[PATCH 0/3] Consolidate system call hugetlb page size encodings

[PATCH 0/3] Consolidate system call hugetlb page size encodings

[Mike Kravetz]

These patches are the result of discussions in this thread [1].  The
following changes are made in the patch set:

1) Put all the log2 encoded huge page size definitions in a common header
   file.  The idea is have a set of definitions that can be use as the
   basis for system call specific definitions such as MAP_HUGE_* and
   SHM_HUGE_*.
2) Remove MAP_HUGE_* definitions in arch specific files.  All these
   definitions are the same.  Consolidate all definitions in the primary
   user header file (uapi/linux/mman.h).
3) Remove SHM_HUGE_* definitions intended for user space from kernel
   header file, and add to user (uapi/linux/shm.h) header file.  Add
   definitions for all known huge page size encodings as in mmap.

[1]https://lkml.org/lkml/2017/3/8/548

Mike Kravetz (3):
  mm:hugetlb: Define system call hugetlb size encodings in single file
  mm: arch: Consolidate mmap hugetlb size encodings
  mm:shm: Use new hugetlb size encoding definitions

 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/linux/shm.h                       | 17 ----------------
 include/uapi/asm-generic/hugetlb_encode.h | 34 +++++++++++++++++++++++++++++++
 include/uapi/asm-generic/mman-common.h    | 11 ----------
 include/uapi/linux/mman.h                 | 22 ++++++++++++++++++++
 include/uapi/linux/shm.h                  | 31 ++++++++++++++++++++++++++--
 11 files changed, 85 insertions(+), 93 deletions(-)
 create mode 100644 include/uapi/asm-generic/hugetlb_encode.h

-- 
2.7.5

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[PATCH 1/3] mm:hugetlb: Define system call hugetlb size encodings in single file

[Mike Kravetz]

If hugetlb pages are requested in mmap or shmget system calls,  a huge
page size other than default can be requested.  This is accomplished by
encoding the log2 of the huge page size in the upper bits of the flag
argument.  asm-generic and arch specific headers all define the same
values for these encodings.

Put common definitions in a single header file.  The primary uapi
header files for mmap and shm will use these definitions as a basis
for definitions specific to those system calls.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
---
 include/uapi/asm-generic/hugetlb_encode.h | 34 +++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 include/uapi/asm-generic/hugetlb_encode.h

diff --git a/include/uapi/asm-generic/hugetlb_encode.h b/include/uapi/asm-generic/hugetlb_encode.h
new file mode 100644
index 0000000..e4732d3
--- /dev/null
+++ b/include/uapi/asm-generic/hugetlb_encode.h
@@ -0,0 +1,34 @@
+#ifndef _ASM_GENERIC_HUGETLB_ENCODE_H_
+#define _ASM_GENERIC_HUGETLB_ENCODE_H_
+
+/*
+ * Several system calls take a flag to request "hugetlb" huge pages.
+ * Without further specification, these system calls will use the
+ * system's default huge page size.  If a system supports multiple
+ * huge page sizes, the desired huge page size can be specified in
+ * bits [26:31] of the flag arguments.  The value in these 6 bits
+ * will encode the log2 of the huge page size.
+ *
+ * The following definitions are associated with this huge page size
+ * encoding in flag arguments.  System call specific header files
+ * that use this encoding should include this file.  They can then
+ * provide definitions based on these with their own specific prefix.
+ * for example:
+ * #define MAP_HUGE_SHIFT HUGETLB_FLAG_ENCODE_SHIFT
+ */
+
+#define HUGETLB_FLAG_ENCODE_SHIFT	26
+#define HUGETLB_FLAG_ENCODE_MASK	0x3f
+
+#define HUGETLB_FLAG_ENCODE_64KB	(16 << HUGETLB_FLAG_ENCODE_SHIFT)
+#define HUGETLB_FLAG_ENCODE_512KB	(19 << HUGETLB_FLAG_ENCODE_SHIFT)
+#define HUGETLB_FLAG_ENCODE_1MB		(20 << HUGETLB_FLAG_ENCODE_SHIFT)
+#define HUGETLB_FLAG_ENCODE_2MB		(21 << HUGETLB_FLAG_ENCODE_SHIFT)
+#define HUGETLB_FLAG_ENCODE_8MB		(23 << HUGETLB_FLAG_ENCODE_SHIFT)
+#define HUGETLB_FLAG_ENCODE_16MB	(24 << HUGETLB_FLAG_ENCODE_SHIFT)
+#define HUGETLB_FLAG_ENCODE_256MB	(28 << HUGETLB_FLAG_ENCODE_SHIFT)
+#define HUGETLB_FLAG_ENCODE_1GB		(30 << HUGETLB_FLAG_ENCODE_SHIFT)
+#define HUGETLB_FLAG_ENCODE_2GB		(31 << HUGETLB_FLAG_ENCODE_SHIFT)
+#define HUGETLB_FLAG_ENCODE_16GB	(34 << HUGETLB_FLAG_ENCODE_SHIFT)
+
+#endif /* _ASM_GENERIC_HUGETLB_ENCODE_H_ */
-- 
2.7.5

