From fd8cfd3000191cb7f5b9ea8640bd46181f6b4b74 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Thu, 19 May 2016 17:13:00 -0700 Subject: arch: fix has_transparent_hugepage() 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 Cc: "Kirill A. Shutemov" Cc: Andrea Arcangeli Cc: Andres Lagar-Cavilla Cc: Yang Shi Cc: Ning Qu Cc: Mel Gorman Cc: Konstantin Khlebnikov Acked-by: David S. Miller Acked-by: Vineet Gupta [arch/arc] Acked-by: Gerald Schaefer [arch/s390] Acked-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/mips/mm/tlb-r4k.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) (limited to 'arch/mips/mm') diff --git a/arch/mips/mm/tlb-r4k.c b/arch/mips/mm/tlb-r4k.c index c17d7627f872..2d93b63cf830 100644 --- a/arch/mips/mm/tlb-r4k.c +++ b/arch/mips/mm/tlb-r4k.c @@ -400,19 +400,20 @@ void add_wired_entry(unsigned long entrylo0, unsigned long entrylo1, #ifdef CONFIG_TRANSPARENT_HUGEPAGE -int __init has_transparent_hugepage(void) +int has_transparent_hugepage(void) { - unsigned int mask; - unsigned long flags; - - local_irq_save(flags); - write_c0_pagemask(PM_HUGE_MASK); - back_to_back_c0_hazard(); - mask = read_c0_pagemask(); - write_c0_pagemask(PM_DEFAULT_MASK); + static unsigned int mask = -1; - local_irq_restore(flags); + if (mask == -1) { /* first call comes during __init */ + unsigned long flags; + local_irq_save(flags); + write_c0_pagemask(PM_HUGE_MASK); + back_to_back_c0_hazard(); + mask = read_c0_pagemask(); + write_c0_pagemask(PM_DEFAULT_MASK); + local_irq_restore(flags); + } return mask == PM_HUGE_MASK; } -- cgit