From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9C6CBC433DB for ; Fri, 12 Feb 2021 22:22:43 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1852464E8E for ; Fri, 12 Feb 2021 22:22:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1852464E8E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 862948D00A1; Fri, 12 Feb 2021 17:22:42 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 813168D0060; Fri, 12 Feb 2021 17:22:42 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 702958D00A1; Fri, 12 Feb 2021 17:22:42 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0083.hostedemail.com [216.40.44.83]) by kanga.kvack.org (Postfix) with ESMTP id 52EDE8D0060 for ; Fri, 12 Feb 2021 17:22:42 -0500 (EST) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 16BE8A754 for ; Fri, 12 Feb 2021 22:22:42 +0000 (UTC) X-FDA: 77811041364.14.dogs89_580afb527624 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin14.hostedemail.com (Postfix) with ESMTP id E8C1A18229996 for ; Fri, 12 Feb 2021 22:22:41 +0000 (UTC) X-HE-Tag: dogs89_580afb527624 X-Filterd-Recvd-Size: 3489 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf24.hostedemail.com (Postfix) with ESMTP for ; Fri, 12 Feb 2021 22:22:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=gcKKlfGrXCNStLb77lduw+pSfBW0G3SrA7qx+d7hHpY=; b=l+hj+dUZzkrD66BOmu9NMPhELV letFIgAorb6tgN8wQH3Ac9PqiCC5ex3XBOYsL1/hCFqpZeyP8U+ddX13otsbesapH5cmPC1PfBUNa DXugmettieUb3WZPsikow1WxhI7o5zDpRsenp1VR13gUWjlmgYKOuodH2SCpSREMPCKu7YBGHd/ij Yo1/XyFKFalI4cZ3CM70V7uH8j6ICKDB/IOcbo+QJiNkVME+BRIz8xQjfGcLNIxO21rcHD/S6xllU 5dQkfGfbDrT3YD0g//P7sEm8hkm9lmBPZsrOokpBu4ct6lly5b15a7FYeDPjYvPGcAD4YXnZR0VSI XbEuG8xw==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1lAgor-00CCXn-7e; Fri, 12 Feb 2021 22:21:45 +0000 Date: Fri, 12 Feb 2021 22:21:45 +0000 From: Matthew Wilcox To: Axel Rasmussen Cc: Alexander Viro , Alexey Dobriyan , Andrea Arcangeli , Andrew Morton , Anshuman Khandual , Catalin Marinas , Chinwen Chang , Huang Ying , Ingo Molnar , Jann Horn , Jerome Glisse , Lokesh Gidra , Michael Ellerman , Michal =?iso-8859-1?Q?Koutn=FD?= , Michel Lespinasse , Mike Kravetz , Mike Rapoport , Nicholas Piggin , Peter Xu , Shaohua Li , Shawn Anastasio , Steven Rostedt , Steven Price , Vlastimil Babka , LKML , linux-fsdevel@vger.kernel.org, Linux MM , Adam Ruprecht , Cannon Matthews , "Dr . David Alan Gilbert" , David Rientjes , Mina Almasry , Oliver Upton Subject: Re: [PATCH v5 05/10] userfaultfd: add minor fault registration mode Message-ID: <20210212222145.GB2858050@casper.infradead.org> References: <20210210212200.1097784-1-axelrasmussen@google.com> <20210210212200.1097784-6-axelrasmussen@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Feb 11, 2021 at 11:28:09AM -0800, Axel Rasmussen wrote: > Ah, I had added this just after VM_UFFD_WP, without noticing that this > would be sharing a bit with VM_LOCKED. That seems like not such a > great idea. > > I don't see another unused bit, and I don't see some other obvious > candidate to share with. So, the solution that comes to mind is it'd be even better if you didn't use the last unused bit for UFFD_WP. not sure how feasible that is, but you can see we're really short on bits here.