[PATCH] hugetlb: demand fault handler

Below is a patch to implement demand faulting for huge pages.  The main
motivation for changing from prefaulting to demand faulting is so that huge
page memory areas can be allocated according to NUMA policy.

Thanks to consolidated hugetlb code, switching the behavior requires changing
only one fault handler.  The bulk of the patch just moves the logic from
hugelb_prefault() to hugetlb_pte_fault() and find_get_huge_page().

Signed-off-by: Adam Litke <agl@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 5 deletions

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 8f94feb24c0a..2627efe767cf 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -48,7 +48,6 @@ int sysctl_hugetlb_shm_group;
 static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
         struct inode *inode = file->f_dentry->d_inode;
-        struct address_space *mapping = inode->i_mapping;
         loff_t len, vma_len;
         int ret;
 
@@ -79,10 +78,8 @@ static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
         if (!(vma->vm_flags & VM_WRITE) && len > inode->i_size)
                 goto out;
 
-        ret = hugetlb_prefault(mapping, vma);
-        if (ret)
-                goto out;
-
+        ret = 0;
+        hugetlb_prefault_arch_hook(vma->vm_mm);
         if (inode->i_size < len)
                 inode->i_size = len;
 out: