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Commit 4e52780d authored by Eric B Munson's avatar Eric B Munson Committed by Linus Torvalds
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hugetlb: add MAP_HUGETLB for mmaping pseudo-anonymous huge page regions 



Add a flag for mmap that will be used to request a huge page region that
will look like anonymous memory to userspace.  This is accomplished by
using a file on the internal vfsmount.  MAP_HUGETLB is a modifier of
MAP_ANONYMOUS and so must be specified with it.  The region will behave
the same as a MAP_ANONYMOUS region using small pages.

[akpm@linux-foundation.org: fix arch definitions of MAP_HUGETLB]
Signed-off-by: default avatarEric B Munson <ebmunson@us.ibm.com>
Acked-by: default avatarDavid Rientjes <rientjes@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Adam Litke <agl@us.ibm.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 90f72aa5

include/linux/hugetlb.h

+7 −0
Original line number Diff line number Diff line
@@ -112,12 +112,19 @@ static inline void hugetlb_report_meminfo(struct seq_file *m) 


#endif /* !CONFIG_HUGETLB_PAGE */



#define HUGETLB_ANON_FILE "anon_hugepage"



enum {

	/*

	 * The file will be used as an shm file so shmfs accounting rules

	 * apply

	 */

	HUGETLB_SHMFS_INODE     = 1,

	/*

	 * The file is being created on the internal vfs mount and shmfs

	 * accounting rules do not apply

	 */

	HUGETLB_ANONHUGE_INODE  = 2,

};



#ifdef CONFIG_HUGETLBFS

mm/mmap.c

+18 −0
Original line number Diff line number Diff line
@@ -949,6 +949,24 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr, 
	if (mm->map_count > sysctl_max_map_count)

		return -ENOMEM;



	if (flags & MAP_HUGETLB) {

		struct user_struct *user = NULL;

		if (file)

			return -EINVAL;



		/*

		 * VM_NORESERVE is used because the reservations will be

		 * taken when vm_ops->mmap() is called

		 * A dummy user value is used because we are not locking

		 * memory so no accounting is necessary

		 */

		len = ALIGN(len, huge_page_size(&default_hstate));

		file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, VM_NORESERVE,

						&user, HUGETLB_ANONHUGE_INODE);

		if (IS_ERR(file))

			return PTR_ERR(file);

	}



	/* Obtain the address to map to. we verify (or select) it and ensure

	 * that it represents a valid section of the address space.

	 */