Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753792Ab3JIOcc (ORCPT ); Wed, 9 Oct 2013 10:32:32 -0400 Received: from mail-ea0-f171.google.com ([209.85.215.171]:49609 "EHLO mail-ea0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752079Ab3JIOcb (ORCPT ); Wed, 9 Oct 2013 10:32:31 -0400 Date: Wed, 9 Oct 2013 16:32:26 +0200 From: Ingo Molnar To: Peter Zijlstra Cc: Oleg Nesterov , Fengguang Wu , Linus Torvalds , Linux Kernel Mailing List Subject: Re: [x86] BUG: unable to handle kernel paging request at 00740060 Message-ID: <20131009143226.GA24911@gmail.com> References: <20131005234430.GA22485@localhost> <20131008143400.GA14721@redhat.com> <20131009080459.GA2298@localhost> <20131009124310.GA11769@redhat.com> <20131009140734.GH3081@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131009140734.GH3081@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 Content-Length: 916 Lines: 27 * Peter Zijlstra wrote: > > This is what we are going to return. But note that -20(%ebp) was not > > initialized if TIF_NOTIFY_RESUME was already set, "jc .L2" skips .L5 > > above. IOW, in this case we seem to return a random value from stack. > > I think you're quite right, and I can confirm I can reproduce this with > gcc-4.8.1 and Wu's .config: > > [...] > > Once I force a x86_64 build using the 'same' config it goes away and > generates 'sensible' code again [...] So this at least opens up the possibility that we can create a not too painful quirk and only use the 'asm goto' optimization tricks on 64-bit kernels? Thanks, Ingo -- 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/