From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932347AbVHHXKN (ORCPT ); Mon, 8 Aug 2005 19:10:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932348AbVHHXKM (ORCPT ); Mon, 8 Aug 2005 19:10:12 -0400 Received: from smtp.osdl.org ([65.172.181.4]:23694 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S932347AbVHHXKL (ORCPT ); Mon, 8 Aug 2005 19:10:11 -0400 Date: Mon, 8 Aug 2005 16:08:44 -0700 From: Andrew Morton To: Mel Gorman Cc: linux-kernel@vger.kernel.org Subject: Re: How to reclaim inode pages on demand Message-Id: <20050808160844.04d1f7ac.akpm@osdl.org> In-Reply-To: References: X-Mailer: Sylpheed version 1.0.4 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Mel Gorman wrote: > > Hi, > > I am working on a direct reclaim strategy to free up large blocks of > contiguous pages. The part I have is working fine, but I am finding a > hundreds of pages that are being used for inodes that I need to reclaim. I > tried purging the inode lists using a variation of prune_icache() but it > is not working out. > > Given a struct page, that one knows is an inode, can anyone suggest the > best way to find the inode using it and free it? Simple answer: invalidate_mapping_pages(page->mapping, start, end). Problem: races. If you pick a random page up off the LRU and start playing with its mapping, what stops that mapping from getting freed under your feet? If the caller has a ref on the inode (say, you came in via a syscall against an fd) then fine. But if you picked the page up off the LRU then to avoid super-rare oopses you'll need to pin the address_space somehow. One way is to a) lock the page, which pins the address_space. b) check that page->mapping is still non-NULL. Bale if it is. c) bump page->mapping->host->i_count d) unlock the page e) diddle away with the address_space. f) iput() the inode. But beware that iput() can do a *ton* of stuff, so you need to be not holding any locks and to not be called from any fancy contexts.