From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-5.7 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI,SPF_HELO_NONE,SPF_NONE autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 4CB6C7D2EF for ; Tue, 11 Jun 2019 07:24:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404294AbfFKHY1 (ORCPT ); Tue, 11 Jun 2019 03:24:27 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39522 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404260AbfFKHY0 (ORCPT ); Tue, 11 Jun 2019 03:24:26 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 425D6C18B2F3; Tue, 11 Jun 2019 07:24:20 +0000 (UTC) Received: from oldenburg2.str.redhat.com (ovpn-116-118.ams2.redhat.com [10.36.116.118]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4F4B05D721; Tue, 11 Jun 2019 07:24:04 +0000 (UTC) From: Florian Weimer To: Dave Hansen Cc: Yu-cheng Yu , Andy Lutomirski , Peter Zijlstra , x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin Subject: Re: [PATCH v7 03/14] x86/cet/ibt: Add IBT legacy code bitmap setup function References: <20190606200926.4029-1-yu-cheng.yu@intel.com> <20190606200926.4029-4-yu-cheng.yu@intel.com> <20190607080832.GT3419@hirez.programming.kicks-ass.net> <20190607174336.GM3436@hirez.programming.kicks-ass.net> <34E0D316-552A-401C-ABAA-5584B5BC98C5@amacapital.net> <7e0b97bf1fbe6ff20653a8e4e147c6285cc5552d.camel@intel.com> <25281DB3-FCE4-40C2-BADB-B3B05C5F8DD3@amacapital.net> <3f19582d-78b1-5849-ffd0-53e8ca747c0d@intel.com> <5aa98999b1343f34828414b74261201886ec4591.camel@intel.com> <0665416d-9999-b394-df17-f2a5e1408130@intel.com> <5c8727dde9653402eea97bfdd030c479d1e8dd99.camel@intel.com> <328275c9b43c06809c9937c83d25126a6e3efcbd.camel@intel.com> <92e56b28-0cd4-e3f4-867b-639d9b98b86c@intel.com> Date: Tue, 11 Jun 2019 09:24:03 +0200 In-Reply-To: <92e56b28-0cd4-e3f4-867b-639d9b98b86c@intel.com> (Dave Hansen's message of "Mon, 10 Jun 2019 15:02:45 -0700") Message-ID: <8736kgd1po.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Tue, 11 Jun 2019 07:24:26 +0000 (UTC) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org * Dave Hansen: > My assumption has always been that these large, potentially sparse > hardware tables *must* be mmap()'d with MAP_NORESERVE specified. That > should keep them from being problematic with respect to overcommit. MAP_NORESERVE pages still count towards the commit limit. The flag only disables checks at allocation time, for this particular allocation. (At least this was the behavior the last time I looked into this, I believe.) Not sure if this makes a difference here. Thanks, Florian