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 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B8937C433EF for ; Mon, 13 Dec 2021 08:20:46 +0000 (UTC) Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-10-qh4HNYESNCOBT-t0t1nOtA-1; Mon, 13 Dec 2021 03:20:42 -0500 X-MC-Unique: qh4HNYESNCOBT-t0t1nOtA-1 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id A635A101F000; Mon, 13 Dec 2021 08:20:37 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E4F37418E; Mon, 13 Dec 2021 08:20:36 +0000 (UTC) Received: from lists01.pubmisc.prod.ext.phx2.redhat.com (lists01.pubmisc.prod.ext.phx2.redhat.com [10.5.19.33]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id 2F1084BB7C; Mon, 13 Dec 2021 08:20:34 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 1BD8KWIs004198 for ; Mon, 13 Dec 2021 03:20:32 -0500 Received: by smtp.corp.redhat.com (Postfix) id 03A36202696C; Mon, 13 Dec 2021 08:20:32 +0000 (UTC) Received: from mimecast-mx02.redhat.com (mimecast09.extmail.prod.ext.rdu2.redhat.com [10.11.55.25]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F3DCD2026D46 for ; Mon, 13 Dec 2021 08:20:29 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-1.mimecast.com [205.139.110.61]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E41FC2B478C2 for ; Mon, 13 Dec 2021 08:20:28 +0000 (UTC) Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-578-NAx8cV4COcWnTgTZBi7Y5Q-1; Mon, 13 Dec 2021 03:20:25 -0500 X-MC-Unique: NAx8cV4COcWnTgTZBi7Y5Q-1 Received: by verein.lst.de (Postfix, from userid 2407) id 076BF68BFE; Mon, 13 Dec 2021 09:20:21 +0100 (CET) Date: Mon, 13 Dec 2021 09:20:20 +0100 From: Christoph Hellwig To: Dan Williams Message-ID: <20211213082020.GA21462@lst.de> References: <20211209063828.18944-1-hch@lst.de> <20211209063828.18944-6-hch@lst.de> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-loop: dm-devel@redhat.com Cc: Linux NVDIMM , linux-s390 , Dave Jiang , Vasily Gorbik , Mike Snitzer , Miklos Szeredi , Vishal Verma , Heiko Carstens , Matthew Wilcox , virtualization@lists.linux-foundation.org, Christian Borntraeger , device-mapper development , Vivek Goyal , Stefan Hajnoczi , linux-fsdevel , Ira Weiny , Christoph Hellwig , Alasdair Kergon Subject: Re: [dm-devel] [PATCH 5/5] dax: always use _copy_mc_to_iter in dax_copy_to_iter X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Sun, Dec 12, 2021 at 06:48:05AM -0800, Dan Williams wrote: > On Fri, Dec 10, 2021 at 6:05 AM Vivek Goyal wrote: > > > > On Thu, Dec 09, 2021 at 07:38:28AM +0100, Christoph Hellwig wrote: > > > While using the MC-safe copy routines is rather pointless on a virtual device > > > like virtiofs, > > > > I was wondering about that. Is it completely pointless. > > > > Typically we are just mapping host page cache into qemu address space. > > That shows as virtiofs device pfn in guest and that pfn is mapped into > > guest application address space in mmap() call. > > > > Given on host its DRAM, so I would not expect machine check on load side > > so there was no need to use machine check safe variant. > > That's a broken assumption, DRAM experiences multi-bit ECC errors. > Machine checks, data aborts, etc existed before PMEM. So the conclusion here is that we should always use the mc safe variant? -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel 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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9F2AAC433F5 for ; Mon, 13 Dec 2021 08:20:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232793AbhLMIUZ (ORCPT ); Mon, 13 Dec 2021 03:20:25 -0500 Received: from verein.lst.de ([213.95.11.211]:46625 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231484AbhLMIUY (ORCPT ); Mon, 13 Dec 2021 03:20:24 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id 076BF68BFE; Mon, 13 Dec 2021 09:20:21 +0100 (CET) Date: Mon, 13 Dec 2021 09:20:20 +0100 From: Christoph Hellwig To: Dan Williams Cc: Vivek Goyal , Christoph Hellwig , Vishal Verma , Dave Jiang , Alasdair Kergon , Mike Snitzer , Ira Weiny , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Stefan Hajnoczi , Miklos Szeredi , Matthew Wilcox , device-mapper development , Linux NVDIMM , linux-s390 , linux-fsdevel , virtualization@lists.linux-foundation.org Subject: Re: [PATCH 5/5] dax: always use _copy_mc_to_iter in dax_copy_to_iter Message-ID: <20211213082020.GA21462@lst.de> References: <20211209063828.18944-1-hch@lst.de> <20211209063828.18944-6-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On Sun, Dec 12, 2021 at 06:48:05AM -0800, Dan Williams wrote: > On Fri, Dec 10, 2021 at 6:05 AM Vivek Goyal wrote: > > > > On Thu, Dec 09, 2021 at 07:38:28AM +0100, Christoph Hellwig wrote: > > > While using the MC-safe copy routines is rather pointless on a virtual device > > > like virtiofs, > > > > I was wondering about that. Is it completely pointless. > > > > Typically we are just mapping host page cache into qemu address space. > > That shows as virtiofs device pfn in guest and that pfn is mapped into > > guest application address space in mmap() call. > > > > Given on host its DRAM, so I would not expect machine check on load side > > so there was no need to use machine check safe variant. > > That's a broken assumption, DRAM experiences multi-bit ECC errors. > Machine checks, data aborts, etc existed before PMEM. So the conclusion here is that we should always use the mc safe variant? 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 Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2156EC433EF for ; Mon, 13 Dec 2021 08:20:32 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id B3D7242547; Mon, 13 Dec 2021 08:20:31 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 0rEpH2jGaqdx; Mon, 13 Dec 2021 08:20:31 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp4.osuosl.org (Postfix) with ESMTPS id 76A0942542; Mon, 13 Dec 2021 08:20:30 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 50BC4C002F; Mon, 13 Dec 2021 08:20:30 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id CA78EC0012 for ; Mon, 13 Dec 2021 08:20:28 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id AA9FF60F0E for ; Mon, 13 Dec 2021 08:20:28 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Qaa6pU26LYGr for ; Mon, 13 Dec 2021 08:20:26 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.8.0 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by smtp3.osuosl.org (Postfix) with ESMTPS id 9A67560EFE for ; Mon, 13 Dec 2021 08:20:26 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 076BF68BFE; Mon, 13 Dec 2021 09:20:21 +0100 (CET) Date: Mon, 13 Dec 2021 09:20:20 +0100 From: Christoph Hellwig To: Dan Williams Subject: Re: [PATCH 5/5] dax: always use _copy_mc_to_iter in dax_copy_to_iter Message-ID: <20211213082020.GA21462@lst.de> References: <20211209063828.18944-1-hch@lst.de> <20211209063828.18944-6-hch@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Cc: Linux NVDIMM , linux-s390 , Dave Jiang , Vasily Gorbik , Mike Snitzer , Miklos Szeredi , Vishal Verma , Heiko Carstens , Matthew Wilcox , virtualization@lists.linux-foundation.org, Christian Borntraeger , device-mapper development , Vivek Goyal , Stefan Hajnoczi , linux-fsdevel , Ira Weiny , Christoph Hellwig , Alasdair Kergon X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" On Sun, Dec 12, 2021 at 06:48:05AM -0800, Dan Williams wrote: > On Fri, Dec 10, 2021 at 6:05 AM Vivek Goyal wrote: > > > > On Thu, Dec 09, 2021 at 07:38:28AM +0100, Christoph Hellwig wrote: > > > While using the MC-safe copy routines is rather pointless on a virtual device > > > like virtiofs, > > > > I was wondering about that. Is it completely pointless. > > > > Typically we are just mapping host page cache into qemu address space. > > That shows as virtiofs device pfn in guest and that pfn is mapped into > > guest application address space in mmap() call. > > > > Given on host its DRAM, so I would not expect machine check on load side > > so there was no need to use machine check safe variant. > > That's a broken assumption, DRAM experiences multi-bit ECC errors. > Machine checks, data aborts, etc existed before PMEM. So the conclusion here is that we should always use the mc safe variant? _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization