Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754697Ab2EVSiA (ORCPT ); Tue, 22 May 2012 14:38:00 -0400 Received: from acsinet15.oracle.com ([141.146.126.227]:44490 "EHLO acsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752617Ab2EVSh7 (ORCPT ); Tue, 22 May 2012 14:37:59 -0400 Date: Tue, 22 May 2012 14:31:19 -0400 From: Konrad Rzeszutek Wilk To: Seth Jennings Cc: Minchan Kim , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Dan Magenheimer , Nitin Gupta Subject: Re: [PATCH] zsmalloc: use unsigned long instead of void * Message-ID: <20120522183119.GA24107@phenom.dumpdata.com> References: <1337567013-4741-1-git-send-email-minchan@kernel.org> <4FBA4EE2.8050308@linux.vnet.ibm.com> <4FBB97B2.6050408@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4FBB97B2.6050408@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: ucsinet21.oracle.com [156.151.31.93] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1390 Lines: 36 On Tue, May 22, 2012 at 08:42:10AM -0500, Seth Jennings wrote: > On 05/21/2012 09:19 AM, Seth Jennings wrote: > > > On 05/20/2012 09:23 PM, Minchan Kim wrote: > > > >> We should use unsigned long as handle instead of void * to avoid any > >> confusion. Without this, users may just treat zs_malloc return value as > >> a pointer and try to deference it. > > > > > > I wouldn't have agreed with you about the need for this change as people > > should understand a void * to be the address of some data with unknown > > structure. > > > > However, I recently discussed with Dan regarding his RAMster project > > where he assumed that the void * would be an address, and as such, > > 4-byte aligned. So he has masked two bits into the two LSBs of the > > handle for RAMster, which doesn't work with zsmalloc since the handle is > > not an address. > > > > So really we do need to convey as explicitly as possible to the user > > that the handle is an _opaque_ value about which no assumption can be made. > > > Wasn't really clear here. All that to say, I think we do need this patch. That sounds like an Acked-by ? > > Thanks, > Seth -- 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/