From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755808AbZE0WfH (ORCPT ); Wed, 27 May 2009 18:35:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753365AbZE0We5 (ORCPT ); Wed, 27 May 2009 18:34:57 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:35942 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753339AbZE0We5 (ORCPT ); Wed, 27 May 2009 18:34:57 -0400 Date: Thu, 28 May 2009 00:34:21 +0200 From: Ingo Molnar To: Rik van Riel Cc: "Larry H." , linux-kernel@vger.kernel.org, Linus Torvalds , linux-mm@kvack.org, Ingo Molnar , Alan Cox , pageexec@freemail.hu Subject: Re: [patch 0/5] Support for sanitization flag in low-level page allocator Message-ID: <20090527223421.GA9503@elte.hu> References: <20090520183045.GB10547@oblivion.subreption.com> <4A15A8C7.2030505@redhat.com> <20090522073436.GA3612@elte.hu> <20090522113809.GB13971@oblivion.subreption.com> <20090523124944.GA23042@elte.hu> <4A187BDE.5070601@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A187BDE.5070601@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Rik van Riel wrote: > Ingo Molnar wrote: > >> What you are missing is that your patch makes _no technical >> sense_ if you allow the same information to leak over the kernel >> stack. Kernel stacks can be freed and reused, swapped out and >> thus 'exposed'. > > Kernel stacks may be freed and reused, but Larry's latest patch > takes care of that by clearing them at page free time. > > As for being swapped out - I do not believe that kernel stacks can > ever be swapped out in Linux. yes, i referred to that as an undesirable option - because it slows down pthread_create() quite substantially. This needs before/after pthread_create() benchmark results. Ingo From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id B29D96B00A4 for ; Wed, 27 May 2009 18:34:01 -0400 (EDT) Date: Thu, 28 May 2009 00:34:21 +0200 From: Ingo Molnar Subject: Re: [patch 0/5] Support for sanitization flag in low-level page allocator Message-ID: <20090527223421.GA9503@elte.hu> References: <20090520183045.GB10547@oblivion.subreption.com> <4A15A8C7.2030505@redhat.com> <20090522073436.GA3612@elte.hu> <20090522113809.GB13971@oblivion.subreption.com> <20090523124944.GA23042@elte.hu> <4A187BDE.5070601@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A187BDE.5070601@redhat.com> Sender: owner-linux-mm@kvack.org To: Rik van Riel Cc: "Larry H." , linux-kernel@vger.kernel.org, Linus Torvalds , linux-mm@kvack.org, Ingo Molnar , Alan Cox , pageexec@freemail.hu List-ID: * Rik van Riel wrote: > Ingo Molnar wrote: > >> What you are missing is that your patch makes _no technical >> sense_ if you allow the same information to leak over the kernel >> stack. Kernel stacks can be freed and reused, swapped out and >> thus 'exposed'. > > Kernel stacks may be freed and reused, but Larry's latest patch > takes care of that by clearing them at page free time. > > As for being swapped out - I do not believe that kernel stacks can > ever be swapped out in Linux. yes, i referred to that as an undesirable option - because it slows down pthread_create() quite substantially. This needs before/after pthread_create() benchmark results. Ingo -- 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