Re: [patch 3/8] mm: merge nopfn into fault

[Nick Piggin <npiggin@suse.de>]

On Wed, May 23, 2007 at 08:37:28PM -0700, Linus Torvalds wrote:
> 
> So just about any "hiding" would do it as far as I'm concerned. Ranging 
> from the odd (making it a "virtual page number") to just using an 
> inconvenient name that just makes it obvious that it shouldn't be used 
> lightly ("virtual_page_fault_address"), to making it a type that cannot 
> easily be used for that kind of arithmetic ("void __user *" would make 
> sense, no?).

OK, attached is an incremental diff (against patch 2 in the series)
that changes the API around and feels a bit cleaner.

What do you think? Any better?

---

Change ->fault prototype. We now return an int, which contains VM_FAULT_xxx
code in the low byte, and FAULT_RET_xxx code in the next byte. FAULT_RET_ code
tells the VM whether a page was found, whether it has been locked, and
potentially other things.

This means we no longer set VM_CAN_INVALIDATE in the vma in order to say
that a page is locked. This requires filemap_nopage to go away, so let's
just nuke all that stuff now instead of doing a seperate patch for it at the
end.

struct fault_data is renamed to struct vm_fault as Linus asked. address
is now a void __user * that we should firmly encourage drivers not to use.

The page is now returned via a page pointer in the vm_fault struct.

---
 Documentation/feature-removal-schedule.txt |   20 --
 fs/gfs2/ops_file.c                         |    2 
 fs/gfs2/ops_vm.c                           |   47 ++--
 fs/ncpfs/mmap.c                            |   35 +--
 fs/ocfs2/mmap.c                            |   27 +-
 fs/xfs/linux-2.6/xfs_file.c                |   12 -
 include/linux/mm.h                         |   82 ++++----
 ipc/shm.c                                  |    5 
 mm/filemap.c                               |  283 ++++-------------------------
 mm/filemap_xip.c                           |   37 +--
 mm/memory.c                                |   97 ++++-----
 mm/nommu.c                                 |    2 
 mm/shmem.c                                 |   29 +-
 13 files changed, 214 insertions(+), 464 deletions(-)

Index: linux-2.6/fs/gfs2/ops_vm.c
===================================================================
--- linux-2.6.orig/fs/gfs2/ops_vm.c
+++ linux-2.6/fs/gfs2/ops_vm.c
@@ -27,13 +27,12 @@
 #include "trans.h"
 #include "util.h"
 
-static struct page *gfs2_private_fault(struct vm_area_struct *vma,
-					struct fault_data *fdata)
+static int gfs2_private_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	struct gfs2_inode *ip = GFS2_I(vma->vm_file->f_mapping->host);
 
 	set_bit(GIF_PAGED, &ip->i_flags);
-	return filemap_fault(vma, fdata);
+	return filemap_fault(vma, vmf);
 }
 
 static int alloc_page_backing(struct gfs2_inode *ip, struct page *page)
@@ -104,55 +103,55 @@ out:
 	return error;
 }
 
-static struct page *gfs2_sharewrite_fault(struct vm_area_struct *vma,
-						struct fault_data *fdata)
+static int gfs2_sharewrite_fault(struct vm_area_struct *vma,
+						struct vm_fault *vmf)
 {
 	struct file *file = vma->vm_file;
 	struct gfs2_file *gf = file->private_data;
 	struct gfs2_inode *ip = GFS2_I(file->f_mapping->host);
 	struct gfs2_holder i_gh;
-	struct page *result = NULL;
 	int alloc_required;
 	int error;
+	int ret = VM_FAULT_MINOR;
 
 	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &i_gh);
 	if (error)
-		return NULL;
+		goto out;
 
 	set_bit(GIF_PAGED, &ip->i_flags);
 	set_bit(GIF_SW_PAGED, &ip->i_flags);
 
 	error = gfs2_write_alloc_required(ip,
-					(u64)fdata->pgoff << PAGE_CACHE_SHIFT,
+					(u64)vmf->pgoff << PAGE_CACHE_SHIFT,
 					PAGE_CACHE_SIZE, &alloc_required);
 	if (error) {
-		fdata->type = VM_FAULT_OOM; /* XXX: are these right? */
-		goto out;
+		ret = VM_FAULT_OOM; /* XXX: are these right? */
+		goto out_unlock;
 	}
 
 	set_bit(GFF_EXLOCK, &gf->f_flags);
-	result = filemap_fault(vma, fdata);
+	ret = filemap_fault(vma, vmf);
 	clear_bit(GFF_EXLOCK, &gf->f_flags);
-	if (!result)
-		goto out;
+	if (ret & (VM_FAULT_ERROR | FAULT_RET_NOPAGE))
+		goto out_unlock;
 
 	if (alloc_required) {
-		error = alloc_page_backing(ip, result);
+		/* XXX: do we need to drop page lock around alloc_page_backing?*/
+		error = alloc_page_backing(ip, vmf->page);
 		if (error) {
-			if (vma->vm_flags & VM_CAN_INVALIDATE)
-				unlock_page(result);
-			page_cache_release(result);
-			fdata->type = VM_FAULT_OOM;
-			result = NULL;
-			goto out;
+			if (ret & FAULT_RET_LOCKED)
+				unlock_page(vmf->page);
+			page_cache_release(vmf->page);
+			ret = VM_FAULT_OOM;
+			goto out_unlock;
 		}
-		set_page_dirty(result);
+		set_page_dirty(vmf->page);
 	}
 
-out:
+out_unlock:
 	gfs2_glock_dq_uninit(&i_gh);
-
-	return result;
+out:
+	return ret;
 }
 
 struct vm_operations_struct gfs2_vm_ops_private = {
Index: linux-2.6/fs/ncpfs/mmap.c
===================================================================
--- linux-2.6.orig/fs/ncpfs/mmap.c
+++ linux-2.6/fs/ncpfs/mmap.c
@@ -24,33 +24,35 @@
 
 /*
  * Fill in the supplied page for mmap
+ * XXX: how are we excluding truncate/invalidate here? Maybe need to lock
+ * page?
  */
-static struct page* ncp_file_mmap_fault(struct vm_area_struct *area,
-						struct fault_data *fdata)
+static int ncp_file_mmap_fault(struct vm_area_struct *area,
+					struct vm_fault *vmf)
 {
 	struct file *file = area->vm_file;
 	struct dentry *dentry = file->f_path.dentry;
 	struct inode *inode = dentry->d_inode;
-	struct page* page;
 	char *pg_addr;
 	unsigned int already_read;
 	unsigned int count;
 	int bufsize;
-	int pos;
+	int pos; /* XXX: loff_t ? */
 
-	page = alloc_page(GFP_HIGHUSER); /* ncpfs has nothing against high pages
-	           as long as recvmsg and memset works on it */
-	if (!page) {
-		fdata->type = VM_FAULT_OOM;
-		return NULL;
-	}
-	pg_addr = kmap(page);
-	pos = fdata->pgoff << PAGE_SHIFT;
+	/*
+	 * ncpfs has nothing against high pages as long
+	 * as recvmsg and memset works on it
+	 */
+	vmf->page = alloc_page(GFP_HIGHUSER);
+	if (!page)
+		return VM_FAULT_OOM;
+	pg_addr = kmap(vmf->page);
+	pos = vmf->pgoff << PAGE_SHIFT;
 
 	count = PAGE_SIZE;
-	if (fdata->address + PAGE_SIZE > area->vm_end) {
+	if (vmf->virtual_address + PAGE_SIZE > area->vm_end) {
 		WARN_ON(1); /* shouldn't happen? */
-		count = area->vm_end - fdata->address;
+		count = area->vm_end - vmf->virtual_address;
 	}
 	/* what we can read in one go */
 	bufsize = NCP_SERVER(inode)->buffer_size;
@@ -85,17 +87,16 @@ static struct page* ncp_file_mmap_fault(
 
 	if (already_read < PAGE_SIZE)
 		memset(pg_addr + already_read, 0, PAGE_SIZE - already_read);
-	flush_dcache_page(page);
-	kunmap(page);
+	flush_dcache_page(vmf->page);
+	kunmap(vmf->page);
 
 	/*
 	 * If I understand ncp_read_kernel() properly, the above always
 	 * fetches from the network, here the analogue of disk.
 	 * -- wli
 	 */
-	fdata->type = VM_FAULT_MAJOR;
 	count_vm_event(PGMAJFAULT);
-	return page;
+	return VM_FAULT_MAJOR;
 }
 
 static struct vm_operations_struct ncp_file_mmap =
Index: linux-2.6/fs/ocfs2/mmap.c
===================================================================
--- linux-2.6.orig/fs/ocfs2/mmap.c
+++ linux-2.6/fs/ocfs2/mmap.c
@@ -42,14 +42,13 @@
 #include "inode.h"
 #include "mmap.h"
 
-static struct page *ocfs2_fault(struct vm_area_struct *area,
-						struct fault_data *fdata)
+static int ocfs2_fault(struct vm_area_struct *area, struct vm_fault *vmf)
 {
 	struct page *page = NULL;
 	sigset_t blocked, oldset;
-	int ret;
+	int error, ret;
 
-	mlog_entry("(area=%p, page offset=%lu)\n", area, fdata->pgoff);
+	mlog_entry("(area=%p, page offset=%lu)\n", area, vmf->pgoff);
 
 	/* The best way to deal with signals in this path is
 	 * to block them upfront, rather than allowing the
@@ -58,21 +57,21 @@ static struct page *ocfs2_fault(struct v
 
 	/* We should technically never get a bad ret return
 	 * from sigprocmask */
-	ret = sigprocmask(SIG_BLOCK, &blocked, &oldset);
-	if (ret < 0) {
-		fdata->type = VM_FAULT_SIGBUS;
-		mlog_errno(ret);
+	error = sigprocmask(SIG_BLOCK, &blocked, &oldset);
+	if (error < 0) {
+		mlog_errno(error);
+		ret = VM_FAULT_SIGBUS;
 		goto out;
 	}
 
-	page = filemap_fault(area, fdata);
+	ret = filemap_fault(area, vmf);
 
-	ret = sigprocmask(SIG_SETMASK, &oldset, NULL);
-	if (ret < 0)
-		mlog_errno(ret);
+	error = sigprocmask(SIG_SETMASK, &oldset, NULL);
+	if (error < 0)
+		mlog_errno(error);
 out:
-	mlog_exit_ptr(page);
-	return page;
+	mlog_exit_ptr(vmf->page);
+	return ret;
 }
 
 static struct vm_operations_struct ocfs2_file_vm_ops = {
Index: linux-2.6/fs/xfs/linux-2.6/xfs_file.c
===================================================================
--- linux-2.6.orig/fs/xfs/linux-2.6/xfs_file.c
+++ linux-2.6/fs/xfs/linux-2.6/xfs_file.c
@@ -245,20 +245,18 @@ xfs_file_fsync(
 }
 
 #ifdef CONFIG_XFS_DMAPI
-STATIC struct page *
+STATIC int
 xfs_vm_fault(
 	struct vm_area_struct	*vma,
-	struct fault_data	*fdata)
+	struct vm_fault	*vmf)
 {
 	struct inode	*inode = vma->vm_file->f_path.dentry->d_inode;
 	bhv_vnode_t	*vp = vn_from_inode(inode);
 
 	ASSERT_ALWAYS(vp->v_vfsp->vfs_flag & VFS_DMI);
-	if (XFS_SEND_MMAP(XFS_VFSTOM(vp->v_vfsp), vma, 0)) {
-		fdata->type = VM_FAULT_SIGBUS;
-		return NULL;
-	}
-	return filemap_fault(vma, fdata);
+	if (XFS_SEND_MMAP(XFS_VFSTOM(vp->v_vfsp), vma, 0))
+		return VM_FAULT_SIGBUS;
+	return filemap_fault(vma, vmf);
 }
 #endif /* CONFIG_XFS_DMAPI */
 
Index: linux-2.6/include/linux/mm.h
===================================================================
--- linux-2.6.orig/include/linux/mm.h
+++ linux-2.6/include/linux/mm.h
@@ -170,12 +170,7 @@ extern unsigned int kobjsize(const void 
 #define VM_INSERTPAGE	0x02000000	/* The vma has had "vm_insert_page()" done on it */
 #define VM_ALWAYSDUMP	0x04000000	/* Always include in core dumps */
 
-#define VM_CAN_INVALIDATE 0x08000000	/* The mapping may be invalidated,
-					 * eg. truncate or invalidate_inode_*.
-					 * In this case, do_no_page must
-					 * return with the page locked.
-					 */
-#define VM_CAN_NONLINEAR 0x10000000	/* Has ->fault & does nonlinear pages */
+#define VM_CAN_NONLINEAR 0x08000000	/* Has ->fault & does nonlinear pages */
 
 #ifndef VM_STACK_DEFAULT_FLAGS		/* arch can override this */
 #define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
@@ -199,24 +194,44 @@ extern unsigned int kobjsize(const void 
  */
 extern pgprot_t protection_map[16];
 
-#define FAULT_FLAG_WRITE	0x01
-#define FAULT_FLAG_NONLINEAR	0x02
+#define FAULT_FLAG_WRITE	0x01	/* Fault was a write access */
+#define FAULT_FLAG_NONLINEAR	0x02	/* Fault was via a nonlinear mapping */
+
+
+#define FAULT_RET_NOPAGE	0x0100	/* ->fault did not return a page. This
+					 * can be used if the handler installs
+					 * their own pte.
+					 */
+#define FAULT_RET_LOCKED	0x0200	/* ->fault locked the page, caller must
+					 * unlock after installing the mapping.
+					 * This is used by pagecache in
+					 * particular, where the page lock is
+					 * used to synchronise against truncate
+					 * and invalidate. Mutually exclusive
+					 * with FAULT_RET_NOPAGE.
+					 */
 
 /*
- * fault_data is filled in the the pagefault handler and passed to the
- * vma's ->fault function. That function is responsible for filling in
- * 'type', which is the type of fault if a page is returned, or the type
- * of error if NULL is returned.
- *
- * pgoff should be used in favour of address, if possible. If pgoff is
- * used, one may set VM_CAN_NONLINEAR in the vma->vm_flags to get
- * nonlinear mapping support.
- */
-struct fault_data {
-	unsigned long address;
-	pgoff_t pgoff;
-	unsigned int flags;
-	int type;
+ * vm_fault is filled by the the pagefault handler and passed to the vma's
+ * ->fault function. The vma's ->fault is responsible for returning the
+ * VM_FAULT_xxx type which occupies the lowest byte of the return code, ORed
+ * with FAULT_RET_ flags that occupy the next byte and give details about
+ * how the fault was handled.
+ *
+ * pgoff should be used in favour of virtual_address, if possible. If pgoff
+ * is used, one may set VM_CAN_NONLINEAR in the vma->vm_flags to get nonlinear
+ * mapping support.
+ */
+struct vm_fault {
+	unsigned int flags;		/* FAULT_FLAG_xxx flags */
+	pgoff_t pgoff;			/* Logical page offset based on vma */
+	void __user *virtual_address;	/* Faulting virtual address */
+
+	struct page *page;		/* ->fault handlers should return a
+					 * page here, unless FAULT_RET_NOPAGE
+					 * is set (which is also implied by
+					 * VM_FAULT_OOM or SIGBUS).
+					 */
 };
 
 /*
@@ -227,15 +242,11 @@ struct fault_data {
 struct vm_operations_struct {
 	void (*open)(struct vm_area_struct * area);
 	void (*close)(struct vm_area_struct * area);
-	struct page *(*fault)(struct vm_area_struct *vma,
-			struct fault_data *fdata);
+	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);
-	int (*populate)(struct vm_area_struct *area, unsigned long address,
-			unsigned long len, pgprot_t prot, unsigned long pgoff,
-			int nonblock);
 
 	/* notification that a previously read-only page is about to become
 	 * writable, if an error is returned it will cause a SIGBUS */
@@ -697,8 +708,14 @@ static inline int page_mapped(struct pag
  * Used to decide whether a process gets delivered SIGBUS or
  * just gets major/minor fault counters bumped up.
  */
-#define VM_FAULT_OOM	0x00
-#define VM_FAULT_SIGBUS	0x01
+
+/*
+ * VM_FAULT_ERROR is set for the error cases, to make some tests simpler.
+ */
+#define VM_FAULT_ERROR	0x20
+
+#define VM_FAULT_OOM	(0x00 | VM_FAULT_ERROR)
+#define VM_FAULT_SIGBUS	(0x01 | VM_FAULT_ERROR)
 #define VM_FAULT_MINOR	0x02
 #define VM_FAULT_MAJOR	0x03
 
@@ -708,6 +725,11 @@ static inline int page_mapped(struct pag
  */
 #define VM_FAULT_WRITE	0x10
 
+/*
+ * Mask of VM_FAULT_ flags
+ */
+#define VM_FAULT_MASK	0xff
+
 #define offset_in_page(p)	((unsigned long)(p) & ~PAGE_MASK)
 
 extern void show_free_areas(void);
@@ -790,8 +812,6 @@ static inline void unmap_shared_mapping_
 
 extern int vmtruncate(struct inode * inode, loff_t offset);
 extern int vmtruncate_range(struct inode * inode, loff_t offset, loff_t end);
-extern int install_page(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, struct page *page, pgprot_t prot);
-extern int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, unsigned long pgoff, pgprot_t prot);
 
 #ifdef CONFIG_MMU
 extern int __handle_mm_fault(struct mm_struct *mm,struct vm_area_struct *vma,
@@ -1124,11 +1144,7 @@ extern void truncate_inode_pages_range(s
 				       loff_t lstart, loff_t lend);
 
 /* generic vm_area_ops exported for stackable file systems */
-extern struct page *filemap_fault(struct vm_area_struct *, struct fault_data *);
-extern struct page * __deprecated_for_modules
-filemap_nopage(struct vm_area_struct *, unsigned long, int *);
-extern int __deprecated_for_modules filemap_populate(struct vm_area_struct *,
-		unsigned long, unsigned long, pgprot_t, unsigned long, int);
+extern int filemap_fault(struct vm_area_struct *, struct vm_fault *);
 
 /* mm/page-writeback.c */
 int write_one_page(struct page *page, int wait);
Index: linux-2.6/ipc/shm.c
===================================================================
--- linux-2.6.orig/ipc/shm.c
+++ linux-2.6/ipc/shm.c
@@ -226,13 +226,12 @@ static void shm_close(struct vm_area_str
 	mutex_unlock(&shm_ids(ns).mutex);
 }
 
-static struct page *shm_fault(struct vm_area_struct *vma,
-					struct fault_data *fdata)
+static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	struct file *file = vma->vm_file;
 	struct shm_file_data *sfd = shm_file_data(file);
 
-	return sfd->vm_ops->fault(vma, fdata);
+	return sfd->vm_ops->fault(vma, vmf);
 }
 
 #ifdef CONFIG_NUMA
Index: linux-2.6/mm/filemap.c
===================================================================
--- linux-2.6.orig/mm/filemap.c
+++ linux-2.6/mm/filemap.c
@@ -1336,7 +1336,7 @@ static int fastcall page_cache_read(stru
 /**
  * filemap_fault - read in file data for page fault handling
  * @vma:	user vma (not used)
- * @fdata:	the applicable fault_data
+ * @vmf:	the applicable fault_data
  *
  * filemap_fault() is invoked via the vma operations vector for a
  * mapped memory region to read in file data during a page fault.
@@ -1345,7 +1345,7 @@ static int fastcall page_cache_read(stru
  * it in the page cache, and handles the special cases reasonably without
  * having a lot of duplicated code.
  */
-struct page *filemap_fault(struct vm_area_struct *vma, struct fault_data *fdata)
+int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	int error;
 	struct file *file = vma->vm_file;
@@ -1355,13 +1355,12 @@ struct page *filemap_fault(struct vm_are
 	struct page *page;
 	unsigned long size;
 	int did_readaround = 0;
+	int ret;
 
-	fdata->type = VM_FAULT_MINOR;
-
-	BUG_ON(!(vma->vm_flags & VM_CAN_INVALIDATE));
+	ret = VM_FAULT_MINOR;
 
 	size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
-	if (fdata->pgoff >= size)
+	if (vmf->pgoff >= size)
 		goto outside_data_content;
 
 	/* If we don't want any read-ahead, don't bother */
@@ -1375,18 +1374,18 @@ struct page *filemap_fault(struct vm_are
 	 * For sequential accesses, we use the generic readahead logic.
 	 */
 	if (VM_SequentialReadHint(vma))
-		page_cache_readahead(mapping, ra, file, fdata->pgoff, 1);
+		page_cache_readahead(mapping, ra, file, vmf->pgoff, 1);
 
 	/*
 	 * Do we have something in the page cache already?
 	 */
 retry_find:
-	page = find_lock_page(mapping, fdata->pgoff);
+	page = find_lock_page(mapping, vmf->pgoff);
 	if (!page) {
 		unsigned long ra_pages;
 
 		if (VM_SequentialReadHint(vma)) {
-			handle_ra_miss(mapping, ra, fdata->pgoff);
+			handle_ra_miss(mapping, ra, vmf->pgoff);
 			goto no_cached_page;
 		}
 		ra->mmap_miss++;
@@ -1403,7 +1402,7 @@ retry_find:
 		 * check did_readaround, as this is an inner loop.
 		 */
 		if (!did_readaround) {
-			fdata->type = VM_FAULT_MAJOR;
+			ret = VM_FAULT_MAJOR;
 			count_vm_event(PGMAJFAULT);
 		}
 		did_readaround = 1;
@@ -1411,11 +1410,11 @@ retry_find:
 		if (ra_pages) {
 			pgoff_t start = 0;
 
-			if (fdata->pgoff > ra_pages / 2)
-				start = fdata->pgoff - ra_pages / 2;
+			if (vmf->pgoff > ra_pages / 2)
+				start = vmf->pgoff - ra_pages / 2;
 			do_page_cache_readahead(mapping, file, start, ra_pages);
 		}
-		page = find_lock_page(mapping, fdata->pgoff);
+		page = find_lock_page(mapping, vmf->pgoff);
 		if (!page)
 			goto no_cached_page;
 	}
@@ -1432,7 +1431,7 @@ retry_find:
 
 	/* Must recheck i_size under page lock */
 	size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
-	if (unlikely(fdata->pgoff >= size)) {
+	if (unlikely(vmf->pgoff >= size)) {
 		unlock_page(page);
 		goto outside_data_content;
 	}
@@ -1441,24 +1440,24 @@ retry_find:
 	 * Found the page and have a reference on it.
 	 */
 	mark_page_accessed(page);
-	return page;
+	vmf->page = page;
+	return ret | FAULT_RET_LOCKED;
 
 outside_data_content:
 	/*
 	 * An external ptracer can access pages that normally aren't
 	 * accessible..
 	 */
-	if (vma->vm_mm == current->mm) {
-		fdata->type = VM_FAULT_SIGBUS;
-		return NULL;
-	}
+	if (vma->vm_mm == current->mm)
+		return VM_FAULT_SIGBUS;
+
 	/* Fall through to the non-read-ahead case */
 no_cached_page:
 	/*
 	 * We're only likely to ever get here if MADV_RANDOM is in
 	 * effect.
 	 */
-	error = page_cache_read(file, fdata->pgoff);
+	error = page_cache_read(file, vmf->pgoff);
 
 	/*
 	 * The page we want has now been added to the page cache.
@@ -1474,15 +1473,13 @@ no_cached_page:
 	 * to schedule I/O.
 	 */
 	if (error == -ENOMEM)
-		fdata->type = VM_FAULT_OOM;
-	else
-		fdata->type = VM_FAULT_SIGBUS;
-	return NULL;
+		return VM_FAULT_OOM;
+	return VM_FAULT_SIGBUS;
 
 page_not_uptodate:
 	/* IO error path */
 	if (!did_readaround) {
-		fdata->type = VM_FAULT_MAJOR;
+		ret = VM_FAULT_MAJOR;
 		count_vm_event(PGMAJFAULT);
 	}
 
@@ -1501,206 +1498,10 @@ page_not_uptodate:
 
 	/* Things didn't work out. Return zero to tell the mm layer so. */
 	shrink_readahead_size_eio(file, ra);
-	fdata->type = VM_FAULT_SIGBUS;
-	return NULL;
+	return VM_FAULT_SIGBUS;
 }
 EXPORT_SYMBOL(filemap_fault);
 
-/*
- * filemap_nopage and filemap_populate are legacy exports that are not used
- * in tree. Scheduled for removal.
- */
-struct page *filemap_nopage(struct vm_area_struct *area,
-				unsigned long address, int *type)
-{
-	struct page *page;
-	struct fault_data fdata;
-	fdata.address = address;
-	fdata.pgoff = ((address - area->vm_start) >> PAGE_CACHE_SHIFT)
-			+ area->vm_pgoff;
-	fdata.flags = 0;
-
-	page = filemap_fault(area, &fdata);
-	if (type)
-		*type = fdata.type;
-
-	return page;
-}
-EXPORT_SYMBOL(filemap_nopage);
-
-static struct page * filemap_getpage(struct file *file, unsigned long pgoff,
-					int nonblock)
-{
-	struct address_space *mapping = file->f_mapping;
-	struct page *page;
-	int error;
-
-	/*
-	 * Do we have something in the page cache already?
-	 */
-retry_find:
-	page = find_get_page(mapping, pgoff);
-	if (!page) {
-		if (nonblock)
-			return NULL;
-		goto no_cached_page;
-	}
-
-	/*
-	 * Ok, found a page in the page cache, now we need to check
-	 * that it's up-to-date.
-	 */
-	if (!PageUptodate(page)) {
-		if (nonblock) {
-			page_cache_release(page);
-			return NULL;
-		}
-		goto page_not_uptodate;
-	}
-
-success:
-	/*
-	 * Found the page and have a reference on it.
-	 */
-	mark_page_accessed(page);
-	return page;
-
-no_cached_page:
-	error = page_cache_read(file, pgoff);
-
-	/*
-	 * The page we want has now been added to the page cache.
-	 * In the unlikely event that someone removed it in the
-	 * meantime, we'll just come back here and read it again.
-	 */
-	if (error >= 0)
-		goto retry_find;
-
-	/*
-	 * An error return from page_cache_read can result if the
-	 * system is low on memory, or a problem occurs while trying
-	 * to schedule I/O.
-	 */
-	return NULL;
-
-page_not_uptodate:
-	lock_page(page);
-
-	/* Did it get truncated while we waited for it? */
-	if (!page->mapping) {
-		unlock_page(page);
-		goto err;
-	}
-
-	/* Did somebody else get it up-to-date? */
-	if (PageUptodate(page)) {
-		unlock_page(page);
-		goto success;
-	}
-
-	error = mapping->a_ops->readpage(file, page);
-	if (!error) {
-		wait_on_page_locked(page);
-		if (PageUptodate(page))
-			goto success;
-	} else if (error == AOP_TRUNCATED_PAGE) {
-		page_cache_release(page);
-		goto retry_find;
-	}
-
-	/*
-	 * Umm, take care of errors if the page isn't up-to-date.
-	 * Try to re-read it _once_. We do this synchronously,
-	 * because there really aren't any performance issues here
-	 * and we need to check for errors.
-	 */
-	lock_page(page);
-
-	/* Somebody truncated the page on us? */
-	if (!page->mapping) {
-		unlock_page(page);
-		goto err;
-	}
-	/* Somebody else successfully read it in? */
-	if (PageUptodate(page)) {
-		unlock_page(page);
-		goto success;
-	}
-
-	ClearPageError(page);
-	error = mapping->a_ops->readpage(file, page);
-	if (!error) {
-		wait_on_page_locked(page);
-		if (PageUptodate(page))
-			goto success;
-	} else if (error == AOP_TRUNCATED_PAGE) {
-		page_cache_release(page);
-		goto retry_find;
-	}
-
-	/*
-	 * Things didn't work out. Return zero to tell the
-	 * mm layer so, possibly freeing the page cache page first.
-	 */
-err:
-	page_cache_release(page);
-
-	return NULL;
-}
-
-int filemap_populate(struct vm_area_struct *vma, unsigned long addr,
-		unsigned long len, pgprot_t prot, unsigned long pgoff,
-		int nonblock)
-{
-	struct file *file = vma->vm_file;
-	struct address_space *mapping = file->f_mapping;
-	struct inode *inode = mapping->host;
-	unsigned long size;
-	struct mm_struct *mm = vma->vm_mm;
-	struct page *page;
-	int err;
-
-	if (!nonblock)
-		force_page_cache_readahead(mapping, vma->vm_file,
-					pgoff, len >> PAGE_CACHE_SHIFT);
-
-repeat:
-	size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
-	if (pgoff + (len >> PAGE_CACHE_SHIFT) > size)
-		return -EINVAL;
-
-	page = filemap_getpage(file, pgoff, nonblock);
-
-	/* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as
-	 * done in shmem_populate calling shmem_getpage */
-	if (!page && !nonblock)
-		return -ENOMEM;
-
-	if (page) {
-		err = install_page(mm, vma, addr, page, prot);
-		if (err) {
-			page_cache_release(page);
-			return err;
-		}
-	} else if (vma->vm_flags & VM_NONLINEAR) {
-		/* No page was found just because we can't read it in now (being
-		 * here implies nonblock != 0), but the page may exist, so set
-		 * the PTE to fault it in later. */
-		err = install_file_pte(mm, vma, addr, pgoff, prot);
-		if (err)
-			return err;
-	}
-
-	len -= PAGE_SIZE;
-	addr += PAGE_SIZE;
-	pgoff++;
-	if (len)
-		goto repeat;
-
-	return 0;
-}
-EXPORT_SYMBOL(filemap_populate);
-
 struct vm_operations_struct generic_file_vm_ops = {
 	.fault		= filemap_fault,
 };
@@ -1715,7 +1516,7 @@ int generic_file_mmap(struct file * file
 		return -ENOEXEC;
 	file_accessed(file);
 	vma->vm_ops = &generic_file_vm_ops;
-	vma->vm_flags |= VM_CAN_INVALIDATE | VM_CAN_NONLINEAR;
+	vma->vm_flags |= VM_CAN_NONLINEAR;
 	return 0;
 }
 
Index: linux-2.6/mm/filemap_xip.c
===================================================================
--- linux-2.6.orig/mm/filemap_xip.c
+++ linux-2.6/mm/filemap_xip.c
@@ -232,8 +232,7 @@ __xip_unmap (struct address_space * mapp
  *
  * This function is derived from filemap_fault, but used for execute in place
  */
-static struct page *xip_file_fault(struct vm_area_struct *area,
-					struct fault_data *fdata)
+static int xip_file_fault(struct vm_area_struct *area, struct vm_fault *vmf)
 {
 	struct file *file = area->vm_file;
 	struct address_space *mapping = file->f_mapping;
@@ -244,19 +243,15 @@ static struct page *xip_file_fault(struc
 	/* XXX: are VM_FAULT_ codes OK? */
 
 	size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
-	if (fdata->pgoff >= size) {
-		fdata->type = VM_FAULT_SIGBUS;
-		return NULL;
-	}
+	if (vmf->pgoff >= size)
+		return VM_FAULT_SIGBUS;
 
 	page = mapping->a_ops->get_xip_page(mapping,
-					fdata->pgoff*(PAGE_SIZE/512), 0);
+					vmf->pgoff*(PAGE_SIZE/512), 0);
 	if (!IS_ERR(page))
 		goto out;
-	if (PTR_ERR(page) != -ENODATA) {
-		fdata->type = VM_FAULT_OOM;
-		return NULL;
-	}
+	if (PTR_ERR(page) != -ENODATA)
+		return VM_FAULT_OOM;
 
 	/* sparse block */
 	if ((area->vm_flags & (VM_WRITE | VM_MAYWRITE)) &&
@@ -264,26 +259,22 @@ static struct page *xip_file_fault(struc
 	    (!(mapping->host->i_sb->s_flags & MS_RDONLY))) {
 		/* maybe shared writable, allocate new block */
 		page = mapping->a_ops->get_xip_page(mapping,
-					fdata->pgoff*(PAGE_SIZE/512), 1);
-		if (IS_ERR(page)) {
-			fdata->type = VM_FAULT_SIGBUS;
-			return NULL;
-		}
+					vmf->pgoff*(PAGE_SIZE/512), 1);
+		if (IS_ERR(page))
+			return VM_FAULT_SIGBUS;
 		/* unmap page at pgoff from all other vmas */
-		__xip_unmap(mapping, fdata->pgoff);
+		__xip_unmap(mapping, vmf->pgoff);
 	} else {
 		/* not shared and writable, use xip_sparse_page() */
 		page = xip_sparse_page();
-		if (!page) {
-			fdata->type = VM_FAULT_OOM;
-			return NULL;
-		}
+		if (!page)
+			return VM_FAULT_OOM;
 	}
 
 out:
-	fdata->type = VM_FAULT_MINOR;
 	page_cache_get(page);
-	return page;
+	vmf->page = page;
+	return VM_FAULT_MINOR;
 }
 
 static struct vm_operations_struct xip_file_vm_ops = {
Index: linux-2.6/mm/memory.c
===================================================================
--- linux-2.6.orig/mm/memory.c
+++ linux-2.6/mm/memory.c
@@ -1827,10 +1827,10 @@ static int unmap_mapping_range_vma(struc
 
 	/*
 	 * files that support invalidating or truncating portions of the
-	 * file from under mmaped areas must set the VM_CAN_INVALIDATE flag, and
-	 * have their .nopage function return the page locked.
+	 * file from under mmaped areas must have their ->fault function
+	 * return a locked page (and FAULT_RET_LOCKED code). This provides
+	 * synchronisation against concurrent unmapping here.
 	 */
-	BUG_ON(!(vma->vm_flags & VM_CAN_INVALIDATE));
 
 again:
 	restart_addr = vma->vm_truncate_count;
@@ -2299,63 +2299,62 @@ static int __do_fault(struct mm_struct *
 		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
 {
 	spinlock_t *ptl;
-	struct page *page, *faulted_page;
+	struct page *page;
 	pte_t entry;
 	int anon = 0;
 	struct page *dirty_page = NULL;
-	struct fault_data fdata;
+	struct vm_fault vmf;
+	int ret;
 
