From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752908AbbCSPWX (ORCPT ); Thu, 19 Mar 2015 11:22:23 -0400 Received: from cantor2.suse.de ([195.135.220.15]:51342 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750933AbbCSPWS (ORCPT ); Thu, 19 Mar 2015 11:22:18 -0400 Date: Thu, 19 Mar 2015 16:22:16 +0100 Message-ID: From: Takashi Iwai To: Denys Vlasenko Cc: Denys Vlasenko , Andy Lutomirski , Jiri Kosina , Linus Torvalds , Stefan Seyfried , X86 ML , LKML , Tejun Heo Subject: Re: PANIC: double fault, error_code: 0x0 in 4.0.0-rc3-2, kvm related? In-Reply-To: References: <5505400B.8050300@message-id.googlemail.com> <5509CBF7.3040602@message-id.googlemail.com> <5509F161.3010101@redhat.com> <550AABCB.9040502@redhat.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/24.4 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org At Thu, 19 Mar 2015 15:55:26 +0100, Takashi Iwai wrote: > > At Thu, 19 Mar 2015 14:47:12 +0100, > Takashi Iwai wrote: > > > > At Thu, 19 Mar 2015 13:48:56 +0100, > > Denys Vlasenko wrote: > > > > > > Having no more ideas at the moment, here is a tarball of 13 patches > > > of commits touching entry_64.S up to 4.0.0-rc1. > > > > > > x0001.patch is the latest, x0015.patch is the oldest. > > > > > > Patches 0003 and 0008 are not there since 0003 is empty merge patch > > > and 0008 does some PCI fixup. > > > > > > If this breakage is recent, it ought to be one of these. > > > Most of them do some non-trivial surgery. > > > > > > Even though I did not spot anything suspicious in them, > > > entry.S is notorious for subtle breakage. > > > > > > Try reverting them in sequence starting from x0001.patch > > > and see reverting which one makes crash disappear. > > > > OK, I'm going to check these git series. > > Reverting the commit > 96b6352c12711d5c0bb7157f49c92580248e8146 > x86_64, entry: Remove the syscall exit audit and schedule optimizations > > seems enough. After reverting this one, the machine runs stable with > the kvm stress test. > > (I'll keep test running for a while; at the previous bisection, I hit > the bug right after posting the mail ;) It survived long enough, so this looks like the spot. Also, I checked the patch below instead of reverting the commit, and this seems working, too. Takashi diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 1d74d161687c..5340ac7f88a9 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -364,12 +364,12 @@ system_call_fastpath: * Has incomplete stack frame and undefined top of stack. */ ret_from_sys_call: - testl $_TIF_ALLWORK_MASK,TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET) - jnz int_ret_from_sys_call_fixup /* Go the the slow path */ - LOCKDEP_SYS_EXIT DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF + testl $_TIF_ALLWORK_MASK,TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET) + jnz int_ret_from_sys_call_fixup /* Go the the slow path */ + CFI_REMEMBER_STATE /* * sysretq will re-enable interrupts: