From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966987Ab3E2Uso (ORCPT ); Wed, 29 May 2013 16:48:44 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:50302 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966734Ab3E2Usi (ORCPT ); Wed, 29 May 2013 16:48:38 -0400 Date: Wed, 29 May 2013 13:48:35 -0700 From: Andrew Morton To: Seth Jennings Cc: Greg Kroah-Hartman , Nitin Gupta , Minchan Kim , Konrad Rzeszutek Wilk , Dan Magenheimer , Robert Jennings , Jenifer Hopper , Mel Gorman , Johannes Weiner , Rik van Riel , Larry Woodman , Benjamin Herrenschmidt , Dave Hansen , Joe Perches , Joonsoo Kim , Cody P Schafer , Hugh Dickens , Paul Mackerras , Heesub Shin , linux-mm@kvack.org, linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org Subject: Re: [PATCHv12 2/4] zbud: add to mm/ Message-Id: <20130529134835.58dd89774f47205da4a06202@linux-foundation.org> In-Reply-To: <20130529204236.GD428@cerebellum> References: <1369067168-12291-1-git-send-email-sjenning@linux.vnet.ibm.com> <1369067168-12291-3-git-send-email-sjenning@linux.vnet.ibm.com> <20130528145911.bd484cbb0bb7a27c1623c520@linux-foundation.org> <20130529154500.GB428@cerebellum> <20130529113434.b2ced4cc1e66c7a0a520d908@linux-foundation.org> <20130529204236.GD428@cerebellum> X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 29 May 2013 15:42:36 -0500 Seth Jennings wrote: > > > > I worry about any code which independently looks at the pageframe > > > > tables and expects to find page struts there. One example is probably > > > > memory_failure() but there are probably others. > > > > ^^ this, please. It could be kinda fatal. > > I'll look into this. > > The expected behavior is that memory_failure() should handle zbud pages in the > same way that it handles in-use slub/slab/slob pages and return -EBUSY. memory_failure() is merely an example of a general problem: code which reads from the memmap[] array and expects its elements to be of type `struct page'. Other examples might be memory hotplugging, memory leak checkers etc. I have vague memories of out-of-tree patches (bigphysarea?) doing this as well. It's a general problem to which we need a general solution. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx179.postini.com [74.125.245.179]) by kanga.kvack.org (Postfix) with SMTP id D3F0E6B0111 for ; Wed, 29 May 2013 16:48:38 -0400 (EDT) Date: Wed, 29 May 2013 13:48:35 -0700 From: Andrew Morton Subject: Re: [PATCHv12 2/4] zbud: add to mm/ Message-Id: <20130529134835.58dd89774f47205da4a06202@linux-foundation.org> In-Reply-To: <20130529204236.GD428@cerebellum> References: <1369067168-12291-1-git-send-email-sjenning@linux.vnet.ibm.com> <1369067168-12291-3-git-send-email-sjenning@linux.vnet.ibm.com> <20130528145911.bd484cbb0bb7a27c1623c520@linux-foundation.org> <20130529154500.GB428@cerebellum> <20130529113434.b2ced4cc1e66c7a0a520d908@linux-foundation.org> <20130529204236.GD428@cerebellum> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Seth Jennings Cc: Greg Kroah-Hartman , Nitin Gupta , Minchan Kim , Konrad Rzeszutek Wilk , Dan Magenheimer , Robert Jennings , Jenifer Hopper , Mel Gorman , Johannes Weiner , Rik van Riel , Larry Woodman , Benjamin Herrenschmidt , Dave Hansen , Joe Perches , Joonsoo Kim , Cody P Schafer , Hugh Dickens , Paul Mackerras , Heesub Shin , linux-mm@kvack.org, linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org On Wed, 29 May 2013 15:42:36 -0500 Seth Jennings wrote: > > > > I worry about any code which independently looks at the pageframe > > > > tables and expects to find page struts there. One example is probably > > > > memory_failure() but there are probably others. > > > > ^^ this, please. It could be kinda fatal. > > I'll look into this. > > The expected behavior is that memory_failure() should handle zbud pages in the > same way that it handles in-use slub/slab/slob pages and return -EBUSY. memory_failure() is merely an example of a general problem: code which reads from the memmap[] array and expects its elements to be of type `struct page'. Other examples might be memory hotplugging, memory leak checkers etc. I have vague memories of out-of-tree patches (bigphysarea?) doing this as well. It's a general problem to which we need a general solution. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org