Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754120Ab0HWSAC (ORCPT ); Mon, 23 Aug 2010 14:00:02 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:52949 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751423Ab0HWSAB convert rfc822-to-8bit (ORCPT ); Mon, 23 Aug 2010 14:00:01 -0400 Subject: Re: [RFC] mlock/stack guard interaction fixup From: Peter Zijlstra To: Linus Torvalds Cc: Ian Jackson , Greg KH , Ian Campbell , linux-kernel@vger.kernel.org, stable@kernel.org, stable-review@kernel.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Jeremy Fitzhardinge In-Reply-To: References: <1282391770.29609.1223.camel@localhost.localdomain> <1282460275.11348.865.camel@localhost.localdomain> <1282462386.11348.871.camel@localhost.localdomain> <1282470917.11348.891.camel@localhost.localdomain> <20100822172548.GB8957@suse.de> <19570.38608.79434.179797@chiark.greenend.org.uk> <1282580751.2605.1997.camel@laptop> <19570.44367.719276.128881@chiark.greenend.org.uk> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Mon, 23 Aug 2010 19:59:45 +0200 Message-ID: <1282586385.2605.2119.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1439 Lines: 32 On Mon, 2010-08-23 at 10:34 -0700, Linus Torvalds wrote: > I suspect that if you use mlock for _any_ other reason than protecting > a particular very sensitive piece of information, you should use > mlockall(MCL_FUTURE). IOW, if you use mlock because you have realtime > issues, there is no excuse to ever use anything else, imho. And even > then, I guarantee that things like copy-on-write is going to be > "interesting". > > I realize that people hate mlockall() (and particularly MCL_FUTURE), > and yes, it's a bloated thing that you can't reasonably use on a large > process. But dammit, if you have RT issues, you shouldn't _have_ some > big bloated process. You should have a small statically linked server > that is RT, and nothing else. Us real-time people have been telling people to not use mlockall() at all. While small !glibc statically linked RT components using shared memory interfaces to !RT apps could work its not how people actually write their apps. They write big monolithic threaded apps where some threads are RT. [ in part because there doesn't seem to be a usable !glibc libpthread/librt implementation out there, in part because people use crap like Java-RT ] -- 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/