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,USER_AGENT_GIT 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 736C8C2D0BE for ; Mon, 9 Dec 2019 22:54:02 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 391DA20721 for ; Mon, 9 Dec 2019 22:54:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="LfvYnGtM" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 391DA20721 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id CCAE36B291B; Mon, 9 Dec 2019 17:53:59 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C72E66B291D; Mon, 9 Dec 2019 17:53:59 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A830C6B291B; Mon, 9 Dec 2019 17:53:59 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0182.hostedemail.com [216.40.44.182]) by kanga.kvack.org (Postfix) with ESMTP id 927356B291B for ; Mon, 9 Dec 2019 17:53:59 -0500 (EST) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id 17842180AD81D for ; Mon, 9 Dec 2019 22:53:59 +0000 (UTC) X-FDA: 76247107398.17.lead53_57261c8c7559 X-HE-Tag: lead53_57261c8c7559 X-Filterd-Recvd-Size: 8702 Received: from hqnvemgate26.nvidia.com (hqnvemgate26.nvidia.com [216.228.121.65]) by imf09.hostedemail.com (Postfix) with ESMTP for ; Mon, 9 Dec 2019 22:53:57 +0000 (UTC) Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Mon, 09 Dec 2019 14:53:49 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Mon, 09 Dec 2019 14:53:54 -0800 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Mon, 09 Dec 2019 14:53:54 -0800 Received: from HQMAIL111.nvidia.com (172.20.187.18) by HQMAIL111.nvidia.com (172.20.187.18) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 9 Dec 2019 22:53:54 +0000 Received: from rnnvemgw01.nvidia.com (10.128.109.123) by HQMAIL111.nvidia.com (172.20.187.18) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Mon, 9 Dec 2019 22:53:53 +0000 Received: from blueforge.nvidia.com (Not Verified[10.110.48.28]) by rnnvemgw01.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Mon, 09 Dec 2019 14:53:53 -0800 From: John Hubbard To: Andrew Morton CC: Al Viro , Alex Williamson , Benjamin Herrenschmidt , =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= , Christoph Hellwig , Dan Williams , Daniel Vetter , Dave Chinner , David Airlie , "David S . Miller" , Ira Weiny , Jan Kara , Jason Gunthorpe , Jens Axboe , Jonathan Corbet , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Magnus Karlsson , Mauro Carvalho Chehab , Michael Ellerman , Michal Hocko , Mike Kravetz , Paul Mackerras , Shuah Khan , Vlastimil Babka , , , , , , , , , , , , , LKML , John Hubbard , Christoph Hellwig Subject: [PATCH v8 04/26] mm: devmap: refactor 1-based refcounting for ZONE_DEVICE pages Date: Mon, 9 Dec 2019 14:53:22 -0800 Message-ID: <20191209225344.99740-5-jhubbard@nvidia.com> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191209225344.99740-1-jhubbard@nvidia.com> References: <20191209225344.99740-1-jhubbard@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=1575932029; bh=r3XA8lSkA5Bnz921S0tMCXc9LaTJg03zUmdbkjLWRbI=; 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=LfvYnGtM+fY384MUNqpbAa8qk7mekXwQmvZD6CCDk4Be0mM/wixeUTJOBgA6s52ex qQzMYlTBpFSmNCzVtfu+t/mAPl+rZQfBne1t+Gh4kdg5ugiYwX/x1vFlQiQvZv7EfO Y2gLD+tlPmU7Aj9HnqAsKp09hiNmbro8fvwMhPguSNEkD/gxjpa+9U8nUL1LptlOQ4 Uj7REaD8Ev3ubLe9XIrCPKImSG3BoXsVaJv8Louwex4QCcFKc0nJFpR1r6Q+cY/iDj o1fx+rkfe6qmvGLt38zpo2V8llX+P8vnqcapLdtRuqNl8ZWthSrdmoGGSqRLI+DVv5 PVjxZZrmaejSA== 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: An upcoming patch changes and complicates the refcounting and especially the "put page" aspects of it. In order to keep everything clean, refactor the devmap page release routines: * Rename put_devmap_managed_page() to page_is_devmap_managed(), and limit the functionality to "read only": return a bool, with no side effects. * Add a new routine, put_devmap_managed_page(), to handle checking what kind of page it is, and what kind of refcount handling it requires. * Rename __put_devmap_managed_page() to free_devmap_managed_page(), and limit the functionality to unconditionally freeing a devmap page. This is originally based on a separate patch by Ira Weiny, which applied to an early version of the put_user_page() experiments. Since then, J=C3=A9r=C3=B4me Glisse suggested the refactoring described abo= ve. Cc: Christoph Hellwig Suggested-by: J=C3=A9r=C3=B4me Glisse Reviewed-by: Dan Williams Reviewed-by: Jan Kara Signed-off-by: Ira Weiny Signed-off-by: John Hubbard --- include/linux/mm.h | 17 +++++++++++++---- mm/memremap.c | 16 ++-------------- mm/swap.c | 24 ++++++++++++++++++++++++ 3 files changed, 39 insertions(+), 18 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index c97ea3b694e6..77a4df06c8a7 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -952,9 +952,10 @@ static inline bool is_zone_device_page(const struct pa= ge *page) #endif =20 #ifdef CONFIG_DEV_PAGEMAP_OPS -void __put_devmap_managed_page(struct page *page); +void free_devmap_managed_page(struct page *page); DECLARE_STATIC_KEY_FALSE(devmap_managed_key); -static inline bool put_devmap_managed_page(struct page *page) + +static inline bool page_is_devmap_managed(struct page *page) { if (!static_branch_unlikely(&devmap_managed_key)) return false; @@ -963,7 +964,6 @@ static inline bool put_devmap_managed_page(struct page = *page) switch (page->pgmap->type) { case MEMORY_DEVICE_PRIVATE: case MEMORY_DEVICE_FS_DAX: - __put_devmap_managed_page(page); return true; default: break; @@ -971,7 +971,14 @@ static inline bool put_devmap_managed_page(struct page= *page) return false; } =20 +bool put_devmap_managed_page(struct page *page); + #else /* CONFIG_DEV_PAGEMAP_OPS */ +static inline bool page_is_devmap_managed(struct page *page) +{ + return false; +} + static inline bool put_devmap_managed_page(struct page *page) { return false; @@ -1028,8 +1035,10 @@ static inline void put_page(struct page *page) * need to inform the device driver through callback. See * include/linux/memremap.h and HMM for details. */ - if (put_devmap_managed_page(page)) + if (page_is_devmap_managed(page)) { + put_devmap_managed_page(page); return; + } =20 if (put_page_testzero(page)) __put_page(page); diff --git a/mm/memremap.c b/mm/memremap.c index e899fa876a62..2ba773859031 100644 --- a/mm/memremap.c +++ b/mm/memremap.c @@ -411,20 +411,8 @@ struct dev_pagemap *get_dev_pagemap(unsigned long pfn, EXPORT_SYMBOL_GPL(get_dev_pagemap); =20 #ifdef CONFIG_DEV_PAGEMAP_OPS -void __put_devmap_managed_page(struct page *page) +void free_devmap_managed_page(struct page *page) { - int count =3D page_ref_dec_return(page); - - /* still busy */ - if (count > 1) - return; - - /* only triggered by the dev_pagemap shutdown path */ - if (count =3D=3D 0) { - __put_page(page); - return; - } - /* notify page idle for dax */ if (!is_device_private_page(page)) { wake_up_var(&page->_refcount); @@ -461,5 +449,5 @@ void __put_devmap_managed_page(struct page *page) page->mapping =3D NULL; page->pgmap->ops->page_free(page); } -EXPORT_SYMBOL(__put_devmap_managed_page); +EXPORT_SYMBOL(free_devmap_managed_page); #endif /* CONFIG_DEV_PAGEMAP_OPS */ diff --git a/mm/swap.c b/mm/swap.c index 5341ae93861f..49f7c2eea0ba 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -1102,3 +1102,27 @@ void __init swap_setup(void) * _really_ don't want to cluster much more */ } + +#ifdef CONFIG_DEV_PAGEMAP_OPS +bool put_devmap_managed_page(struct page *page) +{ + bool is_devmap =3D page_is_devmap_managed(page); + + if (is_devmap) { + int count =3D page_ref_dec_return(page); + + /* + * devmap page refcounts are 1-based, rather than 0-based: if + * refcount is 1, then the page is free and the refcount is + * stable because nobody holds a reference on the page. + */ + if (count =3D=3D 1) + free_devmap_managed_page(page); + else if (!count) + __put_page(page); + } + + return is_devmap; +} +EXPORT_SYMBOL(put_devmap_managed_page); +#endif --=20 2.24.0