Re: [PATCH 2/4] mm: introduce mm_forbids_zeropage function

From: Andrew Morton
Date: Wed Oct 22 2014 - 15:22:30 EST


On Wed, 22 Oct 2014 13:09:28 +0200 Dominik Dingel <dingel@xxxxxxxxxxxxxxxxxx> wrote:

> Add a new function stub to allow architectures to disable for
> an mm_structthe backing of non-present, anonymous pages with
> read-only empty zero pages.
>
> ...
>
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -56,6 +56,10 @@ extern int sysctl_legacy_va_layout;
> #define __pa_symbol(x) __pa(RELOC_HIDE((unsigned long)(x), 0))
> #endif
>
> +#ifndef mm_forbids_zeropage
> +#define mm_forbids_zeropage(X) (0)
> +#endif

Can we document this please? What it does, why it does it. We should
also specify precisely which arch header file is responsible for
defining mm_forbids_zeropage.


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