diff options
| author | Andrea Arcangeli <aarcange@redhat.com> | 2011-01-13 15:47:20 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-01-13 17:32:48 -0800 |
| commit | 22e5c47ee238abe636655c3862ed28d6eb084ad4 (patch) | |
| tree | 4a4e7d330cbef6c99a8914de482eb0e8daba2485 /include/linux/huge_mm.h | |
| parent | 29ad768cfc08611a4c1070d0f13f82eeea2bac7b (diff) | |
thp: add compound_trans_head() helper
Cleanup some code with common compound_trans_head helper.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Avi Kivity <avi@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/huge_mm.h')
| -rw-r--r-- | include/linux/huge_mm.h | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index bddfba1d7b85..8e6c8c42bc3c 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -126,6 +126,23 @@ static inline int hpage_nr_pages(struct page *page) return HPAGE_PMD_NR; return 1; } +static inline struct page *compound_trans_head(struct page *page) +{ + if (PageTail(page)) { + struct page *head; + head = page->first_page; + smp_rmb(); + /* + * head may be a dangling pointer. + * __split_huge_page_refcount clears PageTail before + * overwriting first_page, so if PageTail is still + * there it means the head pointer isn't dangling. + */ + if (PageTail(page)) + return head; + } + return page; +} #else /* CONFIG_TRANSPARENT_HUGEPAGE */ #define HPAGE_PMD_SHIFT ({ BUG(); 0; }) #define HPAGE_PMD_MASK ({ BUG(); 0; }) @@ -144,6 +161,7 @@ static inline int split_huge_page(struct page *page) do { } while (0) #define wait_split_huge_page(__anon_vma, __pmd) \ do { } while (0) +#define compound_trans_head(page) compound_head(page) static inline int hugepage_madvise(struct vm_area_struct *vma, unsigned long *vm_flags, int advice) { |