From: Theodore Tso Subject: Re: [PATCH] resolve duplicate flag no for PG_lazyfree Date: Mon, 14 May 2007 14:06:19 -0400 Message-ID: <20070514180618.GB9399@thunk.org> References: <379110250.28666@ustc.edu.cn> <20070513224630.3cd0cb54.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Fengguang Wu , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Rik van Riel , "linux-ext4@vger.kernel.org" To: Andrew Morton Return-path: Content-Disposition: inline In-Reply-To: <20070513224630.3cd0cb54.akpm@linux-foundation.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Sun, May 13, 2007 at 10:46:30PM -0700, Andrew Morton wrote: > otoh, the intersection between pages which are PageBooked() and pages which > are PageLazyFree() should be zreo, so it'd be good to actually formalise > this reuse within the ext4 patches. > > otoh2, PageLazyFree() could have reused PG_owner_priv_1. > > Rik, Ted: any thoughts? We do need to scrimp on page flags: when we > finally run out, we're screwed. It makes sense to me. PG_lazyfree is currently only in -mm, right? I don't see it in my git tree. It would probably would be a good idea to make sure that we check to add some sanity checking code if it isn't there already that PG_lazyfree isn't already set when try to set PG_lazyfree (just in case there is a bug in the future which causes the should-never-happen case of trying lazy free a PageBooked page). - Ted