Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754535Ab2JBPTZ (ORCPT ); Tue, 2 Oct 2012 11:19:25 -0400 Received: from mga01.intel.com ([192.55.52.88]:14204 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754281Ab2JBPTB (ORCPT ); Tue, 2 Oct 2012 11:19:01 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.80,524,1344236400"; d="scan'208";a="229573192" From: "Kirill A. Shutemov" To: Andrew Morton , linux-mm@kvack.org Cc: Andrea Arcangeli , Andi Kleen , "H. Peter Anvin" , linux-kernel@vger.kernel.org, "Kirill A. Shutemov" , "Kirill A. Shutemov" Subject: [PATCH v3 07/10] thp: implement splitting pmd for huge zero page Date: Tue, 2 Oct 2012 18:19:29 +0300 Message-Id: <1349191172-28855-8-git-send-email-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1349191172-28855-1-git-send-email-kirill.shutemov@linux.intel.com> References: <1349191172-28855-1-git-send-email-kirill.shutemov@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2365 Lines: 79 From: "Kirill A. Shutemov" We can't split huge zero page itself, but we can split the pmd which points to it. On splitting the pmd we create a table with all ptes set to normal zero page. Signed-off-by: Kirill A. Shutemov Reviewed-by: Andrea Arcangeli --- mm/huge_memory.c | 32 ++++++++++++++++++++++++++++++++ 1 files changed, 32 insertions(+), 0 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 95032d3..3f1c59c 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1600,6 +1600,7 @@ int split_huge_page(struct page *page) struct anon_vma *anon_vma; int ret = 1; + BUG_ON(is_huge_zero_pfn(page_to_pfn(page))); BUG_ON(!PageAnon(page)); anon_vma = page_lock_anon_vma(page); if (!anon_vma) @@ -2503,6 +2504,32 @@ static int khugepaged(void *none) return 0; } +static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, + unsigned long haddr, pmd_t *pmd) +{ + pgtable_t pgtable; + pmd_t _pmd; + int i; + + pmdp_clear_flush_notify(vma, haddr, pmd); + /* leave pmd empty until pte is filled */ + + pgtable = get_pmd_huge_pte(vma->vm_mm); + pmd_populate(vma->vm_mm, &_pmd, pgtable); + + for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { + pte_t *pte, entry; + entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); + entry = pte_mkspecial(entry); + pte = pte_offset_map(&_pmd, haddr); + VM_BUG_ON(!pte_none(*pte)); + set_pte_at(vma->vm_mm, haddr, pte, entry); + pte_unmap(pte); + } + smp_wmb(); /* make pte visible before pmd */ + pmd_populate(vma->vm_mm, pmd, pgtable); +} + void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address, pmd_t *pmd) { @@ -2516,6 +2543,11 @@ void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address, spin_unlock(&vma->vm_mm->page_table_lock); return; } + if (is_huge_zero_pmd(*pmd)) { + __split_huge_zero_page_pmd(vma, haddr, pmd); + spin_unlock(&vma->vm_mm->page_table_lock); + return; + } page = pmd_page(*pmd); VM_BUG_ON(!page_count(page)); get_page(page); -- 1.7.7.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/