linux-kernel - Re: [PATCH v2 3/4] x86/split_lock: Handle #AC exception for split lock

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Message-ID: <20180629171641.GM18979@romley-ivt3.sc.intel.com>
Date:   Fri, 29 Jun 2018 10:16:42 -0700
From:   Fenghua Yu <fenghua.yu@...el.com>
To:     "Luck, Tony" <tony.luck@...el.com>
Cc:     "Hansen, Dave" <dave.hansen@...el.com>,
        "Yu, Fenghua" <fenghua.yu@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, H Peter Anvin <hpa@...or.com>,
        "Raj, Ashok" <ashok.raj@...el.com>,
        Alan Cox <alan@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        "Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
        "Shankar, Ravi V" <ravi.v.shankar@...el.com>,
        linux-kernel <linux-kernel@...r.kernel.org>, x86 <x86@...nel.org>
Subject: Re: [PATCH v2 3/4] x86/split_lock: Handle #AC exception for split
 lock

On Fri, Jun 29, 2018 at 09:33:54AM -0700, Luck, Tony wrote:
> >> +	WARN_ONCE(1, "A split lock issue is detected. Please FIX it\n");
> >
> > But, warning here is also not super useful.  Shouldn't we be dumping out
> > the info in 'regs' instead of the current context?  We don't care about
> > the state in the #AC handler, we care about 'regs'.

But WARN dump not only the state in the #AC handler, but also dump the regs
in the current context. And WARN dumps stack.

> 
> Maybe:
> 
> 	WARN_ONCE(1, "split lock detected at %pF\n", regs[EIP]);

Should we dump redundant regs info while WARN shows them all already?

Thanks.

-Fenghua