From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: linux-next: manual merge of the akpm-current tree with the tip tree Date: Tue, 14 Jan 2014 07:15:05 -0800 Message-ID: <52D55479.9010802@zytor.com> References: <20140114155331.88d170d3c991b9465c23a537@canb.auug.org.au> <20140114125153.GY7572@laptop.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from terminus.zytor.com ([198.137.202.10]:50984 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751599AbaANPQJ (ORCPT ); Tue, 14 Jan 2014 10:16:09 -0500 In-Reply-To: <20140114125153.GY7572@laptop.programming.kicks-ass.net> Sender: linux-next-owner@vger.kernel.org List-ID: To: Peter Zijlstra , Stephen Rothwell Cc: Andrew Morton , Thomas Gleixner , Ingo Molnar , linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, Geert Uytterhoeven , Davidlohr Bueso On 01/14/2014 04:51 AM, Peter Zijlstra wrote: > On Tue, Jan 14, 2014 at 03:53:31PM +1100, Stephen Rothwell wrote: >> Hi Andrew, >> >> Today's linux-next merge of the akpm-current tree got a conflict in >> kernel/futex.c between commit a52b89ebb6d4 ("futexes: Increase hash table >> size for better performance") from the tip tree and commit 61beee6c76e5 >> ("futex: switch to USER_DS for futex test") from the akpm-current tree. >> >> @@@ -2869,10 -2748,13 +2871,13 @@@ >> * implementation, the non-functional ones will return >> * -ENOSYS. >> */ >> + fs = get_fs(); >> + set_fs(USER_DS); >> if (cmpxchg_futex_value_locked(&curval, NULL, 0, 0) == -EFAULT) >> futex_cmpxchg_enabled = 1; >> + set_fs(fs); >> > > This seems terribly broken, the *futex_value*() ops should not need > that; they are supposed to access userspace without any of that. > I am *guessing* that m68k is has get_fs() == KERNEL_DS at the point that futex_init() is called. This would seem a bit of a peculiarity to m68k, and as such it would seem like it would be better for it to belong in the m68k-specific code, but since futex_init() is init code and only called once anyway it shouldn't cause any harm... -hpa