hugetlb: add MAP_HUGETLB for mmaping pseudo-anonymous huge page regions (4e52780d) · Commits · 戴 / test

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:

Eric B Munson <ebmunson@us.ibm.com> Acked-by:

David 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:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

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.
		*/

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