Re: [PATCH 2/3] mm: arch: Consolidate mmap hugetlb size encodings

[Michal Hocko]

On Mon 31-07-17 11:56:25, Mike Kravetz wrote:
> A non-default huge page size can be encoded in the flags argument
> of the mmap system call.  The definitions for these encodings are
> in arch specific header files.  However, all architectures use the
> same values.
> 
> Consolidate all the definitions in the primary user header file
> (uapi/linux/mman.h).  Include definitions for all known huge page
> sizes.  Use the generic encoding definitions in hugetlb_encode.h
> as the basis for these definitions.
> 
> Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>

Acked-by: Michal Hocko <mhocko@xxxxxxxx>

> ---
>  arch/alpha/include/uapi/asm/mman.h     | 11 -----------
>  arch/mips/include/uapi/asm/mman.h      | 11 -----------
>  arch/parisc/include/uapi/asm/mman.h    | 11 -----------
>  arch/powerpc/include/uapi/asm/mman.h   | 16 ----------------
>  arch/x86/include/uapi/asm/mman.h       |  3 ---
>  arch/xtensa/include/uapi/asm/mman.h    | 11 -----------
>  include/uapi/asm-generic/mman-common.h | 11 -----------
>  include/uapi/linux/mman.h              | 22 ++++++++++++++++++++++
>  8 files changed, 22 insertions(+), 74 deletions(-)
> 
> diff --git a/arch/alpha/include/uapi/asm/mman.h b/arch/alpha/include/uapi/asm/mman.h
> index 02760f6..13b52aa 100644
> --- a/arch/alpha/include/uapi/asm/mman.h
> +++ b/arch/alpha/include/uapi/asm/mman.h
> @@ -67,17 +67,6 @@
>  /* compatibility flags */
>  #define MAP_FILE	0
>  
> -/*
> - * When MAP_HUGETLB is set bits [26:31] encode the log2 of the huge page size.
> - * This gives us 6 bits, which is enough until someone invents 128 bit address
> - * spaces.
> - *
> - * Assume these are all power of twos.
> - * When 0 use the default page size.
> - */
> -#define MAP_HUGE_SHIFT	26
> -#define MAP_HUGE_MASK	0x3f
> -
>  #define PKEY_DISABLE_ACCESS	0x1
>  #define PKEY_DISABLE_WRITE	0x2
>  #define PKEY_ACCESS_MASK	(PKEY_DISABLE_ACCESS |\
> diff --git a/arch/mips/include/uapi/asm/mman.h b/arch/mips/include/uapi/asm/mman.h
> index 655e2fb..398eebc 100644
> --- a/arch/mips/include/uapi/asm/mman.h
> +++ b/arch/mips/include/uapi/asm/mman.h
> @@ -94,17 +94,6 @@
>  /* compatibility flags */
>  #define MAP_FILE	0
>  
> -/*
> - * When MAP_HUGETLB is set bits [26:31] encode the log2 of the huge page size.
> - * This gives us 6 bits, which is enough until someone invents 128 bit address
> - * spaces.
> - *
> - * Assume these are all power of twos.
> - * When 0 use the default page size.
> - */
> -#define MAP_HUGE_SHIFT	26
> -#define MAP_HUGE_MASK	0x3f
> -
>  #define PKEY_DISABLE_ACCESS	0x1
>  #define PKEY_DISABLE_WRITE	0x2
>  #define PKEY_ACCESS_MASK	(PKEY_DISABLE_ACCESS |\
> diff --git a/arch/parisc/include/uapi/asm/mman.h b/arch/parisc/include/uapi/asm/mman.h
> index 5979745..9cd0e8c 100644
> --- a/arch/parisc/include/uapi/asm/mman.h
> +++ b/arch/parisc/include/uapi/asm/mman.h
> @@ -64,17 +64,6 @@
>  #define MAP_FILE	0
>  #define MAP_VARIABLE	0
>  
> -/*
> - * When MAP_HUGETLB is set bits [26:31] encode the log2 of the huge page size.
> - * This gives us 6 bits, which is enough until someone invents 128 bit address
> - * spaces.
> - *
> - * Assume these are all power of twos.
> - * When 0 use the default page size.
> - */
> -#define MAP_HUGE_SHIFT	26
> -#define MAP_HUGE_MASK	0x3f
> -
>  #define PKEY_DISABLE_ACCESS	0x1
>  #define PKEY_DISABLE_WRITE	0x2
>  #define PKEY_ACCESS_MASK	(PKEY_DISABLE_ACCESS |\
> diff --git a/arch/powerpc/include/uapi/asm/mman.h b/arch/powerpc/include/uapi/asm/mman.h
> index ab45cc2..03c06ba 100644
> --- a/arch/powerpc/include/uapi/asm/mman.h
> +++ b/arch/powerpc/include/uapi/asm/mman.h
> @@ -29,20 +29,4 @@
>  #define MAP_STACK	0x20000		/* give out an address that is best suited for process/thread stacks */
>  #define MAP_HUGETLB	0x40000		/* create a huge page mapping */
>  
> -/*
> - * When MAP_HUGETLB is set, bits [26:31] of the flags argument to mmap(2),
> - * encode the log2 of the huge page size. A value of zero indicates that the
> - * default huge page size should be used. To use a non-default huge page size,
> - * one of these defines can be used, or the size can be encoded by hand. Note
