1 files changed, 52 insertions, 40 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index 292ddc3cef9..d9c77b2dbe9 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -931,13 +931,9 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
 	if (!(flags & MAP_FIXED))
 		addr = round_hint_to_min(addr);
 
-	error = arch_mmap_check(addr, len, flags);
-	if (error)
-		return error;
-
 	/* Careful about overflows.. */
 	len = PAGE_ALIGN(len);
-	if (!len || len > TASK_SIZE)
+	if (!len)
 		return -ENOMEM;
 
 	/* offset overflow? */
@@ -948,24 +944,6 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
 	if (mm->map_count > sysctl_max_map_count)
 		return -ENOMEM;
 
-	if (flags & MAP_HUGETLB) {
-		struct user_struct *user = NULL;
-		if (file)
-			return -EINVAL;
-
-		/*
-		 * VM_NORESERVE is used because the reservations will be
-		 * taken when vm_ops->mmap() is called
-		 * A dummy user value is used because we are not locking
-		 * memory so no accounting is necessary
-		 */
-		len = ALIGN(len, huge_page_size(&default_hstate));
-		file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, VM_NORESERVE,
-						&user, HUGETLB_ANONHUGE_INODE);
-		if (IS_ERR(file))
-			return PTR_ERR(file);
-	}
-
 	/* Obtain the address to map to. we verify (or select) it and ensure
 	 * that it represents a valid section of the address space.
 	 */
@@ -1220,8 +1198,20 @@ munmap_back:
 			goto free_vma;
 	}
 
-	if (vma_wants_writenotify(vma))
+	if (vma_wants_writenotify(vma)) {
+		pgprot_t pprot = vma->vm_page_prot;
+
+		/* Can vma->vm_page_prot have changed??
+		 *
+		 * Answer: Yes, drivers may have changed it in their
+		 *         f_op->mmap method.
+		 *
+		 * Ensures that vmas marked as uncached stay that way.
+		 */
 		vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
+		if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
+			vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+	}
 
 	vma_link(mm, vma, prev, rb_link, rb_parent);
 	file = vma->vm_file;
@@ -1455,6 +1445,14 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
 	unsigned long (*get_area)(struct file *, unsigned long,
 				  unsigned long, unsigned long, unsigned long);
 
+	unsigned long error = arch_mmap_check(addr, len, flags);
+	if (error)
+		return error;
+
+	/* Careful about overflows.. */
+	if (len > TASK_SIZE)
+		return -ENOMEM;
+
 	get_area = current->mm->get_unmapped_area;
 	if (file && file->f_op && file->f_op->get_unmapped_area)
 		get_area = file->f_op->get_unmapped_area;
@@ -1825,10 +1823,10 @@ detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
 }
 
 /*
- * Split a vma into two pieces at address 'addr', a new vma is allocated
- * either for the first part or the tail.
+ * __split_vma() bypasses sysctl_max_map_count checking.  We use this on the
+ * munmap path where it doesn't make sense to fail.
  */
-int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
+static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
 	      unsigned long addr, int new_below)
 {
 	struct mempolicy *pol;
@@ -1838,9 +1836,6 @@ int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
 					~(huge_page_mask(hstate_vma(vma)))))
 		return -EINVAL;
 
-	if (mm->map_count >= sysctl_max_map_count)
-		return -ENOMEM;
-
 	new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
 	if (!new)
 		return -ENOMEM;
@@ -1880,6 +1875,19 @@ int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
 	return 0;
 }
 
+/*
+ * Split a vma into two pieces at address 'addr', a new vma is allocated
+ * either for the first part or the tail.
+ */
+int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
+	      unsigned long addr, int new_below)
+{
+	if (mm->map_count >= sysctl_max_map_count)
+		return -ENOMEM;
+
+	return __split_vma(mm, vma, addr, new_below);
+}
+
 /* Munmap is split into 2 main parts -- this part which finds
  * what needs doing, and the areas themselves, which do the
  * work.  This now handles partial unmappings.
@@ -1915,7 +1923,17 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
 	 * places tmp vma above, and higher split_vma places tmp vma below.
 	 */
 	if (start > vma->vm_start) {
-		int error = split_vma(mm, vma, start, 0);
+		int error;
+
+		/*
+		 * Make sure that map_count on return from munmap() will
+		 * not exceed its limit; but let map_count go just above
+		 * its limit temporarily, to help free resources as expected.
+		 */
+		if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
+			return -ENOMEM;
+
+		error = __split_vma(mm, vma, start, 0);
 		if (error)
 			return error;
 		prev = vma;
@@ -1924,7 +1942,7 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
 	/* Does it split the last one? */
 	last = find_vma(mm, end);
 	if (last && end > last->vm_start) {
-		int error = split_vma(mm, last, end, 1);
+		int error = __split_vma(mm, last, end, 1);
 		if (error)
 			return error;
 	}
@@ -1999,20 +2017,14 @@ unsigned long do_brk(unsigned long addr, unsigned long len)
 	if (!len)
 		return addr;
 
-	if ((addr + len) > TASK_SIZE || (addr + len) < addr)
-		return -EINVAL;
-
-	if (is_hugepage_only_range(mm, addr, len))
-		return -EINVAL;
-
 	error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
 	if (error)
 		return error;
 
 	flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
 
-	error = arch_mmap_check(addr, len, flags);
-	if (error)
+	error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
+	if (error & ~PAGE_MASK)
 		return error;
 
 	/*