAP_HUGETLB definition across various asm*/mman.h. > > > > Would it be okay to keep the define in include/asm-generic/mman.h > > if a value that is known free across all architectures is used? > > 0x080000 is not used by any arch and, AFAICT would work just as well. > > That's a very sensible suggestion, but departs from how we have > assigned new numbers up until now: so include/asm-generic/mman-common.h > isn't actually where we'd expect to find a Linux-specific MAP_ define. > > I'd say, yes, do that for now, so as not to hit this conflict while > testing in mmotm. But whether it should stay that way, or later the > arch/*/include/asm/mman.h's be updated as I'd imagined, I don't know. > > Arnd, Michael, do you have any views on this? The minimal procedure would be to add it to mman-common.h, plus the asm/mman.h files for xtensa, mips, parisc and alpha, which all use a version that is compatible to a Unix variant, but that would be confusing the next person that needs to add a flag. I'd use the number 0x40000 for all architectures except alpha, because that makes the most sense for asm-generic/mman.h. Alpha is weird anyway here, so we don't need to avoid conflicts with it. With a few exceptions (sparc, powerpc), I think we should change all architectures to use asm-generic/mman.h instead of mman-common.h in the long run. If you touch those anyway, one option would be to do it in one step. Arnd <>< -- 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/ . Don't email: email@kvack.org