1 files changed, 39 insertions, 14 deletions

diff --git a/mm/internal.h b/mm/internal.h
index a182506242c4..97c8e896cd2f 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -330,27 +330,52 @@ static inline void mlock_migrate_page(struct page *newpage, struct page *page)
 extern pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma);
 
 /*
- * At what user virtual address is page expected in @vma?
+ * At what user virtual address is page expected in vma?
+ * Returns -EFAULT if all of the page is outside the range of vma.
+ * If page is a compound head, the entire compound page is considered.
  */
 static inline unsigned long
-__vma_address(struct page *page, struct vm_area_struct *vma)
+vma_address(struct page *page, struct vm_area_struct *vma)
 {
-	pgoff_t pgoff = page_to_pgoff(page);
-	return vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
+	pgoff_t pgoff;
+	unsigned long address;
+
+	VM_BUG_ON_PAGE(PageKsm(page), page);	/* KSM page->index unusable */
+	pgoff = page_to_pgoff(page);
+	if (pgoff >= vma->vm_pgoff) {
+		address = vma->vm_start +
+			((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
+		/* Check for address beyond vma (or wrapped through 0?) */
+		if (address < vma->vm_start || address >= vma->vm_end)
+			address = -EFAULT;
+	} else if (PageHead(page) &&
+		   pgoff + (1UL << compound_order(page)) - 1 >= vma->vm_pgoff) {
+		/* Test above avoids possibility of wrap to 0 on 32-bit */
+		address = vma->vm_start;
+	} else {
+		address = -EFAULT;
+	}
+	return address;
 }
 
+/*
+ * Then at what user virtual address will none of the page be found in vma?
+ * Assumes that vma_address() already returned a good starting address.
+ * If page is a compound head, the entire compound page is considered.
+ */
 static inline unsigned long
-vma_address(struct page *page, struct vm_area_struct *vma)
+vma_address_end(struct page *page, struct vm_area_struct *vma)
 {
-	unsigned long start, end;
-
-	start = __vma_address(page, vma);
-	end = start + PAGE_SIZE * (hpage_nr_pages(page) - 1);
-
-	/* page should be within @vma mapping range */
-	VM_BUG_ON_VMA(end < vma->vm_start || start >= vma->vm_end, vma);
-
-	return max(start, vma->vm_start);
+	pgoff_t pgoff;
+	unsigned long address;
+
+	VM_BUG_ON_PAGE(PageKsm(page), page);	/* KSM page->index unusable */
+	pgoff = page_to_pgoff(page) + (1UL << compound_order(page));
+	address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
+	/* Check for address beyond vma (or wrapped through 0?) */
+	if (address < vma->vm_start || address > vma->vm_end)
+		address = vma->vm_end;
+	return address;
 }
 
 #else /* !CONFIG_MMU */