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Date: Tue, 22 Apr 2014 16:35:29 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Ingo Molnar <mingo@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
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Subject: Why do we set _PAGE_DIRTY for page tables?
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I just noticed this:

#define _PAGE_TABLE     (_PAGE_PRESENT | _PAGE_RW | _PAGE_USER |       \
                         _PAGE_ACCESSED | _PAGE_DIRTY)
#define _KERNPG_TABLE   (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED |   \
                         _PAGE_DIRTY)

Is there a reason we set _PAGE_DIRTY for page tables?  It has no
function, but doesn't do any harm either (the dirty bit is ignored for
page tables)... it just looks funny to me.

	-hpa