From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Hubbard Subject: [PATCH v6 05/24] mm: devmap: refactor 1-based refcounting for ZONE_DEVICE pages Date: Tue, 19 Nov 2019 00:16:24 -0800 Message-ID: <20191119081643.1866232-6-jhubbard@nvidia.com> References: <20191119081643.1866232-1-jhubbard@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20191119081643.1866232-1-jhubbard@nvidia.com> Sender: linux-kernel-owner@vger.kernel.org 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 M List-Id: dri-devel@lists.freedesktop.org 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 | 27 ++++++++++++++++++++++++--- mm/memremap.c | 16 ++-------------- 2 files changed, 26 insertions(+), 17 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index a2adf95b3f9c..96228376139c 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -967,9 +967,10 @@ 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; @@ -978,7 +979,6 @@ 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; @@ -986,6 +986,27 @@ static inline bool put_devmap_managed_page(struct page= *page) return false; } =20 +static inline 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; +} + #else /* CONFIG_DEV_PAGEMAP_OPS */ static inline bool put_devmap_managed_page(struct 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 */ --=20 2.24.0 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=-9.8 required=3.0 tests=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 A20CDC33CA1 for ; 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Tue, 19 Nov 2019 00:16:56 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Tue, 19 Nov 2019 00:16:53 -0800 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Tue, 19 Nov 2019 00:16:53 -0800 Received: from HQMAIL101.nvidia.com (172.20.187.10) by HQMAIL111.nvidia.com (172.20.187.18) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 19 Nov 2019 08:16:53 +0000 Received: from rnnvemgw01.nvidia.com (10.128.109.123) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Tue, 19 Nov 2019 08:16:51 +0000 Received: from blueforge.nvidia.com (Not Verified[10.110.48.28]) by rnnvemgw01.nvidia.com with Trustwave SEG (v7, 5, 8, 10121) id ; Tue, 19 Nov 2019 00:16:51 -0800 From: John Hubbard To: Andrew Morton Subject: [PATCH v6 05/24] mm: devmap: refactor 1-based refcounting for ZONE_DEVICE pages Date: Tue, 19 Nov 2019 00:16:24 -0800 Message-ID: <20191119081643.1866232-6-jhubbard@nvidia.com> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191119081643.1866232-1-jhubbard@nvidia.com> References: <20191119081643.1866232-1-jhubbard@nvidia.com> MIME-Version: 1.0 X-NVConfidentiality: public X-Mailman-Original-DKIM-Signature: v=1; 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Miller" , Mike Kravetz Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Message-ID: <20191119081624.GvKmRCtn2i9-A6PjcEB-XpYGeDSH-iNWu359dN4sZGs@z> QW4gdXBjb21pbmcgcGF0Y2ggY2hhbmdlcyBhbmQgY29tcGxpY2F0ZXMgdGhlIHJlZmNvdW50aW5n IGFuZAplc3BlY2lhbGx5IHRoZSAicHV0IHBhZ2UiIGFzcGVjdHMgb2YgaXQuIEluIG9yZGVyIHRv IGtlZXAKZXZlcnl0aGluZyBjbGVhbiwgcmVmYWN0b3IgdGhlIGRldm1hcCBwYWdlIHJlbGVhc2Ug cm91dGluZXM6CgoqIFJlbmFtZSBwdXRfZGV2bWFwX21hbmFnZWRfcGFnZSgpIHRvIHBhZ2VfaXNf ZGV2bWFwX21hbmFnZWQoKSwKICBhbmQgbGltaXQgdGhlIGZ1bmN0aW9uYWxpdHkgdG8gInJlYWQg b25seSI6IHJldHVybiBhIGJvb2wsCiAgd2l0aCBubyBzaWRlIGVmZmVjdHMuCgoqIEFkZCBhIG5l dyByb3V0aW5lLCBwdXRfZGV2bWFwX21hbmFnZWRfcGFnZSgpLCB0byBoYW5kbGUgY2hlY2tpbmcK ICB3aGF0IGtpbmQgb2YgcGFnZSBpdCBpcywgYW5kIHdoYXQga2luZCBvZiByZWZjb3VudCBoYW5k bGluZyBpdAogIHJlcXVpcmVzLgoKKiBSZW5hbWUgX19wdXRfZGV2bWFwX21hbmFnZWRfcGFnZSgp 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