From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757913Ab3BFTJa (ORCPT ); Wed, 6 Feb 2013 14:09:30 -0500 Received: from mail-da0-f44.google.com ([209.85.210.44]:54356 "EHLO mail-da0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754619Ab3BFTJ1 (ORCPT ); Wed, 6 Feb 2013 14:09:27 -0500 Date: Wed, 6 Feb 2013 11:09:24 -0800 From: Greg KH To: Dan Magenheimer Cc: devel@linuxdriverproject.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, ngupta@vflare.org, konrad.wilk@oracle.com, sjenning@linux.vnet.ibm.com, minchan@kernel.org Subject: Re: [PATCH] staging/zcache: Fix/improve zcache writeback code, tie to a config option Message-ID: <20130206190924.GB32275@kroah.com> References: <1360175261-13287-1-git-send-email-dan.magenheimer@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1360175261-13287-1-git-send-email-dan.magenheimer@oracle.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 06, 2013 at 10:27:41AM -0800, Dan Magenheimer wrote: > It was observed by Andrea Arcangeli in 2011 that zcache can get "full" > and there must be some way for compressed swap pages to be (uncompressed > and then) sent through to the backing swap disk. A prototype of this > functionality, called "unuse", was added in 2012 as part of a major update > to zcache (aka "zcache2"), but was left unfinished due to the unfortunate > temporary fork of zcache. > > This earlier version of the code had an unresolved memory leak > and was anyway dependent on not-yet-upstream frontswap and mm changes. > The code was meanwhile adapted by Seth Jennings for similar > functionality in zswap (which he calls "flush"). Seth also made some > clever simplifications which are herein ported back to zcache. As a > result of those simplifications, the frontswap changes are no longer > necessary, but a slightly different (and simpler) set of mm changes are > still required [1]. The memory leak is also fixed. > > Due to feedback from akpm in a zswap thread, this functionality in zcache > has now been renamed from "unuse" to "writeback". > > Although this zcache writeback code now works, there are open questions > as how best to handle the policy that drives it. As a result, this > patch also ties writeback to a new config option. And, since the > code still depends on not-yet-upstreamed mm patches, to avoid build > problems, the config option added by this patch temporarily depends > on "BROKEN"; this config dependency can be removed in trees that > contain the necessary mm patches. I'll wait for those options to be in Linus's tree before accepting a patch like this, sorry. greg k-h