From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754045AbdJSSQ6 (ORCPT ); Thu, 19 Oct 2017 14:16:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53920 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751762AbdJSSQ4 (ORCPT ); Thu, 19 Oct 2017 14:16:56 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com A0C5C83F3E Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=jpoimboe@redhat.com Date: Thu, 19 Oct 2017 13:16:55 -0500 From: Josh Poimboeuf To: Andrei Vagin Cc: Ingo Molnar , linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, peterz@infradead.org, hpa@zytor.com, tglx@linutronix.de Subject: Re: [2/2] x86/unwind: Make CONFIG_UNWINDER_ORC=y the default in kconfig for 64-bit Message-ID: <20171019181655.7yjgxuebkqzzcz4f@treble> References: <9b1237bbe7244ed9cdf8db2dcb1253e37e1c341e.1507924831.git.jpoimboe@redhat.com> <20171019165103.GA15123@outlook.office365.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20171019165103.GA15123@outlook.office365.com> User-Agent: Mutt/1.6.0.1 (2016-04-01) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Thu, 19 Oct 2017 18:16:56 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 19, 2017 at 09:51:04AM -0700, Andrei Vagin wrote: > Hi, > > We run CRIU tests for tip/auto-latest regularly, and a few days ago our > test job started to detect this warning in a kernel log: > > [ 44.235786] WARNING: can't dereference iret registers at ffff8801c5f17fe0 for ip ffffffff95f0d94b > > What does it mean? How critical is it? > > Our test job fails if it detects any warning in a kernel log. Maybe we > need to investigate reasons of this warning and try to eliminate it? > > Here are logs: > https://travis-ci.org/avagin/linux/jobs/289676634 I think it means the unwinder found some bad ORC unwinder metadata. Any chance you have access to the kernel binary? I need to know what code corresponds to that ffffffff95f0d94b address. Or if you can reproduce with the following patch, that should help: diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c index 570b70d3f604..95b633f0ce51 100644 --- a/arch/x86/kernel/unwind_orc.c +++ b/arch/x86/kernel/unwind_orc.c @@ -448,7 +448,7 @@ bool unwind_next_frame(struct unwind_state *state) case ORC_TYPE_REGS_IRET: if (!deref_stack_regs(state, sp, &state->ip, &state->sp, false)) { - orc_warn("can't dereference iret registers at %p for ip %p\n", + orc_warn("can't dereference iret registers at %p for ip %pB\n", (void *)sp, (void *)orig_ip); goto done; }