Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755535Ab3JISyH (ORCPT ); Wed, 9 Oct 2013 14:54:07 -0400 Received: from mail-vc0-f178.google.com ([209.85.220.178]:52135 "EHLO mail-vc0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754976Ab3JISyG (ORCPT ); Wed, 9 Oct 2013 14:54:06 -0400 MIME-Version: 1.0 In-Reply-To: <20131009181613.GW30970@tucnak.zalov.cz> References: <20131005234430.GA22485@localhost> <20131008143400.GA14721@redhat.com> <20131009080459.GA2298@localhost> <20131009124310.GA11769@redhat.com> <20131009140734.GH3081@twins.programming.kicks-ass.net> <20131009143359.GU26785@twins.programming.kicks-ass.net> <20131009144656.GV26785@twins.programming.kicks-ass.net> <20131009181613.GW30970@tucnak.zalov.cz> Date: Wed, 9 Oct 2013 11:54:04 -0700 X-Google-Sender-Auth: tRxZyQIs1kbB2SWwlmqGdWrV3gI Message-ID: Subject: Re: [x86] BUG: unable to handle kernel paging request at 00740060 From: Linus Torvalds To: Jakub Jelinek Cc: Peter Zijlstra , Oleg Nesterov , Fengguang Wu , Ingo Molnar , Linux Kernel Mailing List , Richard Henderson Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 910 Lines: 21 On Wed, Oct 9, 2013 at 11:16 AM, Jakub Jelinek wrote: > > Confirmed as gcc bug, filed http://gcc.gnu.org/PR58670 > Seems all of 4.[6-9] miscompile it. Will have a look tomorrow > unless somebody beats me to it. But historically, the case where > asm goto labels jump to fallthru basic block had numerous problems in the > past. Ok, so it isn't even specific for x86-32, because your test-case shows the bug for me on 64-bit too. Apparently we just have a harder time hitting it in practice in the kernel on x86-64./ Too bad. It makes me nervous about all our _traditional_ uses of asm goto too, never mind the new ones.. Linus -- 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/