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 S1752327AbdH2Lx6 (ORCPT <rfc822;w@1wt.eu>);
        Tue, 29 Aug 2017 07:53:58 -0400
Received: from mga02.intel.com ([134.134.136.20]:16184 "EHLO mga02.intel.com"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1751673AbdH2Lx4 (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 29 Aug 2017 07:53:56 -0400
X-ExtLoop1: 1
X-IronPort-AV: E=Sophos;i="5.41,444,1498546800"; 
   d="scan'208";a="129426489"
From: Alexander Shishkin <alexander.shishkin@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        Arjan van de Ven <arjan@linux.intel.com>,
        Borislav Petkov <bp@alien8.de>,
        Richard Weinberger <richard.weinberger@gmail.com>,
        Ingo Molnar <mingo@kernel.org>, linux-kernel@vger.kernel.org,
        Jason Wessel <jason.wessel@windriver.com>
Subject: Re: [PATCH] x86/debug: Handle warnings before the notifier chain
In-Reply-To: <20170724102140.yjmruyecl7gxg3q7@hirez.programming.kicks-ass.net>
References: <20170724100428.19173-1-alexander.shishkin@linux.intel.com> <20170724102140.yjmruyecl7gxg3q7@hirez.programming.kicks-ass.net>
User-Agent: Notmuch/0.23.7 (http://notmuchmail.org) Emacs/25.1.1 (x86_64-pc-linux-gnu)
Date: Tue, 29 Aug 2017 14:53:52 +0300
Message-ID: <87o9qyy4hb.fsf@ashishki-desk.ger.corp.intel.com>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Peter Zijlstra <peterz@infradead.org> writes:

> On Mon, Jul 24, 2017 at 01:04:28PM +0300, Alexander Shishkin wrote:
>> Commit
>> 
>>   9a93848fe787 ("x86/debug: Implement __WARN() using UD0")
>> 
>> turned warnings into UD0, but the fixup code only runs after the
>> notify_die() chain. This is a problem, in particular, with kgdb,
>> which kicks in as if it was a BUG().
>> 
>> Fix this by running the fixup code before the notifier chain in
>> the invalid op handler path.
>
> So arguable it might be nice to have kgdb trap on a WARN, but it
> treating it as a BUG is obviously undesirable.
>
> Jason, what would you want kgdb to do here?

Ping.