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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id g18si85394pgg.522.2019.02.07.13.34.03 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 07 Feb 2019 13:34:03 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) client-ip=2607:7c80:54:e::133; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=fYYyMijD; spf=pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=willy@infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=HG08h4CmN+ciP15Ueo5cb7ygRxxsUAXIB93CDy90Co8=; b=fYYyMijD4PfDANyUpdYdCZ8Fs xs3HOHrHkVF/mvPORPIGrhDkfF9kKyKSNB6iSti79NsolaETOQ5NAl3oHwWcC1kUcfprUH+MlSWtM PX5hfDmGNCnVh71sLL0glMteCIYyOTAk5m0EFuGtXXdUkQTYuX9M6M9bzrnMtxUvzTvjgiX1GWjvN 3+Ux8j7ezVnOquhfvEtd1uqiF2R+JD10+geAUz1rKQEbGnzG3XNdF0O8CMQhzkgy6jKeTHAU+dTTd ag65a59UVQbkgVjBjeGISZkHJ7MnLZfeaCa+5HIhUUuMk/sgQ+EluRVF5b+mRawqZ/pmMIqaShjGP 8biSq85hg==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1grrJ2-0001RM-NI; Thu, 07 Feb 2019 21:34:00 +0000 Date: Thu, 7 Feb 2019 13:34:00 -0800 From: Matthew Wilcox To: David Miller Cc: ilias.apalodimas@linaro.org, brouer@redhat.com, tariqt@mellanox.com, toke@redhat.com, netdev@vger.kernel.org, mgorman@techsingularity.net, linux-mm@kvack.org Subject: Re: [RFC, PATCH] net: page_pool: Don't use page->private to store dma_addr_t Message-ID: <20190207213400.GA21860@bombadil.infradead.org> References: <1549550196-25581-1-git-send-email-ilias.apalodimas@linaro.org> <20190207150745.GW21860@bombadil.infradead.org> <20190207152034.GA3295@apalos> <20190207.132519.1698007650891404763.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190207.132519.1698007650891404763.davem@davemloft.net> User-Agent: Mutt/1.9.2 (2017-12-15) 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 Thu, Feb 07, 2019 at 01:25:19PM -0800, David Miller wrote: > From: Ilias Apalodimas > Date: Thu, 7 Feb 2019 17:20:34 +0200 > > > Well updating struct page is the final goal, hence the comment. I am mostly > > looking for opinions here since we are trying to store dma addresses which are > > irrelevant to pages. Having dma_addr_t definitions in mm-related headers is a > > bit controversial isn't it ? If we can add that, then yes the code would look > > better > > I fundamentally disagree. > > One of the core operations performed on a page is mapping it so that a device > and use it. > > Why have ancillary data structure support for this all over the place, rather > than in the common spot which is the page. > > A page really is not just a 'mm' structure, it is a system structure. +1 The fundamental point of computing is to do I/O.