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Re: [PATCH 1/3] mm:hugetlb: Define system call hugetlb size encodings in single file

[Michal Hocko]

On Mon 31-07-17 11:56:24, Mike Kravetz wrote:
> If hugetlb pages are requested in mmap or shmget system calls,  a huge
> page size other than default can be requested.  This is accomplished by
> encoding the log2 of the huge page size in the upper bits of the flag
> argument.  asm-generic and arch specific headers all define the same
> values for these encodings.
> 
> Put common definitions in a single header file.  The primary uapi
> header files for mmap and shm will use these definitions as a basis
> for definitions specific to those system calls.
> 
> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>

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

> ---
>  include/uapi/asm-generic/hugetlb_encode.h | 34 +++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
>  create mode 100644 include/uapi/asm-generic/hugetlb_encode.h
> 
> diff --git a/include/uapi/asm-generic/hugetlb_encode.h b/include/uapi/asm-generic/hugetlb_encode.h
> new file mode 100644
> index 0000000..e4732d3
> --- /dev/null
> +++ b/include/uapi/asm-generic/hugetlb_encode.h
> @@ -0,0 +1,34 @@
> +#ifndef _ASM_GENERIC_HUGETLB_ENCODE_H_
> +#define _ASM_GENERIC_HUGETLB_ENCODE_H_
> +
> +/*
> + * Several system calls take a flag to request "hugetlb" huge pages.
> + * Without further specification, these system calls will use the
> + * system's default huge page size.  If a system supports multiple
> + * huge page sizes, the desired huge page size can be specified in
> + * bits [26:31] of the flag arguments.  The value in these 6 bits
> + * will encode the log2 of the huge page size.
> + *
> + * The following definitions are associated with this huge page size
> + * encoding in flag arguments.  System call specific header files
> + * that use this encoding should include this file.  They can then
> + * provide definitions based on these with their own specific prefix.
> + * for example:
> + * #define MAP_HUGE_SHIFT HUGETLB_FLAG_ENCODE_SHIFT
> + */
> +
> +#define HUGETLB_FLAG_ENCODE_SHIFT	26
> +#define HUGETLB_FLAG_ENCODE_MASK	0x3f
> +
> +#define HUGETLB_FLAG_ENCODE_64KB	(16 << HUGETLB_FLAG_ENCODE_SHIFT)
> +#define HUGETLB_FLAG_ENCODE_512KB	(19 << HUGETLB_FLAG_ENCODE_SHIFT)
> +#define HUGETLB_FLAG_ENCODE_1MB		(20 << HUGETLB_FLAG_ENCODE_SHIFT)
> +#define HUGETLB_FLAG_ENCODE_2MB		(21 << HUGETLB_FLAG_ENCODE_SHIFT)
> +#define HUGETLB_FLAG_ENCODE_8MB		(23 << HUGETLB_FLAG_ENCODE_SHIFT)
> +#define HUGETLB_FLAG_ENCODE_16MB	(24 << HUGETLB_FLAG_ENCODE_SHIFT)
> +#define HUGETLB_FLAG_ENCODE_256MB	(28 << HUGETLB_FLAG_ENCODE_SHIFT)
> +#define HUGETLB_FLAG_ENCODE_1GB		(30 << HUGETLB_FLAG_ENCODE_SHIFT)
> +#define HUGETLB_FLAG_ENCODE_2GB		(31 << HUGETLB_FLAG_ENCODE_SHIFT)
> +#define HUGETLB_FLAG_ENCODE_16GB	(34 << HUGETLB_FLAG_ENCODE_SHIFT)
> +
> +#endif /* _ASM_GENERIC_HUGETLB_ENCODE_H_ */
> -- 
> 2.7.5

-- 
Michal Hocko
SUSE Labs

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

[Mike Kravetz]

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>
---
 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

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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@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

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[PATCH 3/3] mm:shm: Use new hugetlb size encoding definitions

[Mike Kravetz]

Use the common definitions from hugetlb_encode.h header file for
encoding hugetlb size definitions in shmget system call flags.

