Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751083AbdL3RJ4 (ORCPT ); Sat, 30 Dec 2017 12:09:56 -0500 Received: from mx1.redhat.com ([209.132.183.28]:49044 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750947AbdL3RJy (ORCPT ); Sat, 30 Dec 2017 12:09:54 -0500 Date: Sat, 30 Dec 2017 11:09:46 -0600 From: Josh Poimboeuf To: Alexander Tsoy Cc: Andy Lutomirski , Linus Torvalds , Toralf =?utf-8?Q?F=C3=B6rster?= , stable , Linux Kernel , the arch/x86 maintainers Subject: Re: 4.14.9 doesn't boot (regression) Message-ID: <20171230170946.ywnkxkeolwk3jm6w@treble> References: <33249a35-7d6a-f0f3-5a98-e6474f9366e3@gmx.de> <7A0A9B37-20FF-4B17-B4F5-D8B999269FC4@amacapital.net> <20171230034947.6jgk5t7c7jrl6dwg@treble> <1514623513.2379.1.camel@tsoy.me> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1514623513.2379.1.camel@tsoy.me> 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 [10.5.110.26]); Sat, 30 Dec 2017 17:09:54 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4445 Lines: 99 On Sat, Dec 30, 2017 at 11:45:13AM +0300, Alexander Tsoy wrote: > В Пт, 29/12/2017 в 21:49 -0600, Josh Poimboeuf пишет: > > On Fri, Dec 29, 2017 at 05:10:35PM -0700, Andy Lutomirski wrote: > > > (Also, Josh, the oops code should have printed the contents of the > > > struct pt_regs at the top of the DF stack.  Any idea why it > > > didn't?) > > > > Looking at one of the dumps: > > > >   [  392.774879] NMI backtrace for cpu 0 > >   [  392.774881] CPU: 0 PID: 1 Comm: init Not tainted 4.14.9-gentoo > > #1 > >   [  392.774881] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 > >   [  392.774882] task: ffff8802368b8000 task.stack: ffffc9000000c000 > >   [  392.774885] RIP: 0010:double_fault+0x0/0x30 > >   [  392.774886] RSP: 0000:ffffffffff527fd0 EFLAGS: 00000086 > >   [  392.774887] RAX: 000000003fc00000 RBX: 0000000000000001 RCX: > > 00000000c0000101 > >   [  392.774887] RDX: 00000000ffff8802 RSI: 0000000000000000 RDI: > > ffffffffff527f58 > >   [  392.774887] RBP: 0000000000000000 R08: 0000000000000000 R09: > > 0000000000000000 > >   [  392.774888] R10: 0000000000000000 R11: 0000000000000000 R12: > > ffffffff816ae726 > >   [  392.774888] R13: 0000000000000000 R14: 0000000000000000 R15: > > 0000000000000000 > >   [  392.774889] FS:  0000000000000000(0000) > > GS:ffff88023fc00000(0000) knlGS:0000000000000000 > >   [  392.774889] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > >   [  392.774890] CR2: ffffffffff526f08 CR3: 0000000235b48002 CR4: > > 00000000001606f0 > >   [  392.774892] Call Trace: > >   [  392.774894]  <#DF> > >   [  392.774897]  do_double_fault+0xb/0x140 > >   [  392.774898]   > > > > It should have at least printed the #DF iret frame registers, which I > > recently added support for in "x86/unwinder: Handle stack overflows > > more > > gracefully", which is in both 4.14.9 and 4.15-rc5. > > > > I think the missing iret regs are due to a bug in > > show_trace_log_lvl(), > > where if the unwind starts with two regs frames in a row, the second > > regs don't get printed. > > > > Alexander, would you mind reproducing again with the below patch?  It > > should still fail, but this time it should hopefully show another > > RIP/RSP/EFLAGS instead of the "do_double_fault+0xb/0x140" line. > > > > Yes, it works: > > [   23.058064] NMI backtrace for cpu 2 > [   23.058068] CPU: 2 PID: 1 Comm: init Not tainted 4.15.0-rc5+ #1 > [   23.058069] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), > BIOS 1.10.2-1.fc27 04/01/2014 > [   23.058074] RIP: 0010:double_fault+0x0/0x30 > [   23.058075] RSP: 0000:fffffe800005ffd0 EFLAGS: 00000086 > [   23.058077] RAX: 000000003fd00000 RBX: 0000000000000001 RCX: > 00000000c0000101 > [   23.058077] RDX: 00000000ffff9681 RSI: 0000000000000000 RDI: > fffffe800005ff58 > [   23.058078] RBP: 0000000000000000 R08: 0000000000000000 R09: > 0000000000000000 > [   23.058079] R10: 0000000000000000 R11: 0000000000000000 R12: > ffffffff92001426 > [   23.058080] R13: 0000000000000000 R14: 0000000000000000 R15: > 0000000000000000 > [   23.058083] FS:  0000000000000000(0000) GS:ffff96813fd00000(0000) > knlGS:0000000000000000 > [   23.058084] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [   23.058085] CR2: fffffe800005ef08 CR3: 0000000137a09000 CR4: > 00000000000406a0 > [   23.058089] Call Trace: > [   23.058101]  <#DF> > [   23.058104] RIP: 0010:do_double_fault+0xb/0x140 > [   23.058105] RSP: 0000:fffffe800005ef18 EFLAGS: 00010086 ORIG_RAX: > 0000000000000000 > [   23.058106] RAX: 000000003fd00000 RBX: 0000000000000001 RCX: > 00000000c0000101 > [   23.058107] RDX: 00000000ffff9681 RSI: 0000000000000000 RDI: > fffffe800005ff58 > [   23.058107] RBP: 0000000000000000 R08: 0000000000000000 R09: > 0000000000000000 > [   23.058108] R10: 0000000000000000 R11: 0000000000000000 R12: > ffffffff92001426 > [   23.058108] R13: 0000000000000000 R14: 0000000000000000 R15: > 0000000000000000 > [   23.058111]   > [   23.058111] Code: 05 00 00 48 89 e7 31 f6 e8 2e 8c 61 ff e9 69 06 00 > 00 e8 94 05 00 00 48 89 e7 31 f6 e8 1a 8c 61 ff e9 55 06 00 00 0f 1f 44 > 00 00 <0f> 1f 00 48 83 c4 88 e8 e4 04 00 00 48 89 e7 48 8b 74 24 78 48 That's better indeed, though still not quite right. It should have only shown a subset of those registers. One more bug to fix there... -- Josh