From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-x231.google.com (mail-it0-x231.google.com [IPv6:2607:f8b0:4001:c0b::231]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id D799F2007E7E6 for ; Tue, 1 May 2018 14:05:59 -0700 (PDT) Received: by mail-it0-x231.google.com with SMTP id 144-v6so15059422iti.5 for ; Tue, 01 May 2018 14:05:59 -0700 (PDT) MIME-Version: 1.0 References: <152520750404.36522.15462513519590065300.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: <152520750404.36522.15462513519590065300.stgit@dwillia2-desk3.amr.corp.intel.com> From: Linus Torvalds Date: Tue, 01 May 2018 21:05:48 +0000 Message-ID: Subject: Re: [PATCH 0/6] use memcpy_mcsafe() for copy_to_iter() List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Dan Williams Cc: Tony Luck , "linux-nvdimm@lists.01.org" , Peter Zijlstra , the arch/x86 maintainers , Linux Kernel Mailing List , Andy Lutomirski , Ingo Molnar , Borislav Petkov , Al Viro , Thomas Gleixner , Andrew Morton List-ID: On Tue, May 1, 2018 at 1:55 PM Dan Williams wrote: > The result of the bypass is that the kernel treats machine checks during > read as system fatal (reboot) when they could simply be flagged as an > I/O error, similar to performing reads through the pmem driver. Prevent > this fatal condition by deploying memcpy_mcsafe() in the fsdax read > path. How about just changing the rules, and go the old "Don't do that then" way? IOW, get rid of the whole idea that MCS errors should be fatal. It's wrong and pointless anyway. The while approach seems fundamentally buggered, if you ever want to mmap one of these things. And don't you want that? So why continue down a fundamentally broken path? Linus _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751241AbeEAVGA (ORCPT ); Tue, 1 May 2018 17:06:00 -0400 Received: from mail-it0-f49.google.com ([209.85.214.49]:50912 "EHLO mail-it0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750803AbeEAVF7 (ORCPT ); Tue, 1 May 2018 17:05:59 -0400 X-Google-Smtp-Source: AB8JxZoR5crxY7yzwAtc7i/S6K28f1c4XFvGV+HcFPjUY1VgrekQosJV//4+OBF4H3LqOBaV16BFHjN172Q5P5HdUmI= MIME-Version: 1.0 References: <152520750404.36522.15462513519590065300.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: <152520750404.36522.15462513519590065300.stgit@dwillia2-desk3.amr.corp.intel.com> From: Linus Torvalds Date: Tue, 01 May 2018 21:05:48 +0000 Message-ID: Subject: Re: [PATCH 0/6] use memcpy_mcsafe() for copy_to_iter() To: Dan Williams Cc: "linux-nvdimm@lists.01.org" , Tony Luck , Peter Zijlstra , Borislav Petkov , "the arch/x86 maintainers" , Thomas Gleixner , Andy Lutomirski , Ingo Molnar , Al Viro , Andrew Morton , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 1, 2018 at 1:55 PM Dan Williams wrote: > The result of the bypass is that the kernel treats machine checks during > read as system fatal (reboot) when they could simply be flagged as an > I/O error, similar to performing reads through the pmem driver. Prevent > this fatal condition by deploying memcpy_mcsafe() in the fsdax read > path. How about just changing the rules, and go the old "Don't do that then" way? IOW, get rid of the whole idea that MCS errors should be fatal. It's wrong and pointless anyway. The while approach seems fundamentally buggered, if you ever want to mmap one of these things. And don't you want that? So why continue down a fundamentally broken path? Linus