Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Fri, 22 Jun 2018 00:08:44 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Fenghua Yu <fenghua.yu@intel.com>
Cc:     Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
        "H. Peter Anvin" <hpa@linux.intel.com>,
        Ashok Raj <ashok.raj@intel.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Rafael Wysocki <rafael.j.wysocki@intel.com>,
        Tony Luck <tony.luck@intel.com>,
        Alan Cox <alan@linux.intel.com>,
        Ravi V Shankar <ravi.v.shankar@intel.com>,
        Arjan van de Ven <arjan@infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>
Subject: Re: [RFC PATCH 00/16] x86/split_lock: Enable #AC exception for split
 locked accesses
Message-ID: <20180621220844.GB2494@hirez.programming.kicks-ass.net>
References: <1527435965-202085-1-git-send-email-fenghua.yu@intel.com>
 <20180621193738.GA13636@worktop.programming.kicks-ass.net>
 <20180621201851.GC114883@romley-ivt3.sc.intel.com>
 <alpine.DEB.2.21.1806212223480.1591@nanos.tec.linutronix.de>
 <20180621220003.GD114883@romley-ivt3.sc.intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20180621220003.GD114883@romley-ivt3.sc.intel.com>
User-Agent: Mutt/1.10.0 (2018-05-17)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, Jun 21, 2018 at 03:00:03PM -0700, Fenghua Yu wrote:
> The control knob for kernel is to choose re-executing the faulting
> instruction (default) or kernel panic. Kernel panic may be useful in hard
> real time which has less tolerant to bad performance.

The kernel should never trigger this, ever. Any #AC is a plain bug and
should be fixed. So unconditional WARN+disable is suffient.