From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f198.google.com (mail-wr0-f198.google.com [209.85.128.198]) by kanga.kvack.org (Postfix) with ESMTP id 04FA46B0033 for ; Thu, 14 Dec 2017 09:54:48 -0500 (EST) Received: by mail-wr0-f198.google.com with SMTP id m6so3359424wrf.1 for ; Thu, 14 Dec 2017 06:54:47 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id q3sor2102878wrd.74.2017.12.14.06.54.46 for (Google Transport Security); Thu, 14 Dec 2017 06:54:46 -0800 (PST) Date: Thu, 14 Dec 2017 14:54:43 +0000 From: Edward Napierala Subject: Re: [PATCH v2 0/2] mm: introduce MAP_FIXED_SAFE Message-ID: <20171214145443.GA2202@brick> References: <20171213092550.2774-1-mhocko@kernel.org> <20171213163210.6a16ccf8753b74a6982ef5b6@linux-foundation.org> <20171214131526.GM16951@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171214131526.GM16951@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Andrew Morton , linux-api@vger.kernel.org, Khalid Aziz , Michael Ellerman , Russell King - ARM Linux , Andrea Arcangeli , linux-mm@kvack.org, LKML , linux-arch@vger.kernel.org, Florian Weimer , John Hubbard , Matthew Wilcox , Abdul Haleem , Joel Stanley , Kees Cook , jasone@google.com, davidtgoldblatt@gmail.com On 1214T1415, Michal Hocko wrote: > On Thu 14-12-17 12:44:17, Edward Napierala wrote: > > Regarding the name - how about adopting MAP_EXCL? It was introduced in > > FreeBSD, > > and seems to do exactly this; quoting mmap(2): > > > > MAP_FIXED Do not permit the system to select a different address > > than the one specified. If the specified address > > cannot be used, mmap() will fail. If MAP_FIXED is > > specified, addr must be a multiple of the page size. > > If MAP_EXCL is not specified, a successful MAP_FIXED > > request replaces any previous mappings for the > > process' pages in the range from addr to addr + len. > > In contrast, if MAP_EXCL is specified, the request > > will fail if a mapping already exists within the > > range. > > I am not familiar with the FreeBSD implementation but from the above it > looks like MAP_EXCL is a MAP_FIXED mofifier which is not how we are > going to implement it in linux due to reasons mentioned in this cover > letter. Using the same name would be more confusing than helpful I am > afraid. Sorry, missed that. Indeed, reusing a name with a different semantics would be a bad idea. -- 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