From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id C15556B005C for ; Thu, 28 May 2009 05:08:43 -0400 (EDT) Date: Thu, 28 May 2009 11:08:36 +0200 From: Ingo Molnar Subject: Re: [patch 0/5] Support for sanitization flag in low-level page allocator Message-ID: <20090528090836.GB6715@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> <20090527223421.GA9503@elte.hu> <20090528072702.796622b6@lxorguk.ukuu.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090528072702.796622b6@lxorguk.ukuu.org.uk> Sender: owner-linux-mm@kvack.org To: Alan Cox Cc: Rik van Riel , "Larry H." , linux-kernel@vger.kernel.org, Linus Torvalds , linux-mm@kvack.org, Ingo Molnar , pageexec@freemail.hu, Linus Torvalds List-ID: * Alan Cox wrote: > > > 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. > > kernel stacks can end up places you don't expect on hypervisor > based systems. > > In most respects the benchmarks are pretty irrelevant - wiping > stuff has a performance cost, but its the sort of thing you only > want to do when you have a security requirement that needs it. At > that point the performance is secondary. Bechmarks, of course, are not irrelevant _at all_. So i'm asking for this "clear kernel stacks on freeing" aspect to be benchmarked thoroughly, as i expect it to have a negative impact - otherwise i'm NAK-ing this. Please Cc: me to measurements results. Thanks, 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