From: "Kirill A. Shutemov" <kirill.shute...@linux.intel.com>
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 <kirill.shute...@linux.intel.com>
---
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<<HPAGE_PMD_ORDER)
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
#define HPAGE_PMD_SHIFT PMD_SHIFT
#define HPAGE_PMD_SIZE ((1UL) << HPAGE_PMD_SHIFT)
#define HPAGE_PMD_MASK (~(HPAGE_PMD_SIZE - 1))
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
extern bool is_vma_temporary_stack(struct vm_area_struct *vma);
#define transparent_hugepage_enabled(__vma) \
@@ -180,6 +181,9 @@ extern int do_huge_pmd_numa_page(struct mm_struct *mm,
struct vm_area_struct *vm
unsigned long addr, pmd_t pmd, pmd_t *pmdp);
#else /* CONFIG_TRANSPARENT_HUGEPAGE */
+#define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; })
+#define HPAGE_PMD_MASK ({ BUILD_BUG(); 0; })
+#define HPAGE_PMD_SIZE ({ BUILD_BUG(); 0; })
#define hpage_nr_pages(x) 1
--
1.8.3.1
--
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