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[216.228.121.143]) by mx.google.com with ESMTPS id r129si12860790ywg.165.2019.07.19.12.30.08 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 19 Jul 2019 12:30:08 -0700 (PDT) Received-SPF: pass (google.com: domain of rcampbell@nvidia.com designates 216.228.121.143 as permitted sender) client-ip=216.228.121.143; Authentication-Results: mx.google.com; dkim=pass header.i=@nvidia.com header.s=n1 header.b=PQexChhB; spf=pass (google.com: domain of rcampbell@nvidia.com designates 216.228.121.143 as permitted sender) smtp.mailfrom=rcampbell@nvidia.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=nvidia.com Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqemgate14.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Fri, 19 Jul 2019 12:30:08 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Fri, 19 Jul 2019 12:30:07 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Fri, 19 Jul 2019 12:30:07 -0700 Received: from HQMAIL105.nvidia.com (172.20.187.12) by HQMAIL104.nvidia.com (172.18.146.11) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Fri, 19 Jul 2019 19:30:03 +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; Fri, 19 Jul 2019 19:30:03 +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 ; Fri, 19 Jul 2019 12:30:03 -0700 From: Ralph Campbell To: CC: , Ralph Campbell , John Hubbard , Matthew Wilcox , Vlastimil Babka , Christoph Lameter , "Dave Hansen" , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , "Kirill A . Shutemov" , Lai Jiangshan , Martin Schwidefsky , Pekka Enberg , Randy Dunlap , Andrey Ryabinin , Christoph Hellwig , Jason Gunthorpe , Andrew Morton , Linus Torvalds Subject: [PATCH v2 1/3] mm: document zone device struct page field usage Date: Fri, 19 Jul 2019 12:29:53 -0700 Message-ID: <20190719192955.30462-2-rcampbell@nvidia.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190719192955.30462-1-rcampbell@nvidia.com> References: <20190719192955.30462-1-rcampbell@nvidia.com> MIME-Version: 1.0 X-NVConfidentiality: public DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1563564608; bh=5BzlDT+tWQDH/Xg8OWZLql9VCG1Bt/EFc4+GdPSo8lc=; 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=PQexChhBZx3+OWZZ6A+wrhywrKQby9FhOWY5qduhs3ASzwzTGT5/e+pR4+/0KGzdu zc8xUGQTFKV/eGaRb3lqi32sg+IiQX2anYnS2PocFFF5W2OhNynMmfZuXm9iI+f0JL WB2FhbKiTQMV/TXeGZcU0LIVz4FwdypJ88fXi61dgUV+Oss+CYgNHRCpRN7u0Vs0op 50S4AqXNU97o0O36Y4EHqNSij20fLwUfZQ8hH3LzoXyI0+w1dg8aQGg13GvjJQSXXp aTksokvD/6cJAU4uRYdMCJe3hyLMENdviYEtmb9w+0e7IrM0fgMbp/3zzRZFk7HtLW 8KBOIAdX0ZUpQ== 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: X-Virus-Scanned: ClamAV using ClamSMTP 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. Restructure struct page and add comments 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: Jérôme 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 Reviewed-by: Christoph Hellwig --- include/linux/mm_types.h | 42 +++++++++++++++++++++++++++------------- 1 file changed, 29 insertions(+), 13 deletions(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 3a37a89eb7a7..f6c52e44d40c 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -76,13 +76,35 @@ struct page { * avoid collision and false-positive PageTail(). */ union { - struct { /* Page cache and anonymous pages */ - /** - * @lru: Pageout list, eg. active_list protected by - * pgdat->lru_lock. Sometimes used as a generic list - * by the page owner. - */ - struct list_head lru; + struct { /* Page cache, anonymous, ZONE_DEVICE pages */ + union { + /** + * @lru: Pageout list, e.g., active_list + * protected by pgdat->lru_lock. Sometimes + * used as a generic list by the page owner. + */ + struct list_head lru; + /** + * ZONE_DEVICE pages are never on the lru + * list so they reuse the list space. + * ZONE_DEVICE private pages are counted as + * being mapped so the @mapping and @index + * fields are used while the page is migrated + * to device private memory. + * ZONE_DEVICE MEMORY_DEVICE_FS_DAX pages also + * use the @mapping and @index fields when pmem + * backed DAX files are mapped. + */ + struct { + /** + * @pgmap: Points to the hosting + * device page map. + */ + struct dev_pagemap *pgmap; + /** @zone_device_data: opaque data. */ + void *zone_device_data; + }; + }; /* See page-flags.h for PAGE_MAPPING_FLAGS */ struct address_space *mapping; pgoff_t index; /* Our offset within mapping. */ @@ -155,12 +177,6 @@ struct page { spinlock_t ptl; #endif }; - struct { /* ZONE_DEVICE pages */ - /** @pgmap: Points to the hosting device page map. */ - struct dev_pagemap *pgmap; - void *zone_device_data; - unsigned long _zd_pad_1; /* uses mapping */ - }; /** @rcu_head: You can use this to free a page by RCU. */ struct rcu_head rcu_head;