Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751728AbaG1SJK (ORCPT ); Mon, 28 Jul 2014 14:09:10 -0400 Received: from ud10.udmedia.de ([194.117.254.50]:58442 "EHLO mail.ud10.udmedia.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751681AbaG1SJF (ORCPT ); Mon, 28 Jul 2014 14:09:05 -0400 Date: Mon, 28 Jul 2014 20:09:02 +0200 From: Markus Trippelsdorf To: Alexei Starovoitov Cc: Linus Torvalds , "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: <20140728180902.GA22904@x4> References: <20140726193557.GA21842@x4> <20140726201914.GB21842@x4> <20140728172737.GA17598@pg-vmw-gw1> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140728172737.GA17598@pg-vmw-gw1> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014.07.28 at 10:27 -0700, Alexei Starovoitov wrote: > On Mon, Jul 28, 2014 at 09:45:45AM -0700, Linus Torvalds wrote: > > On Mon, Jul 28, 2014 at 5:26 AM, Frank Ch. Eigler wrote: > > > > > > Please note that the data produced by "-g -fvar-tracking" is consumed > > > by tools like systemtap, perf, crash, and makes a significant > > > difference to the observability of debug AND non-debug kernels. > > > > Yeah, and compared to having a buggy kernel, I care exactly this much: "". > > It's not pretty, but adding it unconditionally was the right thing to do. > Black listing compiler versions is too fragile. > Look at the flip side: now size of build dir will be much smaller :) 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. Here's the testcase: int a, b, c; void fn1 () { int d; if (fn2 () && !0) { b = ( { int e; fn3 (); switch (0) default: asm volatile("" : "=a"(e) : "0"(a), "i"(0)); e; }); d = b; } c = d; } -- 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/