vma = find_vma_prev(mm, addr, &prev);
if (vma && (vma->vm_start <= addr))
return vma;
- if (expand_stack(prev, addr))
+ if (!prev || expand_stack(prev, addr))
return NULL;
if (prev->vm_flags & VM_LOCKED) {
if (mlock_vma_pages_range(prev, addr, prev->vm_end) < 0)