-	fdata.address = address & PAGE_MASK;
-	fdata.pgoff = pgoff;
-	fdata.flags = flags;
+	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
+	vmf.pgoff = pgoff;
+	vmf.flags = flags;
+	vmf.page = NULL;
 
 	pte_unmap(page_table);
 	BUG_ON(vma->vm_flags & VM_PFNMAP);
 
 	if (likely(vma->vm_ops->fault)) {
-		fdata.type = -1;
-		faulted_page = vma->vm_ops->fault(vma, &fdata);
-		WARN_ON(fdata.type == -1);
-		if (unlikely(!faulted_page))
-			return fdata.type;
+		ret = vma->vm_ops->fault(vma, &vmf);
+		if (unlikely(ret & (VM_FAULT_ERROR | FAULT_RET_NOPAGE)))
+			return (ret & VM_FAULT_MASK);
 	} else {
 		/* Legacy ->nopage path */
-		fdata.type = VM_FAULT_MINOR;
-		faulted_page = vma->vm_ops->nopage(vma, address & PAGE_MASK,
-								&fdata.type);
+		ret = VM_FAULT_MINOR;
+		vmf.page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
 		/* no page was available -- either SIGBUS or OOM */
-		if (unlikely(faulted_page == NOPAGE_SIGBUS))
+		if (unlikely(vmf.page == NOPAGE_SIGBUS))
 			return VM_FAULT_SIGBUS;
-		else if (unlikely(faulted_page == NOPAGE_OOM))
+		else if (unlikely(vmf.page == NOPAGE_OOM))
 			return VM_FAULT_OOM;
 	}
 
 	/*
-	 * For consistency in subsequent calls, make the faulted_page always
+	 * For consistency in subsequent calls, make the faulted page always
 	 * locked.
 	 */
-	if (unlikely(!(vma->vm_flags & VM_CAN_INVALIDATE)))
-		lock_page(faulted_page);
+	if (unlikely(!(ret & FAULT_RET_LOCKED)))
+		lock_page(vmf.page);
 	else
-		BUG_ON(!PageLocked(faulted_page));
+		VM_BUG_ON(!PageLocked(vmf.page));
 
 	/*
 	 * Should we do an early C-O-W break?
 	 */
-	page = faulted_page;
+	page = vmf.page;
 	if (flags & FAULT_FLAG_WRITE) {
 		if (!(vma->vm_flags & VM_SHARED)) {
 			anon = 1;
 			if (unlikely(anon_vma_prepare(vma))) {
-				fdata.type = VM_FAULT_OOM;
+				ret = VM_FAULT_OOM;
 				goto out;
 			}
 			page = alloc_page_vma(GFP_HIGHUSER, vma, address);
 			if (!page) {
-				fdata.type = VM_FAULT_OOM;
+				ret = VM_FAULT_OOM;
 				goto out;
 			}
-			copy_user_highpage(page, faulted_page, address, vma);
+			copy_user_highpage(page, vmf.page, address, vma);
 		} else {
 			/*
 			 * If the page will be shareable, see if the backing
@@ -2364,8 +2363,8 @@ static int __do_fault(struct mm_struct *
 			 */
 			if (vma->vm_ops->page_mkwrite &&
 			    vma->vm_ops->page_mkwrite(vma, page) < 0) {
-				fdata.type = VM_FAULT_SIGBUS;
-				anon = 1; /* no anon but release faulted_page */
+				ret = VM_FAULT_SIGBUS;
+				anon = 1; /* no anon but release vmf.page */
 				goto out;
 			}
 		}
@@ -2417,15 +2416,15 @@ static int __do_fault(struct mm_struct *
 	pte_unmap_unlock(page_table, ptl);
 
 out:
-	unlock_page(faulted_page);
+	unlock_page(vmf.page);
 	if (anon)
-		page_cache_release(faulted_page);
+		page_cache_release(vmf.page);
 	else if (dirty_page) {
 		set_page_dirty_balance(dirty_page);
 		put_page(dirty_page);
 	}
 
-	return fdata.type;
+	return (ret & VM_FAULT_MASK);
 }
 
 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
@@ -2436,18 +2435,10 @@ static int do_linear_fault(struct mm_str
 			- vma->vm_start) >> PAGE_CACHE_SHIFT) + vma->vm_pgoff;
 	unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0);
 
-	return __do_fault(mm, vma, address, page_table, pmd, pgoff, flags, orig_pte);
+	return __do_fault(mm, vma, address, page_table, pmd, pgoff,
+							flags, orig_pte);
 }
 
-static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
-		unsigned long address, pte_t *page_table, pmd_t *pmd,
-		int write_access, pgoff_t pgoff, pte_t orig_pte)
-{
-	unsigned int flags = FAULT_FLAG_NONLINEAR |
-				(write_access ? FAULT_FLAG_WRITE : 0);
-
-	return __do_fault(mm, vma, address, page_table, pmd, pgoff, flags, orig_pte);
-}
 
 /*
  * do_no_pfn() tries to create a new page mapping for a page without
@@ -2508,17 +2499,19 @@ static noinline int do_no_pfn(struct mm_
  * but allow concurrent faults), and pte mapped but not yet locked.
  * We return with mmap_sem still held, but pte unmapped and unlocked.
  */
-static int do_file_page(struct mm_struct *mm, struct vm_area_struct *vma,
+static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 		unsigned long address, pte_t *page_table, pmd_t *pmd,
 		int write_access, pte_t orig_pte)
 {
+	unsigned int flags = FAULT_FLAG_NONLINEAR |
+				(write_access ? FAULT_FLAG_WRITE : 0);
 	pgoff_t pgoff;
-	int err;
 
 	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
 		return VM_FAULT_MINOR;
 
