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=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED 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 A6E19C04ABB for ; Tue, 11 Sep 2018 18:20:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 454B820866 for ; Tue, 11 Sep 2018 18:20:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="M+kQ3ESa" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 454B820866 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org 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 S1728040AbeIKXVR (ORCPT ); Tue, 11 Sep 2018 19:21:17 -0400 Received: from mail-io0-f194.google.com ([209.85.223.194]:40160 "EHLO mail-io0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726818AbeIKXVQ (ORCPT ); Tue, 11 Sep 2018 19:21:16 -0400 Received: by mail-io0-f194.google.com with SMTP id l14-v6so4359489iob.7 for ; Tue, 11 Sep 2018 11:20:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=L8PWVi64V+HXxYaawqOWuD8gu2wOwwGDM6U615liPUo=; b=M+kQ3ESaIuAdQrMpX3rL9UE0/78JGJ1tyB3JU5WWNT29XHOJYX1HN7s73bUk3K9C/1 TkrBNXd1SVprZR2mTA7VnTJLcc705uVEUcVPfZeJN2P9ZhZigqBF3CmGORlwooXU1g4P 7Mtly+RdoIyDKrTV01WSO/tKQLEY5tVzvvtMU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=L8PWVi64V+HXxYaawqOWuD8gu2wOwwGDM6U615liPUo=; b=QHd3rUZwl5Wszb/qEk0W/93YCUsYdpIP3/+kbAmBNHAfp6sL1OW7i9Jc7VAHPmU6Kw E/9OoQX5QhNW4CTYMvLNiQjnFFKKVYmFrLrQ7AupO+UWxEIU1kDlRS7bAjLScixF2alx 3IKyyD6bfWcQGxHuhuWWvWYuO+CeimKWYpPI4VlQSQSVTafGn4/biGW4ymnwFNu8VU89 HgPYpaYDsyGd75kq5S8HoEd6cQVEJ8zyZA34jHztnDtsy7PurrnTBwZZ2i750ubE7Gpf 59cqEZIRWZOIL6czVtxYs3PO7Cv1Cz7ZMEqQPpVIau6TJDfSp4Kthn3AXxvSV/3Vcpm4 TVDA== X-Gm-Message-State: APzg51DH58OMb1HguX3TjM9YleDrgmN5y3GUieVuAO6GzG30I4IyrFNR fhXQ+PahmALpJV3RaMybq3NWFoRFdKOyFXtm+W8= X-Google-Smtp-Source: ANB0VdYMGtoEBJAmkBUj9J0nNfXXW+4dmqynl871RzyvXPoVmZRnvMkHgXUp6F2JWAgu8aOQDUso3KsDBbuEDwh5cYA= X-Received: by 2002:a6b:f609:: with SMTP id n9-v6mr23952143ioh.259.1536690045391; Tue, 11 Sep 2018 11:20:45 -0700 (PDT) MIME-Version: 1.0 References: <20180830205527.dmemjwxfbwvkdzk2@suse.de> <20180831070722.wnulbbmillxkw7ke@suse.de> <20180911114927.gikd3uf3otxn2ekq@suse.de> In-Reply-To: <20180911114927.gikd3uf3otxn2ekq@suse.de> From: Linus Torvalds Date: Tue, 11 Sep 2018 08:20:33 -1000 Message-ID: Subject: Re: 32-bit PTI with THP = userspace corruption To: Joerg Roedel Cc: Thomas Gleixner , Meelis Roos , Linux Kernel Mailing List , linux-mm , Andrea Arcangeli Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 11, 2018 at 1:49 AM Joerg Roedel wrote: > > I had a look into the THP and the HugeTLBfs code, and that is not > really easy to fix there. As I can see it now, there are a few options > to fix that, but most of them are ugly: Just do (4): disable PTI with PAE. Then we can try to make people perhaps not use !PAE very much, and warn if you have PAE disabled on a machine that supports it. As you say, there shouldn't be much of a performance impact from PAE. There is a more noticeable performance impact from HIGHMEM, not from HIGHMEM_64G, iirc. Linus