1 files changed, 55 insertions, 26 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index 67d11ad6df24..d91ecb00d38c 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -558,6 +558,50 @@ static int find_vma_links(struct mm_struct *mm, unsigned long addr,
 	return 0;
 }
 
+/*
+ * vma_next() - Get the next VMA.
+ * @mm: The mm_struct.
+ * @vma: The current vma.
+ *
+ * If @vma is NULL, return the first vma in the mm.
+ *
+ * Returns: The next VMA after @vma.
+ */
+static inline struct vm_area_struct *vma_next(struct mm_struct *mm,
+					 struct vm_area_struct *vma)
+{
+	if (!vma)
+		return mm->mmap;
+
+	return vma->vm_next;
+}
+
+/*
+ * munmap_vma_range() - munmap VMAs that overlap a range.
+ * @mm: The mm struct
+ * @start: The start of the range.
+ * @len: The length of the range.
+ * @pprev: pointer to the pointer that will be set to previous vm_area_struct
+ * @rb_link: the rb_node
+ * @rb_parent: the parent rb_node
+ *
+ * Find all the vm_area_struct that overlap from @start to
+ * @end and munmap them.  Set @pprev to the previous vm_area_struct.
+ *
+ * Returns: -ENOMEM on munmap failure or 0 on success.
+ */
+static inline int
+munmap_vma_range(struct mm_struct *mm, unsigned long start, unsigned long len,
+		 struct vm_area_struct **pprev, struct rb_node ***link,
+		 struct rb_node **parent, struct list_head *uf)
+{
+
+	while (find_vma_links(mm, start, start + len, pprev, link, parent))
+		if (do_munmap(mm, start, len, uf))
+			return -ENOMEM;
+
+	return 0;
+}
 static unsigned long count_vma_pages_range(struct mm_struct *mm,
 		unsigned long addr, unsigned long end)
 {
@@ -619,7 +663,7 @@ static void __vma_link_file(struct vm_area_struct *vma)
 		struct address_space *mapping = file->f_mapping;
 
 		if (vma->vm_flags & VM_DENYWRITE)
-			atomic_dec(&file_inode(file)->i_writecount);
+			put_write_access(file_inode(file));
 		if (vma->vm_flags & VM_SHARED)
 			mapping_allow_writable(mapping);
 
@@ -1128,10 +1172,7 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
 	if (vm_flags & VM_SPECIAL)
 		return NULL;
 
-	if (prev)
-		next = prev->vm_next;
-	else
-		next = mm->mmap;
+	next = vma_next(mm, prev);
 	area = next;
 	if (area && area->vm_end == end)		/* cases 6, 7, 8 */
 		next = next->vm_next;
@@ -1707,13 +1748,9 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 			return -ENOMEM;
 	}
 
-	/* Clear old maps */
-	while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
-			      &rb_parent)) {
-		if (do_munmap(mm, addr, len, uf))
-			return -ENOMEM;
-	}
-
+	/* Clear old maps, set up prev, rb_link, rb_parent, and uf */
+	if (munmap_vma_range(mm, addr, len, &prev, &rb_link, &rb_parent, uf))
+		return -ENOMEM;
 	/*
 	 * Private writable mapping: check memory availability
 	 */
@@ -2562,7 +2599,7 @@ find_extend_vma(struct mm_struct *mm, unsigned long addr)
 	if (vma && (vma->vm_start <= addr))
 		return vma;
 	/* don't alter vm_end if the coredump is running */
-	if (!prev || !mmget_still_valid(mm) || expand_stack(prev, addr))
+	if (!prev || expand_stack(prev, addr))
 		return NULL;
 	if (prev->vm_flags & VM_LOCKED)
 		populate_vma_page_range(prev, addr, prev->vm_end, NULL);
@@ -2588,9 +2625,6 @@ find_extend_vma(struct mm_struct *mm, unsigned long addr)
 		return vma;
 	if (!(vma->vm_flags & VM_GROWSDOWN))
 		return NULL;
-	/* don't alter vm_start if the coredump is running */
-	if (!mmget_still_valid(mm))
-		return NULL;
 	start = vma->vm_start;
 	if (expand_stack(vma, addr))
 		return NULL;
@@ -2635,7 +2669,7 @@ static void unmap_region(struct mm_struct *mm,
 		struct vm_area_struct *vma, struct vm_area_struct *prev,
 		unsigned long start, unsigned long end)
 {
-	struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap;
+	struct vm_area_struct *next = vma_next(mm, prev);
 	struct mmu_gather tlb;
 
 	lru_add_drain();
@@ -2834,7 +2868,7 @@ int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
 		if (error)
 			return error;
 	}
-	vma = prev ? prev->vm_next : mm->mmap;
+	vma = vma_next(mm, prev);
 
 	if (unlikely(uf)) {
 		/*
@@ -3052,14 +3086,9 @@ static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long fla
 	if (error)
 		return error;
 
-	/*
-	 * Clear old maps.  this also does some error checking for us
-	 */
-	while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
-			      &rb_parent)) {
-		if (do_munmap(mm, addr, len, uf))
-			return -ENOMEM;
-	}
+	/* Clear old maps, set up prev, rb_link, rb_parent, and uf */
+	if (munmap_vma_range(mm, addr, len, &prev, &rb_link, &rb_parent, uf))
+		return -ENOMEM;
 
 	/* Check against address space limits *after* clearing old maps... */
 	if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT))