[patch 3/3] mm: remove nopage

[Nick Piggin]

Patch against 2.6.24-rc6-mm1... nothing in your tree appears to use nopage.
This patch should transfer without rejects upstream, so it shouldn't be too
difficult.

Would be nice to get in 2.6.25 if we can.

---

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@xxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 Documentation/feature-removal-schedule.txt |    9 --------
 Documentation/filesystems/Locking          |    3 --
 drivers/media/video/vino.c                 |    2 -
 drivers/video/vermilion/vermilion.c        |    5 ++--
 include/linux/mm.h                         |    8 -------
 mm/memory.c                                |   32 ++++++++++-------------------
 mm/mincore.c                               |    2 -
 mm/mmap.c                                  |   20 +++++++++---------
 mm/rmap.c                                  |    1 
 9 files changed, 27 insertions(+), 55 deletions(-)

Index: linux-2.6/include/linux/mm.h
===================================================================
--- linux-2.6.orig/include/linux/mm.h
+++ linux-2.6/include/linux/mm.h
@@ -166,8 +166,6 @@ 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);
 
@@ -642,12 +640,6 @@ static inline int page_mapped(struct pag
 }
 
 /*
- * Error return values for the *_nopage functions
- */
-#define NOPAGE_SIGBUS	(NULL)
-#define NOPAGE_OOM	((struct page *) (-1))
-
-/*
  * Error return values for the *_nopfn functions
  */
 #define NOPFN_SIGBUS	((unsigned long) -1)
Index: linux-2.6/mm/memory.c
===================================================================
--- linux-2.6.orig/mm/memory.c
+++ linux-2.6/mm/memory.c
@@ -1042,8 +1042,7 @@ int get_user_pages(struct task_struct *t
 		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 {
@@ -2184,20 +2183,9 @@ static int __do_fault(struct mm_struct *
 
 	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
@@ -2443,7 +2431,7 @@ static inline int handle_pte_fault(struc
 	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))
Index: linux-2.6/mm/mincore.c
===================================================================
--- linux-2.6.orig/mm/mincore.c
+++ linux-2.6/mm/mincore.c
@@ -33,7 +33,7 @@ static unsigned char mincore_page(struct
 	 * 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.
Index: linux-2.6/Documentation/feature-removal-schedule.txt
===================================================================
--- linux-2.6.orig/Documentation/feature-removal-schedule.txt
+++ linux-2.6/Documentation/feature-removal-schedule.txt
@@ -155,15 +155,6 @@ Who:	Greg Kroah-Hartman <gregkh@xxxxxxx>
 
 ---------------------------
 
-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@xxxxxxx>
-
----------------------------
-
 What:	PHYSDEVPATH, PHYSDEVBUS, PHYSDEVDRIVER in the uevent environment
 When:	October 2008
 Why:	The stacking of class devices makes these values misleading and
Index: linux-2.6/Documentation/filesystems/Locking
===================================================================
--- linux-2.6.orig/Documentation/filesystems/Locking
+++ linux-2.6/Documentation/filesystems/Locking
@@ -511,7 +511,6 @@ 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:
@@ -519,7 +518,6 @@ locking rules:
 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.
Index: linux-2.6/mm/rmap.c
===================================================================
--- linux-2.6.orig/mm/rmap.c
+++ linux-2.6/mm/rmap.c
@@ -655,7 +655,6 @@ void page_remove_rmap(struct page *page,
 			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)
Index: linux-2.6/drivers/media/video/vino.c
===================================================================
--- linux-2.6.orig/drivers/media/video/vino.c
+++ linux-2.6/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 (?)
Index: linux-2.6/drivers/video/vermilion/vermilion.c
===================================================================
--- linux-2.6.orig/drivers/video/vermilion/vermilion.c
+++ linux-2.6/drivers/video/vermilion/vermilion.c
@@ -114,8 +114,9 @@ static int vmlfb_alloc_vram_area(struct 
 
 	/*
 	 * 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);
Index: linux-2.6/fs/gfs2/ops_address.c
===================================================================
--- linux-2.6.orig/fs/gfs2/ops_address.c
+++ linux-2.6/fs/gfs2/ops_address.c
@@ -441,7 +441,7 @@ static int stuffed_readpage(struct gfs2_
 	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.
 	 */
--
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