1 files changed, 27 insertions, 131 deletions

diff --git a/mm/gup.c b/mm/gup.c
index 35d550dde7ff..271fbe8195d7 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -406,10 +406,6 @@ static struct page *no_page_table(struct vm_area_struct *vma,
 static int follow_pfn_pte(struct vm_area_struct *vma, unsigned long address,
 		pte_t *pte, unsigned int flags)
 {
-	/* No page to get reference */
-	if (flags & FOLL_GET)
-		return -EFAULT;
-
 	if (flags & FOLL_TOUCH) {
 		pte_t entry = *pte;
 
@@ -1116,8 +1112,15 @@ retry:
 		} else if (PTR_ERR(page) == -EEXIST) {
 			/*
 			 * Proper page table entry exists, but no corresponding
-			 * struct page.
+			 * struct page. If the caller expects **pages to be
+			 * filled in, bail out now, because that can't be done
+			 * for this page.
 			 */
+			if (pages) {
+				ret = PTR_ERR(page);
+				goto out;
+			}
+
 			goto next_page;
 		} else if (IS_ERR(page)) {
 			ret = PTR_ERR(page);
@@ -1644,11 +1647,11 @@ EXPORT_SYMBOL(fault_in_writeable);
  * @uaddr: start of address range
  * @size: length of address range
  *
- * Faults in an address range using get_user_pages, i.e., without triggering
- * hardware page faults.  This is primarily useful when we already know that
- * some or all of the pages in the address range aren't in memory.
+ * Faults in an address range for writing.  This is primarily useful when we
+ * already know that some or all of the pages in the address range aren't in
+ * memory.
  *
- * Other than fault_in_writeable(), this function is non-destructive.
+ * Unlike fault_in_writeable(), this function is non-destructive.
  *
  * Note that we don't pin or otherwise hold the pages referenced that we fault
  * in.  There's no guarantee that they'll stay in memory for any duration of
@@ -1659,46 +1662,27 @@ EXPORT_SYMBOL(fault_in_writeable);
  */
 size_t fault_in_safe_writeable(const char __user *uaddr, size_t size)
 {
-	unsigned long start = (unsigned long)untagged_addr(uaddr);
-	unsigned long end, nstart, nend;
+	unsigned long start = (unsigned long)uaddr, end;
 	struct mm_struct *mm = current->mm;
-	struct vm_area_struct *vma = NULL;
-	int locked = 0;
+	bool unlocked = false;
 
-	nstart = start & PAGE_MASK;
+	if (unlikely(size == 0))
+		return 0;
 	end = PAGE_ALIGN(start + size);
-	if (end < nstart)
+	if (end < start)
 		end = 0;
-	for (; nstart != end; nstart = nend) {
-		unsigned long nr_pages;
-		long ret;
 
-		if (!locked) {
-			locked = 1;
-			mmap_read_lock(mm);
-			vma = find_vma(mm, nstart);
-		} else if (nstart >= vma->vm_end)
-			vma = vma->vm_next;
-		if (!vma || vma->vm_start >= end)
-			break;
-		nend = end ? min(end, vma->vm_end) : vma->vm_end;
-		if (vma->vm_flags & (VM_IO | VM_PFNMAP))
-			continue;
-		if (nstart < vma->vm_start)
-			nstart = vma->vm_start;
-		nr_pages = (nend - nstart) / PAGE_SIZE;
-		ret = __get_user_pages_locked(mm, nstart, nr_pages,
-					      NULL, NULL, &locked,
-					      FOLL_TOUCH | FOLL_WRITE);
-		if (ret <= 0)
+	mmap_read_lock(mm);
+	do {
+		if (fixup_user_fault(mm, start, FAULT_FLAG_WRITE, &unlocked))
 			break;
-		nend = nstart + ret * PAGE_SIZE;
-	}
-	if (locked)
-		mmap_read_unlock(mm);
-	if (nstart == end)
-		return 0;
-	return size - min_t(size_t, nstart - start, size);
+		start = (start + PAGE_SIZE) & PAGE_MASK;
+	} while (start != end);
+	mmap_read_unlock(mm);
+
+	if (size > (unsigned long)uaddr - start)
+		return size - ((unsigned long)uaddr - start);
+	return 0;
 }
 EXPORT_SYMBOL(fault_in_safe_writeable);
 
