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=-9.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 AFCDCC76186 for ; Wed, 24 Jul 2019 23:27:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8409A2189F for ; Wed, 24 Jul 2019 23:27:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="kuNrmdut" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387881AbfGXX1P (ORCPT ); Wed, 24 Jul 2019 19:27:15 -0400 Received: from hqemgate14.nvidia.com ([216.228.121.143]:15286 "EHLO hqemgate14.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729824AbfGXX1O (ORCPT ); Wed, 24 Jul 2019 19:27:14 -0400 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqemgate14.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Wed, 24 Jul 2019 16:27:14 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Wed, 24 Jul 2019 16:27:13 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Wed, 24 Jul 2019 16:27:13 -0700 Received: from HQMAIL105.nvidia.com (172.20.187.12) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Wed, 24 Jul 2019 23:27:08 +0000 Received: from hqnvemgw01.nvidia.com (172.20.150.20) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Wed, 24 Jul 2019 23:27:08 +0000 Received: from rcampbell-dev.nvidia.com (Not Verified[10.110.48.66]) by hqnvemgw01.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Wed, 24 Jul 2019 16:27:07 -0700 From: Ralph Campbell To: CC: , Ralph Campbell , John Hubbard , Matthew Wilcox , Vlastimil Babka , Christoph Lameter , "Dave Hansen" , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , "Kirill A . Shutemov" , Lai Jiangshan , Martin Schwidefsky , Pekka Enberg , Randy Dunlap , Andrey Ryabinin , Christoph Hellwig , Jason Gunthorpe , Andrew Morton , Linus Torvalds Subject: [PATCH v3 1/3] mm: document zone device struct page field usage Date: Wed, 24 Jul 2019 16:26:58 -0700 Message-ID: <20190724232700.23327-2-rcampbell@nvidia.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190724232700.23327-1-rcampbell@nvidia.com> References: <20190724232700.23327-1-rcampbell@nvidia.com> MIME-Version: 1.0 X-NVConfidentiality: public Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1564010834; bh=R7tBXQO9rPgjXDqjGz3N+EME0mRb0btVdpzxMZ8l/ZM=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:X-NVConfidentiality: Content-Type:Content-Transfer-Encoding; b=kuNrmdutQu8OtJz0LkyZEgZtbgpSB31azxVA6IxHVhWwyekrrPMk35utH++IUUR0V ySZRHjTnQuRxkH0mSRZr0lRX8zjcwQo3cSTXfApyuOpwqFkqCoCiNAHnUNbMP3YhOs fvYiGYGvu8V9As7306izV/f8A7DsPZU0zIOSCCJa6mCtyaXg6gIRyFnjjzs13WYPWA +RuZoYfW0QBPbXhlmlgRYiiMtwtonS/EbKE7Gq9TxQbZtH0EPUSzQ1XJO4Adpk0SXl Wr32U6NJLVw+CC1G77WQ4pgNY01eGesQd/e/J1j5Yk22sCMPNUCHDfJLKSuGCaJAHh /9ROeBw+Xc+CA== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Struct page for ZONE_DEVICE private pages uses the page->mapping and and page->index fields while the source anonymous pages are migrated to device private memory. This is so rmap_walk() can find the page when migrating the ZONE_DEVICE private page back to system memory. ZONE_DEVICE pmem backed fsdax pages also use the page->mapping and page->index fields when files are mapped into a process address space. Add comments to struct page and remove the unused "_zd_pad_1" field to make this more clear. Signed-off-by: Ralph Campbell Reviewed-by: John Hubbard Cc: Matthew Wilcox Cc: Vlastimil Babka Cc: Christoph Lameter Cc: Dave Hansen Cc: J=C3=A9r=C3=B4me Glisse Cc: "Kirill A . Shutemov" Cc: Lai Jiangshan Cc: Martin Schwidefsky Cc: Pekka Enberg Cc: Randy Dunlap Cc: Andrey Ryabinin Cc: Christoph Hellwig Cc: Jason Gunthorpe Cc: Andrew Morton Cc: Linus Torvalds --- include/linux/mm_types.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 3a37a89eb7a7..6a7a1083b6fb 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -159,7 +159,16 @@ struct page { /** @pgmap: Points to the hosting device page map. */ struct dev_pagemap *pgmap; void *zone_device_data; - unsigned long _zd_pad_1; /* uses mapping */ + /* + * ZONE_DEVICE private pages are counted as being + * mapped so the next 3 words hold the mapping, index, + * and private fields from the source anonymous or + * page cache page while the page is migrated to device + * private memory. + * ZONE_DEVICE MEMORY_DEVICE_FS_DAX pages also + * use the mapping, index, and private fields when + * pmem backed DAX files are mapped. + */ }; =20 /** @rcu_head: You can use this to free a page by RCU. */ --=20 2.20.1