From: Andrea Arcangeli <aarcange@xxxxxxxxxx> Subject: mm: thp: microoptimize compound_mapcount() compound_mapcount() is only called after PageCompound() has already been checked by the caller, so there's no point to check it again. Gcc may optimize it away too because it's inline but this will remove the runtime check for sure and add it'll add an assert instead. Link: http://lkml.kernel.org/r/1462547040-1737-3-git-send-email-aarcange@xxxxxxxxxx Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx> Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: Alex Williamson <alex.williamson@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/mm.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff -puN include/linux/mm.h~mm-thp-microoptimize-compound_mapcount include/linux/mm.h --- a/include/linux/mm.h~mm-thp-microoptimize-compound_mapcount +++ a/include/linux/mm.h @@ -475,8 +475,7 @@ static inline atomic_t *compound_mapcoun static inline int compound_mapcount(struct page *page) { - if (!PageCompound(page)) - return 0; + VM_BUG_ON_PAGE(!PageCompound(page), page); page = compound_head(page); return atomic_read(compound_mapcount_ptr(page)) + 1; } _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
