From: Christoffer Dall <[email protected]> Unfortunately with !CONFIG_PAGEFLAGS_EXTENDED, (!PageHead) is false, and (PageHead) is true, for tail pages. This breaks cache cleaning on some ARM systems, and may cause other bugs.
This patch makes sure PageHead is only true for head pages and PageTail is only true for tail pages, and neither is true for non-compound pages. Cc: Steve Capper <[email protected]> Cc: Will Deacon <[email protected]> Cc: Andrea Arcangeli <[email protected]> Cc: Linus Torvalds <[email protected]> Acked-by: Christoph Lameter <[email protected]> Signed-off-by: Christoffer Dall <[email protected]> --- include/linux/page-flags.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index b5d1384..70473da 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -362,7 +362,7 @@ static inline void ClearPageCompound(struct page *page) * pages on the LRU and/or pagecache. */ TESTPAGEFLAG(Compound, compound) -__PAGEFLAG(Head, compound) +__SETPAGEFLAG(Head, compound) __CLEARPAGEFLAG(Head, compound) /* * PG_reclaim is used in combination with PG_compound to mark the @@ -374,8 +374,14 @@ __PAGEFLAG(Head, compound) * PG_compound & PG_reclaim => Tail page * PG_compound & ~PG_reclaim => Head page */ +#define PG_head_mask ((1L << PG_compound)) #define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim)) +static inline int PageHead(struct page *page) +{ + return ((page->flags & PG_head_tail_mask) == PG_head_mask); +} + static inline int PageTail(struct page *page) { return ((page->flags & PG_head_tail_mask) == PG_head_tail_mask); -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
