mm: add a pmd_fault handler

Allow non-anonymous VMAs to provide huge pages in response to a page fault.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/mm.h b/include/linux/mm.h
index dfb7ce0..e1fbd18 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -249,6 +249,8 @@ struct vm_operations_struct {
        void (*close)(struct vm_area_struct * area);
        int (*mremap)(struct vm_area_struct * area);
        int (*fault)(struct vm_area_struct *vma, struct vm_fault *vmf);
+       int (*pmd_fault)(struct vm_area_struct *, unsigned long address,
+                                               pmd_t *, unsigned int flags);
        void (*map_pages)(struct vm_area_struct *vma, struct vm_fault *vmf);
 
        /* notification that a previously read-only page is about to become

diff --git a/mm/memory.c b/mm/memory.c
index 882c9d7..a3f9a8c 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3232,6 +3232,27 @@ out:
        return 0;
 }
 
+static int create_huge_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
+                       unsigned long address, pmd_t *pmd, unsigned int flags)
+{
+       if (!vma->vm_ops)
+               return do_huge_pmd_anonymous_page(mm, vma, address, pmd, flags);
+       if (vma->vm_ops->pmd_fault)
+               return vma->vm_ops->pmd_fault(vma, address, pmd, flags);
+       return VM_FAULT_FALLBACK;
+}
+
+static int wp_huge_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
+                       unsigned long address, pmd_t *pmd, pmd_t orig_pmd,
+                       unsigned int flags)
+{
+       if (!vma->vm_ops)
+               return do_huge_pmd_wp_page(mm, vma, address, pmd, orig_pmd);
+       if (vma->vm_ops->pmd_fault)
+               return vma->vm_ops->pmd_fault(vma, address, pmd, flags);
+       return VM_FAULT_FALLBACK;
+}
+
 /*
  * These routines also need to handle stuff like marking pages dirty
  * and/or accessed for architectures that don't do it in hardware (most
@@ -3334,10 +3355,7 @@ static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
        if (!pmd)
                return VM_FAULT_OOM;
        if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
-               int ret = VM_FAULT_FALLBACK;
-               if (!vma->vm_ops)
-                       ret = do_huge_pmd_anonymous_page(mm, vma, address,
-                                       pmd, flags);
+               int ret = create_huge_pmd(mm, vma, address, pmd, flags);
                if (!(ret & VM_FAULT_FALLBACK))
                        return ret;
        } else {
@@ -3361,8 +3379,8 @@ static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
                                                             orig_pmd, pmd);
 
                        if (dirty && !pmd_write(orig_pmd)) {
-                               ret = do_huge_pmd_wp_page(mm, vma, address, pmd,
-                                                         orig_pmd);
+                               ret = wp_huge_pmd(mm, vma, address, pmd,
+                                                       orig_pmd, flags);
                                if (!(ret & VM_FAULT_FALLBACK))
                                        return ret;
                        } else {