> - * that on most systems only a subset, or possibly none, of these sizes will be
> - * available.
> - */
> -#define MAP_HUGE_512KB	(19 << MAP_HUGE_SHIFT)	/* 512KB HugeTLB Page */
> -#define MAP_HUGE_1MB	(20 << MAP_HUGE_SHIFT)	/* 1MB   HugeTLB Page */
> -#define MAP_HUGE_2MB	(21 << MAP_HUGE_SHIFT)	/* 2MB   HugeTLB Page */
> -#define MAP_HUGE_8MB	(23 << MAP_HUGE_SHIFT)	/* 8MB   HugeTLB Page */
> -#define MAP_HUGE_16MB	(24 << MAP_HUGE_SHIFT)	/* 16MB  HugeTLB Page */
> -#define MAP_HUGE_1GB	(30 << MAP_HUGE_SHIFT)	/* 1GB   HugeTLB Page */
> -#define MAP_HUGE_16GB	(34 << MAP_HUGE_SHIFT)	/* 16GB  HugeTLB Page */
> -
>  #endif /* _UAPI_ASM_POWERPC_MMAN_H */
> diff --git a/arch/x86/include/uapi/asm/mman.h b/arch/x86/include/uapi/asm/mman.h
> index 39bca7f..3be08f0 100644
> --- a/arch/x86/include/uapi/asm/mman.h
> +++ b/arch/x86/include/uapi/asm/mman.h
> @@ -3,9 +3,6 @@
>  
>  #define MAP_32BIT	0x40		/* only give out 32bit addresses */
>  
> -#define MAP_HUGE_2MB    (21 << MAP_HUGE_SHIFT)
> -#define MAP_HUGE_1GB    (30 << MAP_HUGE_SHIFT)
> -
>  #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
>  /*
>   * Take the 4 protection key bits out of the vma->vm_flags
> diff --git a/arch/xtensa/include/uapi/asm/mman.h b/arch/xtensa/include/uapi/asm/mman.h
> index 24365b3..8ce77a2 100644
> --- a/arch/xtensa/include/uapi/asm/mman.h
> +++ b/arch/xtensa/include/uapi/asm/mman.h
> @@ -106,17 +106,6 @@
>  /* compatibility flags */
>  #define MAP_FILE	0
>  
> -/*
> - * When MAP_HUGETLB is set bits [26:31] encode the log2 of the huge page size.
> - * This gives us 6 bits, which is enough until someone invents 128 bit address
> - * spaces.
> - *
> - * Assume these are all power of twos.
> - * When 0 use the default page size.
> - */
> -#define MAP_HUGE_SHIFT	26
> -#define MAP_HUGE_MASK	0x3f
> -
>  #define PKEY_DISABLE_ACCESS	0x1
>  #define PKEY_DISABLE_WRITE	0x2
>  #define PKEY_ACCESS_MASK	(PKEY_DISABLE_ACCESS |\
> diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h
> index 8c27db0..d248f3c 100644
> --- a/include/uapi/asm-generic/mman-common.h
> +++ b/include/uapi/asm-generic/mman-common.h
> @@ -61,17 +61,6 @@
>  /* compatibility flags */
>  #define MAP_FILE	0
>  
> -/*
> - * When MAP_HUGETLB is set bits [26:31] encode the log2 of the huge page size.
> - * This gives us 6 bits, which is enough until someone invents 128 bit address
> - * spaces.
> - *
> - * Assume these are all power of twos.
> - * When 0 use the default page size.
> - */
> -#define MAP_HUGE_SHIFT	26
> -#define MAP_HUGE_MASK	0x3f
> -
>  #define PKEY_DISABLE_ACCESS	0x1
>  #define PKEY_DISABLE_WRITE	0x2
>  #define PKEY_ACCESS_MASK	(PKEY_DISABLE_ACCESS |\
> diff --git a/include/uapi/linux/mman.h b/include/uapi/linux/mman.h
> index ade4acd..a937480 100644
> --- a/include/uapi/linux/mman.h
> +++ b/include/uapi/linux/mman.h
> @@ -2,6 +2,7 @@
>  #define _UAPI_LINUX_MMAN_H
>  
>  #include <asm/mman.h>
> +#include <asm-generic/hugetlb_encode.h>
>  
>  #define MREMAP_MAYMOVE	1
>  #define MREMAP_FIXED	2
> @@ -10,4 +11,25 @@
>  #define OVERCOMMIT_ALWAYS		1
>  #define OVERCOMMIT_NEVER		2
>  
> +/*
> + * Huge page size encoding when MAP_HUGETLB is specified, and a huge page
> + * size other than the default is desired.  See hugetlb_encode.h.
> + * All known huge page size encodings are provided here.  It is the
> + * responsibility of the application to know which sizes are supported on
> + * the running system.  See mmap(2) man page for details.
> + */
> +#define MAP_HUGE_SHIFT	HUGETLB_FLAG_ENCODE_SHIFT
> +#define MAP_HUGE_MASK	HUGETLB_FLAG_ENCODE_MASK
> +
> +#define MAP_HUGE_64KB	HUGETLB_FLAG_ENCODE_64KB
> +#define MAP_HUGE_512KB	HUGETLB_FLAG_ENCODE_512KB
> +#define MAP_HUGE_1MB	HUGETLB_FLAG_ENCODE_1MB
> +#define MAP_HUGE_2MB	HUGETLB_FLAG_ENCODE_2MB
> +#define MAP_HUGE_8MB	HUGETLB_FLAG_ENCODE_8MB
> +#define MAP_HUGE_16MB	HUGETLB_FLAG_ENCODE_16MB
> +#define MAP_HUGE_256MB	HUGETLB_FLAG_ENCODE_256MB
> +#define MAP_HUGE_1GB	HUGETLB_FLAG_ENCODE_1GB
> +#define MAP_HUGE_2GB	HUGETLB_FLAG_ENCODE_2GB
> +#define MAP_HUGE_16GB	HUGETLB_FLAG_ENCODE_16GB
> +
>  #endif /* _UAPI_LINUX_MMAN_H */
> -- 
> 2.7.5

-- 
Michal Hocko
SUSE Labs