mm: remove nopage

Nothing in the tree uses nopage any more.  Remove support for it in the
core mm code and documentation (and a few stray references to it in
comments).

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/feature-removal-schedule.txt

@@ -128,15 +128,6 @@ Who:	Arjan van de Ven <arjan@linux.intel.com>
 
 ---------------------------
 
-What:	vm_ops.nopage
-When:	Soon, provided in-kernel callers have been converted
-Why:	This interface is replaced by vm_ops.fault, but it has been around
-	forever, is used by a lot of drivers, and doesn't cost much to
-	maintain.
-Who:	Nick Piggin <npiggin@suse.de>
-
----------------------------
-
 What:	PHYSDEVPATH, PHYSDEVBUS, PHYSDEVDRIVER in the uevent environment
 When:	October 2008
 Why:	The stacking of class devices makes these values misleading and

Documentation/filesystems/Locking

@@ -511,15 +511,13 @@ prototypes:
 	void (*open)(struct vm_area_struct*);
 	void (*close)(struct vm_area_struct*);
 	int (*fault)(struct vm_area_struct*, struct vm_fault *);
-	struct page *(*nopage)(struct vm_area_struct*, unsigned long, int *);
 	int (*page_mkwrite)(struct vm_area_struct *, struct page *);
 
 locking rules:
 		BKL	mmap_sem	PageLocked(page)
 open:		no	yes
 close:		no	yes
 fault:		no	yes
-nopage:		no	yes
 page_mkwrite:	no	yes		no
 
 	->page_mkwrite() is called when a previously read-only page is
@@ -537,4 +535,3 @@ NULL.
 
 ipc/shm.c::shm_delete() - may need BKL.
 ->read() and ->write() in many drivers are (probably) missing BKL.
-drivers/sgi/char/graphics.c::sgi_graphics_nopage() - may need BKL.

drivers/media/video/vino.c

@@ -13,7 +13,7 @@
 /*
  * TODO:
  * - remove "mark pages reserved-hacks" from memory allocation code
- *   and implement nopage()
+ *   and implement fault()
  * - check decimation, calculating and reporting image size when
  *   using decimation
  * - implement read(), user mode buffers and overlay (?)

drivers/video/vermilion/vermilion.c

@@ -112,8 +112,9 @@ static int vmlfb_alloc_vram_area(struct vram_area *va, unsigned max_order,
 
 	/*
 	 * It seems like __get_free_pages only ups the usage count
-	 * of the first page. This doesn't work with nopage mapping, so
-	 * up the usage count once more.
+	 * of the first page. This doesn't work with fault mapping, so
+	 * up the usage count once more (XXX: should use split_page or
+	 * compound page).
 	 */
 
 	memset((void *)va->logical, 0x00, va->size);

fs/gfs2/ops_address.c

@@ -438,7 +438,7 @@ static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
 	int error;
 
 	/*
-	 * Due to the order of unstuffing files and ->nopage(), we can be
+	 * Due to the order of unstuffing files and ->fault(), we can be
 	 * asked for a zero page in the case of a stuffed file being extended,
 	 * so we need to supply one here. It doesn't happen often.
 	 */

include/linux/mm.h

@@ -164,8 +164,6 @@ struct vm_operations_struct {
 	void (*open)(struct vm_area_struct * area);
 	void (*close)(struct vm_area_struct * area);
 	int (*fault)(struct vm_area_struct *vma, struct vm_fault *vmf);
-	struct page *(*nopage)(struct vm_area_struct *area,
-			unsigned long address, int *type);
 	unsigned long (*nopfn)(struct vm_area_struct *area,
 			unsigned long address);
 
@@ -648,12 +646,6 @@ static inline int page_mapped(struct page *page)
 	return atomic_read(&(page)->_mapcount) >= 0;
 }
 
-/*
- * Error return values for the *_nopage functions
- */
-#define NOPAGE_SIGBUS	(NULL)
-#define NOPAGE_OOM	((struct page *) (-1))
-
 /*
  * Error return values for the *_nopfn functions
  */

mm/memory.c

@@ -1057,8 +1057,7 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 		if (pages)
 			foll_flags |= FOLL_GET;
 		if (!write && !(vma->vm_flags & VM_LOCKED) &&
-		    (!vma->vm_ops || (!vma->vm_ops->nopage &&
-					!vma->vm_ops->fault)))
+		    (!vma->vm_ops || !vma->vm_ops->fault))
 			foll_flags |= FOLL_ANON;
 
 		do {
@@ -2199,20 +2198,9 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 
 	BUG_ON(vma->vm_flags & VM_PFNMAP);
 
-	if (likely(vma->vm_ops->fault)) {
-		ret = vma->vm_ops->fault(vma, &vmf);
-		if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
-			return ret;
-	} else {
-		/* Legacy ->nopage path */
-		ret = 0;
-		vmf.page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
-		/* no page was available -- either SIGBUS or OOM */
-		if (unlikely(vmf.page == NOPAGE_SIGBUS))
-			return VM_FAULT_SIGBUS;
-		else if (unlikely(vmf.page == NOPAGE_OOM))
-			return VM_FAULT_OOM;
-	}
+	ret = vma->vm_ops->fault(vma, &vmf);
+	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
+		return ret;
 
 	/*
 	 * For consistency in subsequent calls, make the faulted page always
@@ -2458,7 +2446,7 @@ static inline int handle_pte_fault(struct mm_struct *mm,
 	if (!pte_present(entry)) {
 		if (pte_none(entry)) {
 			if (vma->vm_ops) {
-				if (vma->vm_ops->fault || vma->vm_ops->nopage)
+				if (likely(vma->vm_ops->fault))
 					return do_linear_fault(mm, vma, address,
 						pte, pmd, write_access, entry);
 				if (unlikely(vma->vm_ops->nopfn))

mm/mincore.c

@@ -33,7 +33,7 @@ static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)
 	 * When tmpfs swaps out a page from a file, any process mapping that
 	 * file will not get a swp_entry_t in its pte, but rather it is like
 	 * any other file mapping (ie. marked !present and faulted in with
-	 * tmpfs's .nopage). So swapped out tmpfs mappings are tested here.
+	 * tmpfs's .fault). So swapped out tmpfs mappings are tested here.
 	 *
 	 * However when tmpfs moves the page from pagecache and into swapcache,
 	 * it is still in core, but the find_get_page below won't find it.

mm/rmap.c

@@ -662,7 +662,6 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma)
 			printk (KERN_EMERG "  page->mapping = %p\n", page->mapping);
 			print_symbol (KERN_EMERG "  vma->vm_ops = %s\n", (unsigned long)vma->vm_ops);
 			if (vma->vm_ops) {
-				print_symbol (KERN_EMERG "  vma->vm_ops->nopage = %s\n", (unsigned long)vma->vm_ops->nopage);
 				print_symbol (KERN_EMERG "  vma->vm_ops->fault = %s\n", (unsigned long)vma->vm_ops->fault);
 			}
 			if (vma->vm_file && vma->vm_file->f_op)