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 18059C433F5 for ; Tue, 14 Dec 2021 13:59:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234611AbhLNN7H (ORCPT ); Tue, 14 Dec 2021 08:59:07 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:44960 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232428AbhLNN7G (ORCPT ); Tue, 14 Dec 2021 08:59:06 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1639490345; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=m/5pRcl9h3yj8MAkqvRPCHvPcL0c1vkmrKvq7UUnKBk=; b=UzRdxE/mQTqhVgFF+18bIUa2Tn92UKJxfy17YFX3FmarrZuOVDsoyISMWw4MFQpBWRe4EI +LrPqx9CtcLCnsu8CxCKZcTnRW3oviixIMI+HvwRlyPS7C7JtBSU4sfTwNVILPe/IqXSqm 4L11ggliQUMqUeeFcI4ym2sO6+YPmNc= 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-93-0kDh8FCsOqi2t6NYQJXz-g-1; Tue, 14 Dec 2021 08:59:04 -0500 X-MC-Unique: 0kDh8FCsOqi2t6NYQJXz-g-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id BA20F1966320; Tue, 14 Dec 2021 13:59:01 +0000 (UTC) Received: from horse.redhat.com (unknown [10.22.33.95]) by smtp.corp.redhat.com (Postfix) with ESMTP id 25B375BE02; Tue, 14 Dec 2021 13:59:01 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id A5F242233DF; Tue, 14 Dec 2021 08:59:00 -0500 (EST) Date: Tue, 14 Dec 2021 08:59:00 -0500 From: Vivek Goyal To: Dan Williams Cc: 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: 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: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 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 we should use MC safe variant when loading from DRAM as well? (If needed platoform support is there). Vivek