Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932443AbWHHQJu (ORCPT ); Tue, 8 Aug 2006 12:09:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932444AbWHHQJu (ORCPT ); Tue, 8 Aug 2006 12:09:50 -0400 Received: from e33.co.us.ibm.com ([32.97.110.151]:35535 "EHLO e33.co.us.ibm.com") by vger.kernel.org with ESMTP id S932443AbWHHQJt (ORCPT ); Tue, 8 Aug 2006 12:09:49 -0400 Subject: Re: [PATCH] sys_getppid oopses on debug kernel (v2) From: Dave Hansen To: Kirill Korotaev Cc: Andrew Morton , Linux Kernel Mailing List , alan@lxorguk.ukuu.org.uk, muli@il.ibm.com, B.Steinbrink@gmx.de, stable@kernel.org In-Reply-To: <44D8B2C5.1080905@sw.ru> References: <44D8B2C5.1080905@sw.ru> Content-Type: text/plain Date: Tue, 08 Aug 2006 09:09:21 -0700 Message-Id: <1155053361.19249.60.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.4.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 722 Lines: 18 On Tue, 2006-08-08 at 19:50 +0400, Kirill Korotaev wrote: > sys_getppid() optimization can access a freed memory. > On kernels with DEBUG_SLAB turned ON, this results in Oops. > As Dave Hansen noted, this optimization is also unsafe > for memory hotplug. Yeah, I just tried coding up something to do a seqlock to note when tasks are freed, but it doesn't work. Unless somebody is really going crazy with getppid() on a very large system, this should be just fine. -- Dave - 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/