From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yw0-f199.google.com (mail-yw0-f199.google.com [209.85.161.199]) by kanga.kvack.org (Postfix) with ESMTP id EAE066B0038 for ; Tue, 6 Sep 2016 13:32:17 -0400 (EDT) Received: by mail-yw0-f199.google.com with SMTP id u82so211876063ywc.0 for ; Tue, 06 Sep 2016 10:32:17 -0700 (PDT) Received: from mail-oi0-x22e.google.com (mail-oi0-x22e.google.com. [2607:f8b0:4003:c06::22e]) by mx.google.com with ESMTPS id k141si31297562itb.16.2016.09.06.10.32.17 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 06 Sep 2016 10:32:17 -0700 (PDT) Received: by mail-oi0-x22e.google.com with SMTP id y2so83853856oie.0 for ; Tue, 06 Sep 2016 10:32:17 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <147318056046.30325.5100892122988191500.stgit@dwillia2-desk3.amr.corp.intel.com> <147318058165.30325.16762406881120129093.stgit@dwillia2-desk3.amr.corp.intel.com> From: Dan Williams Date: Tue, 6 Sep 2016 10:32:16 -0700 Message-ID: Subject: Re: [PATCH 4/5] mm: fix cache mode of dax pmd mappings Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Matthew Wilcox Cc: "linux-nvdimm@lists.01.org" , Toshi Kani , Nilesh Choudhury , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" , "linux-mm@kvack.org" , "akpm@linux-foundation.org" , Ross Zwisler , "Kirill A. Shutemov" , Kai Zhang On Tue, Sep 6, 2016 at 10:20 AM, Matthew Wilcox wr= ote: > I have no objection to this patch going in for now. > > Longer term, surely we want to track what mode the PFNs are mapped in? T= here are various bizarre suppositions out there about how persistent memory= should be mapped, and it's probably better if the kernel ignores what the = user specifies and keeps everything sane. I've read the dire warnings in t= he Intel architecture manual and I have no desire to deal with the inevitab= le bug reports on some hardware I don't own and requires twenty weeks of op= eration in order to observe the bug. Is there a way for userspace to establish mappings with different cache modes, besides via /dev/mem? That was the motivation for CONFIG_IO_STRICT_DEVMEM. -- 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