Re: [PATCH 3/9] parisc: Fix asm/mman.h regarding MAP_HUGETLB and MADV_XX flags

[Ben Hutchings <ben@decadent.org.uk>]

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On Fri, 2015-11-20 at 22:38 +0100, Helge Deller wrote:
> On parisc we have up to now never supported Huge Pages, even glibc did
> not defined MAP_HUGETLB for parisc. Since the Huge Page support is being
> added now, clean up existing definitions for MAP_HUGETLB and friends.
> 
> Drop lots of MADV_xxK_PAGES flags, which were never used and were
> designed for a patch which was never integrated into the Linux
> kernel. Instead move other MADV_ flags to make them more compatible to
> other linux architectures.

Changing the unimplemented values seems fine, but how can it be OK to
renumber MAP_GROWSUP, MADV_DONTDUMP and MADV_DODUMP?

Ben.

> Cc: stable@vger.kernel.org
> Signed-off-by: Helge Deller <deller@gmx.de>
> ---
>  arch/parisc/include/uapi/asm/mman.h | 29 ++++++++++-------------------
>  1 file changed, 10 insertions(+), 19 deletions(-)
> 
> diff --git a/arch/parisc/include/uapi/asm/mman.h b/arch/parisc/include/uapi/asm/mman.h
> index 294d251..9ac77f1 100644
> --- a/arch/parisc/include/uapi/asm/mman.h
> +++ b/arch/parisc/include/uapi/asm/mman.h
> @@ -19,11 +19,12 @@
>  #define MAP_EXECUTABLE> 	> 0x1000> 	> 	> /* mark it as an executable */
>  #define MAP_LOCKED> 	> 0x2000> 	> 	> /* pages are locked */
>  #define MAP_NORESERVE> 	> 0x4000> 	> 	> /* don't check for reservations */
> -#define MAP_GROWSDOWN> 	> 0x8000> 	> 	> /* stack-like segment */
> +#define MAP_GROWSDOWN> 	> 0x8000> 	> 	> /* x86 stack-like segment */
>  #define MAP_POPULATE> 	> 0x10000> 	> 	> /* populate (prefault) pagetables */
>  #define MAP_NONBLOCK> 	> 0x20000> 	> 	> /* do not block on IO */
> -#define MAP_STACK> 	> 0x40000> 	> 	> /* give out an address that is best suited for process/thread stacks */
> -#define MAP_HUGETLB> 	> 0x80000> 	> 	> /* create a huge page mapping */
> +#define MAP_HUGETLB> 	> 0x40000> 	> 	> /* create a huge page mapping */
> +#define MAP_GROWSUP> 	> 0x80000> 	> 	> /* parisc stack-like segment */
> +#define MAP_STACK> 	> MAP_GROWSUP> 	> /* give out an address that is best suited for process/thread stacks */
>  
>  #define MS_SYNC> 	> 	> 1> 	> 	> /* synchronous memory sync */
>  #define MS_ASYNC> 	> 2> 	> 	> /* sync memory asynchronously */
> @@ -46,25 +47,15 @@
>  #define MADV_DONTFORK> 	> 10> 	> 	> /* don't inherit across fork */
>  #define MADV_DOFORK> 	> 11> 	> 	> /* do inherit across fork */
>  
> -/* The range 12-64 is reserved for page size specification. */
> -#define MADV_4K_PAGES   12              /* Use 4K pages  */
> -#define MADV_16K_PAGES  14              /* Use 16K pages */
> -#define MADV_64K_PAGES  16              /* Use 64K pages */
> -#define MADV_256K_PAGES 18              /* Use 256K pages */
> -#define MADV_1M_PAGES   20              /* Use 1 Megabyte pages */
> -#define MADV_4M_PAGES   22              /* Use 4 Megabyte pages */
> -#define MADV_16M_PAGES  24              /* Use 16 Megabyte pages */
> -#define MADV_64M_PAGES  26              /* Use 64 Megabyte pages */
> +#define MADV_MERGEABLE   12> 	> 	> /* KSM may merge identical pages */
> +#define MADV_UNMERGEABLE 13> 	> 	> /* KSM may not merge identical pages */
>  
> -#define MADV_MERGEABLE   65> 	> 	> /* KSM may merge identical pages */
> -#define MADV_UNMERGEABLE 66> 	> 	> /* KSM may not merge identical pages */
> +#define MADV_HUGEPAGE> 	> 14> 	> 	> /* Worth backing with hugepages */
> +#define MADV_NOHUGEPAGE> 	> 15> 	> 	> /* Not worth backing with hugepages */
>  
> -#define MADV_HUGEPAGE> 	> 67> 	> 	> /* Worth backing with hugepages */
> -#define MADV_NOHUGEPAGE> 	> 68> 	> 	> /* Not worth backing with hugepages */
> -
> -#define MADV_DONTDUMP   69> 	> 	> /* Explicity exclude from the core dump,
> +#define MADV_DONTDUMP   16> 	> 	> /* Explicity exclude from the core dump,
>  > 	> 	> 	> 	> 	>    overrides the coredump filter bits */
> -#define MADV_DODUMP> 	> 70> 	> 	> /* Clear the MADV_NODUMP flag */
> +#define MADV_DODUMP> 	> 17> 	> 	> /* Clear the MADV_NODUMP flag */
>  
>  /* compatibility flags */
>  #define MAP_FILE> 	> 0
-- 
Ben Hutchings
If you seem to know what you are doing, you'll be given more to do.

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