Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423574Ab2KNX2S (ORCPT ); Wed, 14 Nov 2012 18:28:18 -0500 Received: from mail-pa0-f46.google.com ([209.85.220.46]:43343 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423519Ab2KNX2R (ORCPT ); Wed, 14 Nov 2012 18:28:17 -0500 Date: Wed, 14 Nov 2012 15:28:15 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: "Kirill A. Shutemov" cc: Andrew Morton , Andrea Arcangeli , linux-mm@kvack.org, Andi Kleen , "H. Peter Anvin" , linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: Re: [PATCH v5 07/11] thp: implement splitting pmd for huge zero page In-Reply-To: <1352300463-12627-8-git-send-email-kirill.shutemov@linux.intel.com> Message-ID: References: <1352300463-12627-1-git-send-email-kirill.shutemov@linux.intel.com> <1352300463-12627-8-git-send-email-kirill.shutemov@linux.intel.com> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3204 Lines: 96 On Wed, 7 Nov 2012, Kirill A. Shutemov wrote: > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 90e651c..f36bc7d 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -1611,6 +1611,7 @@ 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) > @@ -2509,23 +2510,63 @@ 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) > +{ This entire function duplicates other code in mm/huge_memory.c which gives even more incentive into breaking do_huge_pmd_wp_zero_page_fallback() into logical helper functions and reusing them for both page and !page. Duplicating all this code throughout the thp code just becomes a maintenance nightmare down the road. > + pgtable_t pgtable; > + pmd_t _pmd; > + int i; > + > + pmdp_clear_flush(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) > { > struct page *page; > + struct mm_struct *mm = vma->vm_mm; > unsigned long haddr = address & HPAGE_PMD_MASK; > + unsigned long mmun_start; /* For mmu_notifiers */ > + unsigned long mmun_end; /* For mmu_notifiers */ > > BUG_ON(vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE); > > - spin_lock(&vma->vm_mm->page_table_lock); > + mmun_start = haddr; > + mmun_end = address + HPAGE_PMD_SIZE; address or haddr? > + mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); > + spin_lock(&mm->page_table_lock); > if (unlikely(!pmd_trans_huge(*pmd))) { > - spin_unlock(&vma->vm_mm->page_table_lock); > + spin_unlock(&mm->page_table_lock); > + mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); > + return; > + } > + if (is_huge_zero_pmd(*pmd)) { > + __split_huge_zero_page_pmd(vma, haddr, pmd); > + spin_unlock(&mm->page_table_lock); > + mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); > return; > } > page = pmd_page(*pmd); > VM_BUG_ON(!page_count(page)); > get_page(page); > - spin_unlock(&vma->vm_mm->page_table_lock); > + spin_unlock(&mm->page_table_lock); > + mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); > > split_huge_page(page); > -- 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/