diff options
| -rw-r--r-- | mm/memory.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/mm/memory.c b/mm/memory.c index 6efe36a998ba..d8aebc52265f 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2996,6 +2996,12 @@ static int do_shared_fault(struct mm_struct *mm, struct vm_area_struct *vma, if (set_page_dirty(fault_page)) dirtied = 1; + /* + * Take a local copy of the address_space - page.mapping may be zeroed + * by truncate after unlock_page(). The address_space itself remains + * pinned by vma->vm_file's reference. We rely on unlock_page()'s + * release semantics to prevent the compiler from undoing this copying. + */ mapping = fault_page->mapping; unlock_page(fault_page); if ((dirtied || vma->vm_ops->page_mkwrite) && mapping) { |