In addition, move these definitions from the internal (kernel) to
user (uapi) header file.

Suggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
---
 include/linux/shm.h      | 17 -----------------
 include/uapi/linux/shm.h | 31 +++++++++++++++++++++++++++++--
 2 files changed, 29 insertions(+), 19 deletions(-)

diff --git a/include/linux/shm.h b/include/linux/shm.h
index 04e8818..d56285a 100644
--- a/include/linux/shm.h
+++ b/include/linux/shm.h
@@ -27,23 +27,6 @@ struct shmid_kernel /* private to the kernel */
 /* shm_mode upper byte flags */
 #define	SHM_DEST	01000	/* segment will be destroyed on last detach */
 #define SHM_LOCKED      02000   /* segment will not be swapped */
-#define SHM_HUGETLB     04000   /* segment will use huge TLB pages */
-#define SHM_NORESERVE   010000  /* don't check for reservations */
-
-/* Bits [26:31] are reserved */
-
-/*
- * When SHM_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 SHM_HUGE_SHIFT  26
-#define SHM_HUGE_MASK   0x3f
-#define SHM_HUGE_2MB    (21 << SHM_HUGE_SHIFT)
-#define SHM_HUGE_1GB    (30 << SHM_HUGE_SHIFT)
 
 #ifdef CONFIG_SYSVIPC
 struct sysv_shm {
diff --git a/include/uapi/linux/shm.h b/include/uapi/linux/shm.h
index 1fbf24e..cf23c87 100644
--- a/include/uapi/linux/shm.h
+++ b/include/uapi/linux/shm.h
@@ -3,6 +3,7 @@
 
 #include <linux/ipc.h>
 #include <linux/errno.h>
+#include <asm-generic/hugetlb_encode.h>
 #ifndef __KERNEL__
 #include <unistd.h>
 #endif
@@ -40,11 +41,37 @@ struct shmid_ds {
 /* Include the definition of shmid64_ds and shminfo64 */
 #include <asm/shmbuf.h>
 
-/* permission flag for shmget */
+/*
+ * shmget() shmflg values.
+ */
+/* The bottom nine bits are the same as open(2) mode flags */
 #define SHM_R		0400	/* or S_IRUGO from <linux/stat.h> */
 #define SHM_W		0200	/* or S_IWUGO from <linux/stat.h> */
+/* Bits 9 & 10 are IPC_CREAT and IPC_EXCL */
+#define SHM_HUGETLB	04000	/* segment will use huge TLB pages */
+#define SHM_NORESERVE	010000	/* don't check for reservations */
+
+/*
+ * Huge page size encoding when SHM_HUGETLB is specified, and a huge page
+ * size other than the default is desired.  See hugetlb_encode.h
+ */
+#define SHM_HUGE_SHIFT	HUGETLB_FLAG_ENCODE_SHIFT
+#define SHM_HUGE_MASK	HUGETLB_FLAG_ENCODE_MASK
+
+#define SHM_HUGE_64KB	HUGETLB_FLAG_ENCODE_64KB
+#define SHM_HUGE_512KB	HUGETLB_FLAG_ENCODE_512KB
+#define SHM_HUGE_1MB	HUGETLB_FLAG_ENCODE_1MB
+#define SHM_HUGE_2MB	HUGETLB_FLAG_ENCODE_2MB
+#define SHM_HUGE_8MB	HUGETLB_FLAG_ENCODE_8MB
+#define SHM_HUGE_16MB	HUGETLB_FLAG_ENCODE_16MB
+#define SHM_HUGE_256MB	HUGETLB_FLAG_ENCODE_256MB
+#define SHM_HUGE_1GB	HUGETLB_FLAG_ENCODE_1GB
+#define SHM_HUGE_2GB	HUGETLB_FLAG_ENCODE_2GB
+#define SHM_HUGE_16GB	HUGETLB_FLAG_ENCODE_16GB
 
-/* mode for attach */
+/*
+ * shmat() shmflg values
+ */
 #define	SHM_RDONLY	010000	/* read-only access */
 #define	SHM_RND		020000	/* round attach address to SHMLBA boundary */
 #define	SHM_REMAP	040000	/* take-over region on attach */
-- 
2.7.5

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Re: [PATCH 3/3] mm:shm: Use new hugetlb size encoding definitions

[Michal Hocko]

