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Diffstat (limited to 'mm/mmap.c')
-rw-r--r--mm/mmap.c60
1 files changed, 29 insertions, 31 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index eae90af60ea..3f758c7f4c8 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1603,39 +1603,19 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
EXPORT_SYMBOL(find_vma);
-/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
+/*
+ * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
+ * Note: pprev is set to NULL when return value is NULL.
+ */
struct vm_area_struct *
find_vma_prev(struct mm_struct *mm, unsigned long addr,
struct vm_area_struct **pprev)
{
- struct vm_area_struct *vma = NULL, *prev = NULL;
- struct rb_node *rb_node;
- if (!mm)
- goto out;
-
- /* Guard against addr being lower than the first VMA */
- vma = mm->mmap;
-
- /* Go through the RB tree quickly. */
- rb_node = mm->mm_rb.rb_node;
-
- while (rb_node) {
- struct vm_area_struct *vma_tmp;
- vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
-
- if (addr < vma_tmp->vm_end) {
- rb_node = rb_node->rb_left;
- } else {
- prev = vma_tmp;
- if (!prev->vm_next || (addr < prev->vm_next->vm_end))
- break;
- rb_node = rb_node->rb_right;
- }
- }
+ struct vm_area_struct *vma;
-out:
- *pprev = prev;
- return prev ? prev->vm_next : vma;
+ vma = find_vma(mm, addr);
+ *pprev = vma ? vma->vm_prev : NULL;
+ return vma;
}
/*
@@ -2322,13 +2302,16 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
struct vm_area_struct *new_vma, *prev;
struct rb_node **rb_link, *rb_parent;
struct mempolicy *pol;
+ bool faulted_in_anon_vma = true;
/*
* If anonymous vma has not yet been faulted, update new pgoff
* to match new location, to increase its chance of merging.
*/
- if (!vma->vm_file && !vma->anon_vma)
+ if (unlikely(!vma->vm_file && !vma->anon_vma)) {
pgoff = addr >> PAGE_SHIFT;
+ faulted_in_anon_vma = false;
+ }
find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
@@ -2337,9 +2320,24 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
/*
* Source vma may have been merged into new_vma
*/
- if (vma_start >= new_vma->vm_start &&
- vma_start < new_vma->vm_end)
+ if (unlikely(vma_start >= new_vma->vm_start &&
+ vma_start < new_vma->vm_end)) {
+ /*
+ * The only way we can get a vma_merge with
+ * self during an mremap is if the vma hasn't
+ * been faulted in yet and we were allowed to
+ * reset the dst vma->vm_pgoff to the
+ * destination address of the mremap to allow
+ * the merge to happen. mremap must change the
+ * vm_pgoff linearity between src and dst vmas
+ * (in turn preventing a vma_merge) to be
+ * safe. It is only safe to keep the vm_pgoff
+ * linear if there are no pages mapped yet.
+ */
+ VM_BUG_ON(faulted_in_anon_vma);
*vmap = new_vma;
+ } else
+ anon_vma_moveto_tail(new_vma);
} else {
new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
if (new_vma) {