Add pseudo-anonymous huge page mappings V4

This patch set adds a flag to mmap that allows the user to request a mapping to be backed with huge pages. This mapping will borrow functionality from the huge page shm code to create a file on the kernel internal mount and use it to approximate an anonymous mapping. The MAP_HUGETLB flag is a modifier to MAP_ANONYMOUS and will not work without both flags being preset.

A new flag is necessary because there is no other way to hook into huge pages without creating a file on a hugetlbfs mount which wouldn't be MAP_ANONYMOUS.

To userspace, this mapping will behave just like an anonymous mapping because the file is not accessible outside of the kernel.

This patch set is meant to simplify the programming model, presently there is a large chunk of boiler plate code, contained in libhugetlbfs, required to create private, hugepage backed mappings. This patch set would allow use of hugepages without linking to libhugetlbfs or having hugetblfs mounted.

Unification of the VM code would provide these same benefits, but it has been resisted each time that it has been suggested for several
reasons: it would break PAGE_SIZE assumptions across the kernel, it makes page-table abstractions really expensive, and it does not provide any benefit on architectures that do not support huge pages, incurring fast path penalties without providing any benefit on these architectures.

Eric B Munson (3):
hugetlbfs: Allow the creation of files suitable for MAP_PRIVATE on
the vfs internal mount
Add MAP_HUGETLB for mmaping pseudo-anonymous huge page regions Add MAP_HUGETLB example

 Documentation/vm/00-INDEX         |    2 +
 Documentation/vm/hugetlbpage.txt  |   14 ++++---
 Documentation/vm/map_hugetlb.c    |   77 +++++++++++++++++++++++++++++++++++++
 fs/hugetlbfs/inode.c              |   21 ++++++++--
 include/asm-generic/mman-common.h |    1 +
 include/linux/hugetlb.h           |   19 ++++++++-
 ipc/shm.c                         |    2 +-
 mm/mmap.c                         |   19 +++++++++
 8 files changed, 142 insertions(+), 13 deletions(-)
 create mode 100644 Documentation/vm/map_hugetlb.c

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