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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 1C822C433DB for ; Tue, 19 Jan 2021 18:35:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9C11323103 for ; Tue, 19 Jan 2021 18:35:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9C11323103 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=soleen.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id F391F6B005D; Tue, 19 Jan 2021 13:35:07 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EEA8F6B006C; Tue, 19 Jan 2021 13:35:07 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E270F6B006E; Tue, 19 Jan 2021 13:35:07 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0136.hostedemail.com [216.40.44.136]) by kanga.kvack.org (Postfix) with ESMTP id CCDCA6B005D for ; Tue, 19 Jan 2021 13:35:07 -0500 (EST) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 9BDDD8249980 for ; Tue, 19 Jan 2021 18:35:06 +0000 (UTC) X-FDA: 77723376612.02.road38_480fad727554 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin02.hostedemail.com (Postfix) with ESMTP id 4E16E10097AA0 for ; Tue, 19 Jan 2021 18:35:06 +0000 (UTC) X-HE-Tag: road38_480fad727554 X-Filterd-Recvd-Size: 4220 Received: from mail-ej1-f53.google.com (mail-ej1-f53.google.com [209.85.218.53]) by imf28.hostedemail.com (Postfix) with ESMTP for ; Tue, 19 Jan 2021 18:35:03 +0000 (UTC) Received: by mail-ej1-f53.google.com with SMTP id hs11so27615083ejc.1 for ; Tue, 19 Jan 2021 10:35:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=soleen.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Ct+vcUpxOjScIL+qAWZyF8knx6gxVliNtyQsEHsrnBQ=; b=BZe8awveFMq5GincJDNVuax+pU2IN/5C9pNKCNqUs9yROKpwZH1EZi26i4cskhGgts LII0hwEUCFrmUnS9VhpzvWJaH/THjYoCLkOL5y59cRy9Pi8y8m7cle0ouKhiR+qVd48Y 1oSq4GGmA983vt0d8xpUHcVPHW/ai9FuZwTL9vqIiU/gHm3IA5IuUXBOm5GA/XKdEobF rwKxMX2jZR+kjWjBjA/ZQh/tFExxv01CpNHBLazxFhAIQGrcXcvtxWNt0O385H6icruS pNEIfHrArsdVfXtKXjZp7ImGEY3/7TOtRniIqG5iFaGU2sjo1pdfb/EbSos1zRgaftyp PqTw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Ct+vcUpxOjScIL+qAWZyF8knx6gxVliNtyQsEHsrnBQ=; b=HUAY7KTOq7n+Qk+gA7xhQoHmSTTs7n0wBkb+za7mCmFAs46MFh2vUPBoOV+eKeujAC e+LW1x83ehe4mLuQX/B/N3lf8M+CmxL9cnG38muyayMcAcHjYxIYvT6tTYq0iD3G590G JiwjB3DLeQRVtMk+NOW2avHdhqKu+p5w5yn2cxbYigreAHj1+3/xQ24daq8Al18xNwe5 aZ0yeVIBoSCOqR9/IlBeguBSEZY2Mzd+AHdC04DeEoldZtAd8aGPrHGio++DWz2cCM/q MnJ/Vp7CRmItVFYU6igI4u8zg3fRCqHfnVxzsX/BcN+amVG1fLzONdYDKA1H1OJV/+FD e0DA== X-Gm-Message-State: AOAM531+BR6/8w0/UxgD7d5qtJXY8x/gztFpVMAKHaR/A6e0WZJdTdSB K7uopLPlOpjEJqXxzUK7KGlXNc2iE8VFEQ2f4VT5hw== X-Google-Smtp-Source: ABdhPJxq2+sfTG3ORVXYvyp4uAxt4hNSEd/oukNuDPHO3IHBTF8PXk9SD4PxTgPj0Ma3BgJmPR49bmjsQLfU4aQP2Oc= X-Received: by 2002:a17:906:cedd:: with SMTP id si29mr4046472ejb.426.1611081302258; Tue, 19 Jan 2021 10:35:02 -0800 (PST) MIME-Version: 1.0 References: <20210119043920.155044-1-pasha.tatashin@soleen.com> <20210119043920.155044-9-pasha.tatashin@soleen.com> <20210119183013.GB4605@ziepe.ca> In-Reply-To: <20210119183013.GB4605@ziepe.ca> From: Pavel Tatashin Date: Tue, 19 Jan 2021 13:34:26 -0500 Message-ID: Subject: Re: [PATCH v5 08/14] mm/gup: do not allow zero page for pinned pages To: Jason Gunthorpe Cc: LKML , linux-mm , Andrew Morton , Vlastimil Babka , Michal Hocko , David Hildenbrand , Oscar Salvador , Dan Williams , Sasha Levin , Tyler Hicks , Joonsoo Kim , mike.kravetz@oracle.com, Steven Rostedt , Ingo Molnar , Peter Zijlstra , Mel Gorman , Matthew Wilcox , David Rientjes , John Hubbard , Linux Doc Mailing List , Ira Weiny , linux-kselftest@vger.kernel.org Content-Type: text/plain; charset="UTF-8" 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: On Tue, Jan 19, 2021 at 1:30 PM Jason Gunthorpe wrote: > > On Mon, Jan 18, 2021 at 11:39:14PM -0500, Pavel Tatashin wrote: > > Zero page should not be used for long term pinned pages. Once pages > > are pinned their physical addresses cannot changed until they are unpinned. > > > > Guarantee to always return real pages when they are pinned by adding > > FOLL_WRITE. > > > > Signed-off-by: Pavel Tatashin > > --- > > mm/gup.c | 10 +++++++++- > > 1 file changed, 9 insertions(+), 1 deletion(-) > > No, this will definitely break things What will break > > Why does the zero page have to be movable? It is not even about being movable, we can't cow pinned pages returned by GUP call, how can we use zero page for that? > > Jason