From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759150Ab3K1OvU (ORCPT ); Thu, 28 Nov 2013 09:51:20 -0500 Received: from mail-qa0-f45.google.com ([209.85.216.45]:63433 "EHLO mail-qa0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754631Ab3K1OvS (ORCPT ); Thu, 28 Nov 2013 09:51:18 -0500 Date: Thu, 28 Nov 2013 09:51:15 -0500 From: Tejun Heo To: Peter Zijlstra Cc: Oleg Nesterov , zhang.yi20@zte.com.cn, lkml , Tetsuo Handa , Ingo Molnar Subject: Re: [PATCH]: exec: avoid propagating PF_NO_SETAFFINITY into userspace child Message-ID: <20131128145115.GF3925@htj.dyndns.org> References: <20131127183117.GB13098@mtj.dyndns.org> <20131128091358.GH10022@twins.programming.kicks-ass.net> <20131128114542.GA3826@redhat.com> <20131128121748.GN10022@twins.programming.kicks-ass.net> <20131128133152.GA821@redhat.com> <20131128133947.GR10022@twins.programming.kicks-ass.net> <20131128141329.GB3925@htj.dyndns.org> <20131128143145.GT10022@twins.programming.kicks-ass.net> <20131128143848.GD3925@htj.dyndns.org> <20131128144714.GV10022@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131128144714.GV10022@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 28, 2013 at 03:47:14PM +0100, Peter Zijlstra wrote: > Bah, windows mentality of we know better. > > If they do stupid they get stupid; the only thing we should be concerned > about is correctness, they shouldn't be able to crash the system. It isn't about that we know better but more that we do not want to leak implementation details to userland. "Whatever isn't crashing is okay" doesn't work because we aren't supposed to change behaviors which are depended upon from userland. Unless what's exposed is actively managed, we end up being locked into specific unintended characteristics of the current implementation. It hurts both the kernel and userland. We end up having to hack around silly constraints in the future and userland gets surprised when such hacks inevitably falls apart in corner cases. So, no, it's not about which part knows better or windows mentaility. It's about having proper separation between implementation details and exposed interface. Thanks. -- tejun