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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 51956C3404B for ; Tue, 18 Feb 2020 21:09:42 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 11D0F2176D for ; Tue, 18 Feb 2020 21:09:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Yr/QXOu9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 11D0F2176D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A2EF86B0005; Tue, 18 Feb 2020 16:09:41 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9B7F56B0006; Tue, 18 Feb 2020 16:09:41 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 87FB76B0007; Tue, 18 Feb 2020 16:09:41 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0032.hostedemail.com [216.40.44.32]) by kanga.kvack.org (Postfix) with ESMTP id 6CC326B0005 for ; Tue, 18 Feb 2020 16:09:41 -0500 (EST) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 2C316181AEF00 for ; Tue, 18 Feb 2020 21:09:41 +0000 (UTC) X-FDA: 76504489362.01.power69_1a4fa05879502 X-HE-Tag: power69_1a4fa05879502 X-Filterd-Recvd-Size: 3631 Received: from us-smtp-delivery-1.mimecast.com (us-smtp-2.mimecast.com [205.139.110.61]) by imf30.hostedemail.com (Postfix) with ESMTP for ; Tue, 18 Feb 2020 21:09:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1582060180; 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=E9mRKEIAjKB1Xq/wMpY1paNLH79mcLaPS2RPUKkvMDQ=; b=Yr/QXOu9ujkHAySGltskvI+94bFznfdJkkNbjUXSK9vXe9hUSww5y8LDRvC65hWQz/YnVh AtHkzBavWt87DWTqStIZadINzBts2NMrMLf8Lw842Xb6f8n4V56s1WbRx9jpg7Mn07l1vo +ExiLwU5U/qIEFn2xDlRQQ+wXJWkKAM= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-218-D5lFg6opNpGvWSZgTdsX6A-1; Tue, 18 Feb 2020 16:09:34 -0500 X-MC-Unique: D5lFg6opNpGvWSZgTdsX6A-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9EA32DBA3; Tue, 18 Feb 2020 21:09:32 +0000 (UTC) Received: from segfault.boston.devel.redhat.com (segfault.boston.devel.redhat.com [10.19.60.26]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A890060BE1; Tue, 18 Feb 2020 21:09:31 +0000 (UTC) From: Jeff Moyer To: Dan Williams Cc: Murphy Zhou , linux-nvdimm , Jia He , Linux MM , "Shutemov\, Kirill" , Linux Kernel Mailing List Subject: Re: [PATCH] mm: get rid of WARN if failed to cow user pages References: <20191225054227.gii6ctjkuddjnprs@xzhoux.usersys.redhat.com> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 Date: Tue, 18 Feb 2020 16:09:30 -0500 In-Reply-To: (Dan Williams's message of "Tue, 14 Jan 2020 22:02:34 -0800") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Dan Williams writes: > [ drop Ross, add Kirill, linux-mm, and lkml ] > > On Tue, Dec 24, 2019 at 9:42 PM Murphy Zhou wrote: >> >> By running xfstests with fsdax enabled, generic/437 always hits this >> warning[1] since this commit: >> >> commit 83d116c53058d505ddef051e90ab27f57015b025 >> Author: Jia He >> Date: Fri Oct 11 22:09:39 2019 +0800 >> >> mm: fix double page fault on arm64 if PTE_AF is cleared >> >> Looking at the test program[2] generic/437 uses, it's pretty easy >> to hit this warning. Remove this WARN as it seems not necessary. > > This is not sufficient justification. Does this same test fail without > DAX? If not, why not? At a minimum you need to explain why this is not > indicating a problem. I ran into this, too, and Kirill has posted a patch[1] to fix the issue. Note that it's a potential data corrupter, so just removing the warning is NOT the right approach. :) -Jeff [1] https://lore.kernel.org/linux-mm/20200218154151.13349-1-kirill.shutemov@linux.intel.com/T/#u