diff options
| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2016-07-27 00:25:53 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-07-27 01:19:19 +0200 |
| commit | 9a73f61bdb8acdc01bbaf72a3fe0a8854f2463ad (patch) | |
| tree | add475877423bc5ae648e67d221324ceaa388fcf /mm/rmap.c | |
| parent | thp: file pages support for split_huge_page() (diff) | |
| download | linux-9a73f61bdb8acdc01bbaf72a3fe0a8854f2463ad.tar.xz linux-9a73f61bdb8acdc01bbaf72a3fe0a8854f2463ad.zip | |
thp, mlock: do not mlock PTE-mapped file huge pages
As with anon THP, we only mlock file huge pages if we can prove that the
page is not mapped with PTE. This way we can avoid mlock leak into
non-mlocked vma on split.
We rely on PageDoubleMap() under lock_page() to check if the the page
may be PTE mapped. PG_double_map is set by page_add_file_rmap() when
the page mapped with PTEs.
Link: http://lkml.kernel.org/r/1466021202-61880-21-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 2b336c4277da..9d643b7a99ce 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1284,6 +1284,12 @@ void page_add_file_rmap(struct page *page, bool compound) if (!atomic_inc_and_test(compound_mapcount_ptr(page))) goto out; } else { + if (PageTransCompound(page)) { + VM_BUG_ON_PAGE(!PageLocked(page), page); + SetPageDoubleMap(compound_head(page)); + if (PageMlocked(page)) + clear_page_mlock(compound_head(page)); + } if (!atomic_inc_and_test(&page->_mapcount)) goto out; } @@ -1458,8 +1464,14 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, */ if (!(flags & TTU_IGNORE_MLOCK)) { if (vma->vm_flags & VM_LOCKED) { - /* Holding pte lock, we do *not* need mmap_sem here */ - mlock_vma_page(page); + /* PTE-mapped THP are never mlocked */ + if (!PageTransCompound(page)) { + /* + * Holding pte lock, we do *not* need + * mmap_sem here + */ + mlock_vma_page(page); + } ret = SWAP_MLOCK; goto out_unmap; } |