Zhang, Yanmin b6174df5ee [PATCH] mmap zero-length hugetlb file with PROT_NONE to protect a hugetlb virtual area ... Sometimes, applications need below call to be successful although "/mnt/hugepages/file1" doesn't exist. fd = open("/mnt/hugepages/file1", O_CREAT|O_RDWR, 0755); *addr = mmap(NULL, 0x1024*1024*256, PROT_NONE, 0, fd, 0); As for regular pages (or files), above call does work, but as for huge pages, above call would fail because hugetlbfs_file_mmap would fail if (!(vma->vm_flags & VM_WRITE) && len > inode->i_size). This capability on huge page is useful on ia64 when the process wants to protect one area on region 4, so other threads couldn't read/write this area. A famous JVM (Java Virtual Machine) implementation on IA64 needs the capability. Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hugh@veritas.com> [ Expand-on-mmap semantics again... this time matching normal fs's. wli ] Acked-by: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>		2006-07-10 13:24:21 -07:00
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inode.c	[PATCH] mmap zero-length hugetlb file with PROT_NONE to protect a hugetlb virtual area	2006-07-10 13:24:21 -07:00
Makefile	Linux-2.6.12-rc2	2005-04-16 15:20:36 -07:00