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[213.95.11.211]) by mx.google.com with ESMTPS id l18si14741634wrx.371.2019.07.16.21.38.25 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 16 Jul 2019 21:38:25 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of hch@lst.de designates 213.95.11.211 as permitted sender) client-ip=213.95.11.211; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of hch@lst.de designates 213.95.11.211 as permitted sender) smtp.mailfrom=hch@lst.de Received: by verein.lst.de (Postfix, from userid 2407) id 416C168B05; Wed, 17 Jul 2019 06:38:24 +0200 (CEST) Date: Wed, 17 Jul 2019 06:38:24 +0200 From: Christoph Hellwig To: John Hubbard Cc: Christoph Hellwig , Ralph Campbell , linux-mm@kvack.org, linux-kernel@vger.kernel.org, willy@infradead.org, Vlastimil Babka , Christoph Lameter , Dave Hansen , =?iso-8859-1?B?Suly9G1l?= Glisse , "Kirill A . Shutemov" , Lai Jiangshan , Martin Schwidefsky , Pekka Enberg , Randy Dunlap , Andrey Ryabinin , Jason Gunthorpe , Andrew Morton , Linus Torvalds Subject: Re: [PATCH 1/3] mm: document zone device struct page reserved fields Message-ID: <20190717043824.GA4755@lst.de> References: <20190717001446.12351-1-rcampbell@nvidia.com> <20190717001446.12351-2-rcampbell@nvidia.com> <26a47482-c736-22c4-c21b-eb5f82186363@nvidia.com> <20190717042233.GA4529@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) 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, Jul 16, 2019 at 09:31:33PM -0700, John Hubbard wrote: > OK, so just delete all the _zd_pad_* fields? Works for me. It's misleading to > calling something padding, if it's actually unavailable because it's used > in the other union, so deleting would be even better than commenting. > > In that case, it would still be nice to have this new snippet, right?: I hope willy can chime in a bit on his thoughts about how the union in struct page should look like. The padding at the end of the sub-structs certainly looks pointless, and other places don't use it either. But if we are using the other fields it almost seems to me like we only want to union the lru field in the first sub-struct instead of overlaying most of it.