mm: Change return type int to vm_fault_t for fault handlers

Use new return type vm_fault_t for fault handler.  For now, this is just
documenting that the function returns a VM_FAULT value rather than an
errno.  Once all instances are converted, vm_fault_t will become a
distinct type.

Ref-> commit 1c8f422059ae ("mm: change return type to vm_fault_t")

The aim is to change the return type of finish_fault() and
handle_mm_fault() to vm_fault_t type.  As part of that clean up return
type of all other recursively called functions have been changed to
vm_fault_t type.

The places from where handle_mm_fault() is getting invoked will be
change to vm_fault_t type but in a separate patch.

vmf_error() is the newly introduce inline function in 4.17-rc6.

[akpm@linux-foundation.org: don't shadow outer local `ret' in __do_huge_pmd_anonymous_page()]
Link: http://lkml.kernel.org/r/20180604171727.GA20279@jordon-HP-15-Notebook-PC
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 13 insertions, 16 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 9f1c853f67b5..3c21775f196b 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3501,14 +3501,15 @@ static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
  * cannot race with other handlers or page migration.
  * Keep the pte_same checks anyway to make transition from the mutex easier.
  */
-static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
+static vm_fault_t hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
 		       unsigned long address, pte_t *ptep,
 		       struct page *pagecache_page, spinlock_t *ptl)
 {
 	pte_t pte;
 	struct hstate *h = hstate_vma(vma);
 	struct page *old_page, *new_page;
-	int ret = 0, outside_reserve = 0;
+	int outside_reserve = 0;
+	vm_fault_t ret = 0;
 	unsigned long mmun_start;	/* For mmu_notifiers */
 	unsigned long mmun_end;		/* For mmu_notifiers */
 	unsigned long haddr = address & huge_page_mask(h);
@@ -3572,8 +3573,7 @@ retry_avoidcopy:
 			return 0;
 		}
 
-		ret = (PTR_ERR(new_page) == -ENOMEM) ?
-			VM_FAULT_OOM : VM_FAULT_SIGBUS;
+		ret = vmf_error(PTR_ERR(new_page));
 		goto out_release_old;
 	}
 
@@ -3676,12 +3676,13 @@ int huge_add_to_page_cache(struct page *page, struct address_space *mapping,
 	return 0;
 }
 
-static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
-			   struct address_space *mapping, pgoff_t idx,
-			   unsigned long address, pte_t *ptep, unsigned int flags)
+static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
+			struct vm_area_struct *vma,
+			struct address_space *mapping, pgoff_t idx,
+			unsigned long address, pte_t *ptep, unsigned int flags)
 {
 	struct hstate *h = hstate_vma(vma);
-	int ret = VM_FAULT_SIGBUS;
+	vm_fault_t ret = VM_FAULT_SIGBUS;
 	int anon_rmap = 0;
 	unsigned long size;
 	struct page *page;
@@ -3744,11 +3745,7 @@ retry:
 
 		page = alloc_huge_page(vma, haddr, 0);
 		if (IS_ERR(page)) {
-			ret = PTR_ERR(page);
-			if (ret == -ENOMEM)
-				ret = VM_FAULT_OOM;
-			else
-				ret = VM_FAULT_SIGBUS;
+			ret = vmf_error(PTR_ERR(page));
 			goto out;
 		}
 		clear_huge_page(page, address, pages_per_huge_page(h));
@@ -3872,12 +3869,12 @@ u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
 }
 #endif
 
-int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
+vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 			unsigned long address, unsigned int flags)
 {
 	pte_t *ptep, entry;
 	spinlock_t *ptl;
-	int ret;
+	vm_fault_t ret;
 	u32 hash;
 	pgoff_t idx;
 	struct page *page = NULL;
@@ -4207,7 +4204,7 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
 		if (absent || is_swap_pte(huge_ptep_get(pte)) ||
 		    ((flags & FOLL_WRITE) &&
 		      !huge_pte_write(huge_ptep_get(pte)))) {
-			int ret;
+			vm_fault_t ret;
 			unsigned int fault_flags = 0;
 
 			if (pte)