linux-kernel - RE: [PATCH v10 6/6] x86/split_lock: Enable split lock detection by kernel parameter

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Message-ID: <3481175cbe14457a947f934343946d52@AcuMS.aculab.com>
Date:   Thu, 21 Nov 2019 17:43:51 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Ingo Molnar' <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
CC:     Fenghua Yu <fenghua.yu@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        H Peter Anvin <hpa@...or.com>,
        Tony Luck <tony.luck@...el.com>,
        Ashok Raj <ashok.raj@...el.com>,
        Ravi V Shankar <ravi.v.shankar@...el.com>,
        linux-kernel <linux-kernel@...r.kernel.org>, x86 <x86@...nel.org>
Subject: RE: [PATCH v10 6/6] x86/split_lock: Enable split lock detection by
 kernel parameter

From: Ingo Molnar
> Sent: 21 November 2019 17:12
> * Peter Zijlstra <peterz@...radead.org> wrote:
...
> > This feature MUST be default enabled, otherwise everything will
> > be/remain broken and we'll end up in the situation where you can't use
> > it even if you wanted to.
> 
> Agreed.

Before it can be enabled by default someone needs to go through the
kernel and fix all the code that abuses the 'bit' functions by using them
on int[] instead of long[].

I've only seen one fix go through for one use case of one piece of code
that repeatedly uses potentially misaligned int[] arrays for bitmasks.

	David

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