From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1752893AbdKWPaE (ORCPT <rfc822;w@1wt.eu>);
        Thu, 23 Nov 2017 10:30:04 -0500
Received: from mail.kernel.org ([198.145.29.99]:60730 "EHLO mail.kernel.org"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1752204AbdKWPaC (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 23 Nov 2017 10:30:02 -0500
DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 45ED0219A1
Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org
Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=luto@kernel.org
X-Google-Smtp-Source: AGs4zMYhMkPFOycEFhJNFrvSj9YyPEsGN9jidDROkMxYGbvQiq6VfuI5UyhNVdCHIYnPrpbalMcGDEo708HTPUfTHUA=
MIME-Version: 1.0
In-Reply-To: <20171123065828.dfzqe5cxfzlc2bcf@gmail.com>
References: <cover.1511325444.git.luto@kernel.org> <20171122062257.ivp5fbcy2k4mlfdm@gmail.com>
 <CALCETrVvpNVzixzAubip8-=8v=gE+Z_0CyXX117dmdbeXozEVQ@mail.gmail.com>
 <20171123062117.bztoxdqd2iv7ipdn@gmail.com> <20171123064414.hg7etp7iiis54ira@gmail.com>
 <20171123065828.dfzqe5cxfzlc2bcf@gmail.com>
From: Andy Lutomirski <luto@kernel.org>
Date: Thu, 23 Nov 2017 07:29:40 -0800
X-Gmail-Original-Message-ID: <CALCETrXcUCtx5xFpMuNwacJxj1ktoWO=gso_C4dLd+JDAZBsvA@mail.gmail.com>
Message-ID: <CALCETrXcUCtx5xFpMuNwacJxj1ktoWO=gso_C4dLd+JDAZBsvA@mail.gmail.com>
Subject: Re: [PATCH v2 00/18] Entry stack switching
To: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, X86 ML <x86@kernel.org>,
        Borislav Petkov <bpetkov@suse.de>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Brian Gerst <brgerst@gmail.com>, Dave Hansen <dave.hansen@intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wed, Nov 22, 2017 at 10:58 PM, Ingo Molnar <mingo@kernel.org> wrote:
>
> * Ingo Molnar <mingo@kernel.org> wrote:
>
>>
>> * Ingo Molnar <mingo@kernel.org> wrote:
>>
>> > > Anyway, I booted your config (more or less -- I munged it through
>> > > virtme-configkernel --update first) with 17 vCPUs and it seems fine.
>> > > Is the issue reliable enough to bisect?
>> >
>> > Ok, it should be bisectable, will try to bisect it.
>>
>> The latestest entry-stack code appears to be working fine though.
>>
>> So one of the below fixes from yesterday appears to have done the trick.
>>
>> I'll re-test today to make sure: maybe it's more sporadic than I thought, in one
>> of the bootups I got the do_IRQ warning only once, in half a day of uptime.
>
> I re-tested and it all seems fine now. I suspect it got fixed by:
>
>   ca37e57bbe0c: x86/entry/64: Add missing irqflags tracing to native_load_gs_index()
>
> still it is weird, because I boot that system with latest -tip on a daily basis,
> and don't remember having seen that warning.
>
> Do you have any theory for why the entry stack changes would uncover this bug?

No.  I also don't see why it would have anything to do with irqflag
tracing.  As far as I know, the unhandled IRQ warning has nothing to
do with tracing or lockdep.