mm: thp: Correct the HPAGE_PMD_ORDER check.

All Transparent Huge Pages are allocated by the buddy allocator.

A compile time check is in place that fails when the order of a
transparent huge page is too large to be allocated by the buddy
allocator. Unfortunately that compile time check passes when:
HPAGE_PMD_ORDER == MAX_ORDER
( which is incorrect as the buddy allocator can only allocate
memory of order strictly less than MAX_ORDER. )

This patch updates the compile time check to fail in the above
case.

Signed-off-by: Steve Capper <steve.capper@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 528454c2caa91b17cbb5761de006418909de2046..26ee56c80dc7c525d15e664bcc1a3f2dd3fdd221 100644 (file)
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -123,7 +123,7 @@ extern void __split_huge_page_pmd(struct vm_area_struct *vma,
        } while (0)
 extern void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address,
                pmd_t *pmd);
-#if HPAGE_PMD_ORDER > MAX_ORDER
+#if HPAGE_PMD_ORDER >= MAX_ORDER
 #error "hugepages can't be allocated by the buddy allocator"
 #endif
 extern int hugepage_madvise(struct vm_area_struct *vma,