From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx199.postini.com [74.125.245.199]) by kanga.kvack.org (Postfix) with SMTP id E16326B0031 for ; Mon, 17 Jun 2013 18:03:09 -0400 (EDT) From: "Kirill A. Shutemov" Subject: [PATCH] thp: define HPAGE_PMD_* constans as BUILD_BUG() if !THP Date: Tue, 18 Jun 2013 01:05:40 +0300 Message-Id: <1371506740-14606-1-git-send-email-kirill.shutemov@linux.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton , "Aneesh Kumar K.V" Cc: Andrea Arcangeli , linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Kirill A. Shutemov" From: "Kirill A. Shutemov" Currently, HPAGE_PMD_* constans rely on PMD_SHIFT regardless of CONFIG_TRANSPARENT_HUGEPAGE. PMD_SHIFT is not defined everywhere (e.g. arm nommu case). It means we can't use anything like this in generic code: if (PageTransHuge(page)) zero_huge_user(page, 0, HPAGE_PMD_SIZE); else clear_highpage(page); For !THP case, PageTransHuge() is 0 and compiler can eliminate zero_huge_user() call. But it still need to be valid C expression, means HPAGE_PMD_SIZE has to expand to something compiler can understand. Previously, HPAGE_PMD_* were defined to BUILD_BUG() for !THP. Let's come back to it. Signed-off-by: Kirill A. Shutemov --- include/linux/huge_mm.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index cc276d2..e2dbefb 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -58,11 +58,12 @@ extern pmd_t *page_check_address_pmd(struct page *page, #define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT) #define HPAGE_PMD_NR (1< email@kvack.org