diff options
| author | Andrew Morton <[email protected]> | 2014-12-18 16:17:29 -0800 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2014-12-18 19:08:11 -0800 |
| commit | d82fa87d2b60e8affea3b244ad23c5d9a59c584a (patch) | |
| tree | e989c53dc22e9adc967880171c805df3a85048aa | |
| parent | 48332f28461c72af4b98611e0b4f02d769b8cc70 (diff) | |
mm/memory.c:do_shared_fault(): add comment
Belatedly document the changes in commit f0c6d4d295e4 ("mm: introduce
do_shared_fault() and drop do_fault()").
Cc: Andi Kleen <[email protected]>
Cc: Bob Liu <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Sasha Levin <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
| -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) { |