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

Michal Hocko
2017-08-01T09:00:25Z

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@oracle.com>

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
> 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