@@ -2065,65 +2049,6 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
 }
 EXPORT_SYMBOL(get_user_pages);
 
-/**
- * get_user_pages_locked() - variant of get_user_pages()
- *
- * @start:      starting user address
- * @nr_pages:   number of pages from start to pin
- * @gup_flags:  flags modifying lookup behaviour
- * @pages:      array that receives pointers to the pages pinned.
- *              Should be at least nr_pages long. Or NULL, if caller
- *              only intends to ensure the pages are faulted in.
- * @locked:     pointer to lock flag indicating whether lock is held and
- *              subsequently whether VM_FAULT_RETRY functionality can be
- *              utilised. Lock must initially be held.
- *
- * It is suitable to replace the form:
- *
- *      mmap_read_lock(mm);
- *      do_something()
- *      get_user_pages(mm, ..., pages, NULL);
- *      mmap_read_unlock(mm);
- *
- *  to:
- *
- *      int locked = 1;
- *      mmap_read_lock(mm);
- *      do_something()
- *      get_user_pages_locked(mm, ..., pages, &locked);
- *      if (locked)
- *          mmap_read_unlock(mm);
- *
- * We can leverage the VM_FAULT_RETRY functionality in the page fault
- * paths better by using either get_user_pages_locked() or
- * get_user_pages_unlocked().
- *
- */
-long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
-			   unsigned int gup_flags, struct page **pages,
-			   int *locked)
-{
-	/*
-	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
-	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
-	 * vmas.  As there are no users of this flag in this call we simply
-	 * disallow this option for now.
-	 */
-	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
-		return -EINVAL;
-	/*
-	 * FOLL_PIN must only be set internally by the pin_user_pages*() APIs,
-	 * never directly by the caller, so enforce that:
-	 */
-	if (WARN_ON_ONCE(gup_flags & FOLL_PIN))
-		return -EINVAL;
-
-	return __get_user_pages_locked(current->mm, start, nr_pages,
-				       pages, NULL, locked,
-				       gup_flags | FOLL_TOUCH);
-}
-EXPORT_SYMBOL(get_user_pages_locked);
-
 /*
  * get_user_pages_unlocked() is suitable to replace the form:
  *
@@ -3067,32 +2992,3 @@ long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
 	return get_user_pages_unlocked(start, nr_pages, pages, gup_flags);
 }
 EXPORT_SYMBOL(pin_user_pages_unlocked);
-
-/*
- * pin_user_pages_locked() is the FOLL_PIN variant of get_user_pages_locked().
- * Behavior is the same, except that this one sets FOLL_PIN and rejects
- * FOLL_GET.
- */
-long pin_user_pages_locked(unsigned long start, unsigned long nr_pages,
-			   unsigned int gup_flags, struct page **pages,
-			   int *locked)
-{
-	/*
-	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
-	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
-	 * vmas.  As there are no users of this flag in this call we simply
-	 * disallow this option for now.
-	 */
-	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
-		return -EINVAL;
-
-	/* FOLL_GET and FOLL_PIN are mutually exclusive. */
-	if (WARN_ON_ONCE(gup_flags & FOLL_GET))
-		return -EINVAL;
-
-	gup_flags |= FOLL_PIN;
-	return __get_user_pages_locked(current->mm, start, nr_pages,
-				       pages, NULL, locked,
-				       gup_flags | FOLL_TOUCH);
-}
-EXPORT_SYMBOL(pin_user_pages_locked);