Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263418AbTH0OoO (ORCPT ); Wed, 27 Aug 2003 10:44:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263410AbTH0OoO (ORCPT ); Wed, 27 Aug 2003 10:44:14 -0400 Received: from bay-bridge.veritas.com ([143.127.3.10]:39948 "EHLO mtvmime02.veritas.com") by vger.kernel.org with ESMTP id S263418AbTH0On6 (ORCPT ); Wed, 27 Aug 2003 10:43:58 -0400 Date: Wed, 27 Aug 2003 14:45:37 +0100 (BST) From: Hugh Dickins X-X-Sender: hugh@localhost.localdomain To: Ingo Oeser cc: Jaroslav Kysela , "linux-kernel@vger.kernel.org" , Subject: Re: Strange memory usage reporting In-Reply-To: <20030827095241.D639@nightmaster.csn.tu-chemnitz.de> Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1319 Lines: 29 On Wed, 27 Aug 2003, Ingo Oeser wrote: > On Tue, Aug 26, 2003 at 06:03:14PM +0100, Hugh Dickins wrote: > > Which is the driver involved? Though it's not wrong to give do_no_page > > a Reserved page, beware of the the page->count accounting: while it's > > Reserved, get_page or page_cache_get raises the count, but put_page > > or page_cache_release does not decrement it - very easy to end up > > with the page never freed. > > Why is this so asymetric? I would understand ignoring these pages > in the freeing logic, but why exclude them also from refcounting? I don't think there's a _good_ reason, it just evolved that way. The real answer is to get rid of PageReserved completely, which I'll embark on again in 2.7 (I did start a couple of times in 2.5, but each time it was too late). There was a halfway-house suggestion in 2.5 about three months ago, inspired (as usual) by Reserved page problems in AIO's get_user_pages, to do as you suggest: submit them to normal refcounting. I don't know what became of that, I didn't have much time to get involved. Hugh - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/