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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 C8848C32789 for ; Fri, 2 Nov 2018 19:50:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 85D5B2081F for ; Fri, 2 Nov 2018 19:50:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 85D5B2081F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727145AbeKCE6n (ORCPT ); Sat, 3 Nov 2018 00:58:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44134 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726051AbeKCE6m (ORCPT ); Sat, 3 Nov 2018 00:58:42 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 92248300127F; Fri, 2 Nov 2018 19:50:13 +0000 (UTC) Received: from llong.remote.csb (dhcp-17-8.bos.redhat.com [10.18.17.8]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4A061600CD; Fri, 2 Nov 2018 19:50:12 +0000 (UTC) Subject: Re: [RFC PATCH] x86/mm/fault: Allow stack access below %rsp To: Dave Hansen , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov Cc: "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org References: <1541187610-5322-1-git-send-email-longman@redhat.com> From: Waiman Long Organization: Red Hat Message-ID: Date: Fri, 2 Nov 2018 15:50:11 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.45]); Fri, 02 Nov 2018 19:50:13 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/02/2018 03:44 PM, Dave Hansen wrote: > On 11/2/18 12:40 PM, Waiman Long wrote: >> The 64k+ limit check is kind of arbitrary. So the check is now removed >> to just let expand_stack() decide if a segmentation fault should happen. > With the 64k check removed, what's the next limit that we bump into? Is > it just the stack_guard_gap space above the next-lowest VMA? I think it is both the stack_guard_gap space above the next lowest VMA and the rlimit(RLIMIT_STACK). Cheers, Longman