Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751659AbaG1Sl4 (ORCPT ); Mon, 28 Jul 2014 14:41:56 -0400 Received: from ud10.udmedia.de ([194.117.254.50]:36426 "EHLO mail.ud10.udmedia.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751213AbaG1Slz (ORCPT ); Mon, 28 Jul 2014 14:41:55 -0400 Date: Mon, 28 Jul 2014 20:41:53 +0200 From: Markus Trippelsdorf To: Linus Torvalds Cc: Alexei Starovoitov , "Frank Ch. Eigler" , Steven Rostedt , Michel =?iso-8859-1?Q?D=E4nzer?= , Jakub Jelinek , Linux Kernel Mailing List , Debian GCC Maintainers , Debian Kernel Team Subject: Re: Random panic in load_balance() with 3.16-rc Message-ID: <20140728184153.GB22904@x4> References: <20140726193557.GA21842@x4> <20140726201914.GB21842@x4> <20140728172737.GA17598@pg-vmw-gw1> <20140728180902.GA22904@x4> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014.07.28 at 11:28 -0700, Linus Torvalds wrote: > On Mon, Jul 28, 2014 at 11:09 AM, Markus Trippelsdorf > wrote: > > > > It shouldn't be too hard to implement a simple check for the bug in the > > next release. Just compile the gcc/testsuite/gcc.target/i386/pr61801.c > > testcase with -fcompare-debug. If gcc returns 0 then > > -fvar-tracking-assignments could safely be enabled again. > > We don't really have any good infrastructure for things like this, > though. We probably *should* have a way to generate config options by > compiler version, but right now we don't. We do random ugly things > from within Makefile shell escapes (see all the helpers for this we do > in scripts/Kbuild.include, for example), and we could add yet another > one. But this is a whole new level of "ugly hack". It would be better > if we could do things like this at config time, not at build-time with > Makefile hacks. > > Also, the test-case seems to be very sensitive to compiler options: it > passes with "-O", but fails with "-O2" or "-Os" for me. So I wonder > how reliable it is in the face of compiler version differences (ie is > it really robust wrt the bug actually being *fixed*, or is it a bit of > a happenstance) It is robust with -O2 and -Os for all supported series that I've checked: 4.8, 4.9 and 5.0. I haven't checked older releases. -- Markus -- 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/