On Mon 31-07-17 11:56:26, Mike Kravetz wrote:
> Use the common definitions from hugetlb_encode.h header file for
> encoding hugetlb size definitions in shmget system call flags.
> 
> In addition, move these definitions from the internal (kernel) to
> user (uapi) header file.
> 
> Suggested-by: Matthew Wilcox <willy@infradead.org>
> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>

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

> ---
>  include/linux/shm.h      | 17 -----------------
>  include/uapi/linux/shm.h | 31 +++++++++++++++++++++++++++++--
>  2 files changed, 29 insertions(+), 19 deletions(-)
> 
> diff --git a/include/linux/shm.h b/include/linux/shm.h
> index 04e8818..d56285a 100644
> --- a/include/linux/shm.h
> +++ b/include/linux/shm.h
> @@ -27,23 +27,6 @@ struct shmid_kernel /* private to the kernel */
>  /* shm_mode upper byte flags */
>  #define	SHM_DEST	01000	/* segment will be destroyed on last detach */
>  #define SHM_LOCKED      02000   /* segment will not be swapped */
> -#define SHM_HUGETLB     04000   /* segment will use huge TLB pages */
> -#define SHM_NORESERVE   010000  /* don't check for reservations */
> -
> -/* Bits [26:31] are reserved */
> -
> -/*
> - * When SHM_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 SHM_HUGE_SHIFT  26
> -#define SHM_HUGE_MASK   0x3f
> -#define SHM_HUGE_2MB    (21 << SHM_HUGE_SHIFT)
> -#define SHM_HUGE_1GB    (30 << SHM_HUGE_SHIFT)
>  
>  #ifdef CONFIG_SYSVIPC
>  struct sysv_shm {
> diff --git a/include/uapi/linux/shm.h b/include/uapi/linux/shm.h
> index 1fbf24e..cf23c87 100644
> --- a/include/uapi/linux/shm.h
> +++ b/include/uapi/linux/shm.h
> @@ -3,6 +3,7 @@
>  
>  #include <linux/ipc.h>
>  #include <linux/errno.h>
> +#include <asm-generic/hugetlb_encode.h>
>  #ifndef __KERNEL__
>  #include <unistd.h>
>  #endif
> @@ -40,11 +41,37 @@ struct shmid_ds {
>  /* Include the definition of shmid64_ds and shminfo64 */
>  #include <asm/shmbuf.h>
>  
> -/* permission flag for shmget */
> +/*
> + * shmget() shmflg values.
> + */
> +/* The bottom nine bits are the same as open(2) mode flags */
>  #define SHM_R		0400	/* or S_IRUGO from <linux/stat.h> */
>  #define SHM_W		0200	/* or S_IWUGO from <linux/stat.h> */
> +/* Bits 9 & 10 are IPC_CREAT and IPC_EXCL */
> +#define SHM_HUGETLB	04000	/* segment will use huge TLB pages */
> +#define SHM_NORESERVE	010000	/* don't check for reservations */
> +
> +/*
> + * Huge page size encoding when SHM_HUGETLB is specified, and a huge page
> + * size other than the default is desired.  See hugetlb_encode.h
> + */
> +#define SHM_HUGE_SHIFT	HUGETLB_FLAG_ENCODE_SHIFT
> +#define SHM_HUGE_MASK	HUGETLB_FLAG_ENCODE_MASK
> +
> +#define SHM_HUGE_64KB	HUGETLB_FLAG_ENCODE_64KB
> +#define SHM_HUGE_512KB	HUGETLB_FLAG_ENCODE_512KB
> +#define SHM_HUGE_1MB	HUGETLB_FLAG_ENCODE_1MB
> +#define SHM_HUGE_2MB	HUGETLB_FLAG_ENCODE_2MB
> +#define SHM_HUGE_8MB	HUGETLB_FLAG_ENCODE_8MB
> +#define SHM_HUGE_16MB	HUGETLB_FLAG_ENCODE_16MB
> +#define SHM_HUGE_256MB	HUGETLB_FLAG_ENCODE_256MB
> +#define SHM_HUGE_1GB	HUGETLB_FLAG_ENCODE_1GB
> +#define SHM_HUGE_2GB	HUGETLB_FLAG_ENCODE_2GB
> +#define SHM_HUGE_16GB	HUGETLB_FLAG_ENCODE_16GB
>  
> -/* mode for attach */
> +/*
> + * shmat() shmflg values
> + */
>  #define	SHM_RDONLY	010000	/* read-only access */
>  #define	SHM_RND		020000	/* round attach address to SHMLBA boundary */
>  #define	SHM_REMAP	040000	/* take-over region on attach */
> -- 
> 2.7.5

-- 
Michal Hocko
SUSE Labs

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