From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: allowed pages in the block later, was Re: [Ext2-devel] [PATCH] ext3: avoid sending down non-refcounted pages Date: Sat, 10 Dec 2005 16:47:36 -0800 Message-ID: <20051210164736.6e4eaa3f.akpm@osdl.org> References: <20051208180900T.fujita.tomonori@lab.ntt.co.jp> <20051208101833.GM14509@schatzie.adilger.int> <20051208134239.GA13376@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: fujita.tomonori@lab.ntt.co.jp, michaelc@cs.wisc.edu, hch@infradead.org, linux-fsdevel@vger.kernel.org, ext2-devel@lists.sourceforge.net, open-iscsi@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Return-path: Received: from smtp.osdl.org ([65.172.181.4]:56784 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1161077AbVLKAsQ (ORCPT ); Sat, 10 Dec 2005 19:48:16 -0500 To: Christoph Hellwig In-Reply-To: <20051208134239.GA13376@infradead.org> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Christoph Hellwig wrote: > > The problem we're trying to solve here is how do implement network block > devices (nbd, iscsi) efficiently. The zero copy codepath in the networking > layer does need to grab additional references to pages. So to use sendpage > we need a refcountable page. pages used by the slab allocator are not > normally refcounted so try to do get_page/pub_page on them will break. I don't get it. Doing get_page/put_page on a slab-allocated page should do the right thing?