-	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
+	if (unlikely(!(vma->vm_flags & VM_NONLINEAR) ||
+			!(vma->vm_flags & VM_CAN_NONLINEAR))) {
 		/*
 		 * Page table corrupted: show pte and kill process.
 		 */
@@ -2528,18 +2521,8 @@ static int do_file_page(struct mm_struct
 
 	pgoff = pte_to_pgoff(orig_pte);
 
-	if (vma->vm_ops && vma->vm_ops->fault)
-		return do_nonlinear_fault(mm, vma, address, page_table, pmd,
-					write_access, pgoff, orig_pte);
-
-	/* We can then assume vm->vm_ops && vma->vm_ops->populate */
-	err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE,
-					vma->vm_page_prot, pgoff, 0);
-	if (err == -ENOMEM)
-		return VM_FAULT_OOM;
-	if (err)
-		return VM_FAULT_SIGBUS;
-	return VM_FAULT_MAJOR;
+	return __do_fault(mm, vma, address, page_table, pmd, pgoff,
+							flags, orig_pte);
 }
 
 /*
@@ -2578,7 +2561,7 @@ static inline int handle_pte_fault(struc
 						 pte, pmd, write_access);
 		}
 		if (pte_file(entry))
-			return do_file_page(mm, vma, address,
+			return do_nonlinear_fault(mm, vma, address,
 					pte, pmd, write_access, entry);
 		return do_swap_page(mm, vma, address,
 					pte, pmd, write_access, entry);
Index: linux-2.6/mm/nommu.c
===================================================================
--- linux-2.6.orig/mm/nommu.c
+++ linux-2.6/mm/nommu.c
@@ -1336,10 +1336,10 @@ int in_gate_area_no_task(unsigned long a
 	return 0;
 }
 
-struct page *filemap_fault(struct vm_area_struct *vma, struct fault_data *fdata)
+int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	BUG();
-	return NULL;
+	return 0;
 }
 
 /*
Index: linux-2.6/mm/shmem.c
===================================================================
--- linux-2.6.orig/mm/shmem.c
+++ linux-2.6/mm/shmem.c
@@ -1303,29 +1303,21 @@ failed:
 	return error;
 }
 
-static struct page *shmem_fault(struct vm_area_struct *vma,
-					struct fault_data *fdata)
+static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
-	struct page *page = NULL;
 	int error;
+	int ret;
 
-	BUG_ON(!(vma->vm_flags & VM_CAN_INVALIDATE));
+	if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
+		return VM_FAULT_SIGBUS;
 
-	if (((loff_t)fdata->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
-		fdata->type = VM_FAULT_SIGBUS;
-		return NULL;
-	}
-
-	error = shmem_getpage(inode, fdata->pgoff, &page,
-						SGP_FAULT, &fdata->type);
-	if (error) {
-		fdata->type = ((error == -ENOMEM)?VM_FAULT_OOM:VM_FAULT_SIGBUS);
-		return NULL;
-	}
+	error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_FAULT, &ret);
+	if (error)
+		return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
 
-	mark_page_accessed(page);
-	return page;
+	mark_page_accessed(vmf->page);
+	return ret | FAULT_RET_LOCKED;
 }
 
 #ifdef CONFIG_NUMA
@@ -1372,7 +1364,7 @@ static int shmem_mmap(struct file *file,
 {
 	file_accessed(file);
 	vma->vm_ops = &shmem_vm_ops;
-	vma->vm_flags |= VM_CAN_INVALIDATE | VM_CAN_NONLINEAR;
+	vma->vm_flags |= VM_CAN_NONLINEAR;
 	return 0;
 }
 
@@ -2562,6 +2554,5 @@ int shmem_zero_setup(struct vm_area_stru
 		fput(vma->vm_file);
 	vma->vm_file = file;
 	vma->vm_ops = &shmem_vm_ops;
-	vma->vm_flags |= VM_CAN_INVALIDATE;
 	return 0;
 }
Index: linux-2.6/fs/gfs2/ops_file.c
===================================================================
--- linux-2.6.orig/fs/gfs2/ops_file.c
+++ linux-2.6/fs/gfs2/ops_file.c
@@ -364,8 +364,6 @@ static int gfs2_mmap(struct file *file, 
 	else
 		vma->vm_ops = &gfs2_vm_ops_private;
 
-	vma->vm_flags |= VM_CAN_INVALIDATE|VM_CAN_NONLINEAR;
-
 	gfs2_glock_dq_uninit(&i_gh);
 
 	return error;
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
@@ -160,26 +160,8 @@ Who:	Greg Kroah-Hartman <gregkh@suse.de>
 
 ---------------------------
 
-What:	filemap_nopage, filemap_populate
-When:	April 2007
-Why:	These legacy interfaces no longer have any callers in the kernel and
-	any functionality provided can be provided with filemap_fault. The
-	removal schedule is short because they are a big maintainence burden
-	and have some bugs.
-Who:	Nick Piggin <npiggin@suse.de>
-
----------------------------
-
-What:	vm_ops.populate, install_page
-When:	April 2007
-Why:	These legacy interfaces no longer have any callers in the kernel and
-	any functionality provided can be provided with vm_ops.fault.
-Who:	Nick Piggin <npiggin@suse.de>
-
----------------------------
-
 What:	vm_ops.nopage
-When:	February 2008, provided in-kernel callers have been converted
+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.
Index: linux-2.6/Documentation/filesystems/Locking
===================================================================
--- linux-2.6.orig/Documentation/filesystems/Locking
+++ linux-2.6/Documentation/filesystems/Locking
@@ -510,7 +510,7 @@ More details about quota locking can be 
 prototypes:
 	void (*open)(struct vm_area_struct*);
 	void (*close)(struct vm_area_struct*);
-	struct page *(*fault)(struct vm_area_struct*, struct fault_data *);
+	int (*fault)(struct vm_area_struct*, struct vm_fault *);
 	struct page *(*nopage)(struct vm_area_struct*, unsigned long, int *);
 
 locking rules:

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