linux-kernel - Re: [patch V3 10/11] x86/mm/cpa: Do the range check early

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Date:   Fri, 21 Sep 2018 13:26:59 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Peter Zijlstra <peterz@...radead.org>,
        Bin Yang <bin.yang@...el.com>,
        Mark Gross <mark.gross@...el.com>
Subject: Re: [patch V3 10/11] x86/mm/cpa: Do the range check early

On 09/17/2018 07:29 AM, Thomas Gleixner wrote:
> To avoid excessive 4k wise checks in the common case do a quick check first
> whether the requested new page protections conflict with a static
> protection area in the large page. If there is no conflict then the
> decision whether to preserve or to split the page can be made immediately.
> 
> If the requested range covers the full large page, preserve it. Otherwise
> split it up. No point in doing a slow crawl in 4k steps.

That's the big one...

Reviewed-by: Dave Hansen <dave.hansen@...el.com>