thp: consolidate code between handle_mm_fault() and do_huge_pmd_anonymous_page()

do_huge_pmd_anonymous_page() has copy-pasted piece of handle_mm_fault()
to handle fallback path.

Let's consolidate code back by introducing VM_FAULT_FALLBACK return
code.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Hillf Danton <dhillf@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Hugh Dickins <hughd@google.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 2 insertions, 4 deletions

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index b60de92e2edc..3935428c57cf 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -96,9 +96,6 @@ extern int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
                           pmd_t *dst_pmd, pmd_t *src_pmd,
                           struct vm_area_struct *vma,
                           unsigned long addr, unsigned long end);
-extern int handle_pte_fault(struct mm_struct *mm,
-                            struct vm_area_struct *vma, unsigned long address,
-                            pte_t *pte, pmd_t *pmd, unsigned int flags);
 extern int split_huge_page_to_list(struct page *page, struct list_head *list);
 static inline int split_huge_page(struct page *page)
 {
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 928df792c005..8b6e55ee8855 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -877,11 +877,12 @@ static inline int page_mapped(struct page *page)
 #define VM_FAULT_NOPAGE 0x0100  /* ->fault installed the pte, not return page */
 #define VM_FAULT_LOCKED 0x0200  /* ->fault locked the returned page */
 #define VM_FAULT_RETRY  0x0400  /* ->fault blocked, must retry */
+#define VM_FAULT_FALLBACK 0x0800        /* huge page fault failed, fall back to small */
 
 #define VM_FAULT_HWPOISON_LARGE_MASK 0xf000 /* encodes hpage index for large hwpoison */
 
 #define VM_FAULT_ERROR  (VM_FAULT_OOM | VM_FAULT_SIGBUS | VM_FAULT_HWPOISON | \
-                         VM_FAULT_HWPOISON_LARGE)
+                         VM_FAULT_FALLBACK | VM_FAULT_HWPOISON_LARGE)
 
 /* Encode hstate index for a hwpoisoned large page */
 #define VM_FAULT_SET_HINDEX(x) ((x) << 12)