Re: [PATCH 10/10] arch: fix has_transparent_hugepage()

[David Miller]

From: Hugh Dickins <hughd@xxxxxxxxxx>
Date: Tue, 5 Apr 2016 14:02:49 -0700 (PDT)

> I've just discovered that the useful-sounding has_transparent_hugepage()
> is actually an architecture-dependent minefield: on some arches it only
> builds if CONFIG_TRANSPARENT_HUGEPAGE=y, on others it's also there when
> not, but on some of those (arm and arm64) it then gives the wrong answer;
> and on mips alone it's marked __init, which would crash if called later
> (but so far it has not been called later).
> 
> Straighten this out: make it available to all configs, with a sensible
> default in asm-generic/pgtable.h, removing its definitions from those
> arches (arc, arm, arm64, sparc, tile) which are served by the default,
> adding #define has_transparent_hugepage has_transparent_hugepage to those
> (mips, powerpc, s390, x86) which need to override the default at runtime,
> and removing the __init from mips (but maybe that kind of code should be
> avoided after init: set a static variable the first time it's called).
> 
> Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>

Acked-by: David S. Miller <davem@xxxxxxxxxxxxx>