From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932767AbcBIQMD (ORCPT ); Tue, 9 Feb 2016 11:12:03 -0500 Received: from e35.co.us.ibm.com ([32.97.110.153]:38401 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932710AbcBIQL7 (ORCPT ); Tue, 9 Feb 2016 11:11:59 -0500 X-IBM-Helo: d03dlp01.boulder.ibm.com X-IBM-MailFrom: aneesh.kumar@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org From: "Aneesh Kumar K.V" To: akpm@linux-foundation.org, mpe@ellerman.id.au, "Kirill A. Shutemov" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Aneesh Kumar K.V" Subject: [PATCH V2] mm: Some arch may want to use HPAGE_PMD related values as variables Date: Tue, 9 Feb 2016 21:41:44 +0530 Message-Id: <1455034304-15301-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> X-Mailer: git-send-email 2.5.0 X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16020916-0013-0000-0000-00001CAD9A99 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org With next generation power processor, we are having a new mmu model [1] that require us to maintain a different linux page table format. Inorder to support both current and future ppc64 systems with a single kernel we need to make sure kernel can select between different page table format at runtime. With the new MMU (radix MMU) added, we will have two different pmd hugepage size 16MB for hash model and 2MB for Radix model. Hence make HPAGE_PMD related values as a variable. [1] http://ibm.biz/power-isa3 (Needs registration). Signed-off-by: Aneesh Kumar K.V --- arch/powerpc/mm/pgtable_64.c | 7 +++++++ include/linux/bug.h | 9 +++++++++ include/linux/huge_mm.h | 3 --- mm/huge_memory.c | 17 ++++++++++++++--- 4 files changed, 30 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c index c8a00da39969..80dd8e0d8322 100644 --- a/arch/powerpc/mm/pgtable_64.c +++ b/arch/powerpc/mm/pgtable_64.c @@ -818,6 +818,13 @@ pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm, int has_transparent_hugepage(void) { + + BUILD_BUG_ON_MSG((PMD_SHIFT - PAGE_SHIFT) >= MAX_ORDER, + "hugepages can't be allocated by the buddy allocator"); + + BUILD_BUG_ON_MSG((PMD_SHIFT - PAGE_SHIFT) < 2, + "We need more than 2 pages to do deferred thp split"); + if (!mmu_has_feature(MMU_FTR_16M_PAGE)) return 0; /* diff --git a/include/linux/bug.h b/include/linux/bug.h index 7f4818673c41..e51b0709e78d 100644 --- a/include/linux/bug.h +++ b/include/linux/bug.h @@ -20,6 +20,7 @@ struct pt_regs; #define BUILD_BUG_ON_MSG(cond, msg) (0) #define BUILD_BUG_ON(condition) (0) #define BUILD_BUG() (0) +#define MAYBE_BUILD_BUG_ON(cond) (0) #else /* __CHECKER__ */ /* Force a compilation error if a constant expression is not a power of 2 */ @@ -83,6 +84,14 @@ struct pt_regs; */ #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed") +#define MAYBE_BUILD_BUG_ON(cond) \ + do { \ + if (__builtin_constant_p((cond))) \ + BUILD_BUG_ON(cond); \ + else \ + BUG_ON(cond); \ + } while (0) + #endif /* __CHECKER__ */ #ifdef CONFIG_GENERIC_BUG diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 459fd25b378e..f12513a20a06 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -111,9 +111,6 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, __split_huge_pmd(__vma, __pmd, __address); \ } while (0) -#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, unsigned long *vm_flags, int advice); extern void vma_adjust_trans_huge(struct vm_area_struct *vma, diff --git a/mm/huge_memory.c b/mm/huge_memory.c index cd26f3f14cab..350410e9019e 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -83,7 +83,7 @@ unsigned long transparent_hugepage_flags __read_mostly = (1<= MAX_ORDER); + /* + * we use page->mapping and page->index in second tail page + * as list_head: assuming THP order >= 2 + */ + MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); + err = hugepage_init_sysfs(&hugepage_kobj); if (err) goto err_sysfs; @@ -764,7 +776,6 @@ void prep_transhuge_page(struct page *page) * we use page->mapping and page->indexlru in second tail page * as list_head: assuming THP order >= 2 */ - BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); INIT_LIST_HEAD(page_deferred_list(page)); set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); -- 2.5.0