Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161087AbbKEJK4 (ORCPT ); Thu, 5 Nov 2015 04:10:56 -0500 Received: from relay.parallels.com ([195.214.232.42]:55893 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031213AbbKEJKe (ORCPT ); Thu, 5 Nov 2015 04:10:34 -0500 Date: Thu, 5 Nov 2015 12:10:13 +0300 From: Vladimir Davydov To: "Kirill A. Shutemov" CC: Andrew Morton , Andrea Arcangeli , Hugh Dickins , Naoya Horiguchi , Sasha Levin , Minchan Kim , , Subject: Re: [PATCH 4/4] mm: prepare page_referenced() and page_idle to new THP refcounting Message-ID: <20151105091013.GC29259@esperanza> References: <1446564375-72143-1-git-send-email-kirill.shutemov@linux.intel.com> <1446564375-72143-5-git-send-email-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <1446564375-72143-5-git-send-email-kirill.shutemov@linux.intel.com> X-ClientProxiedBy: US-EXCH2.sw.swsoft.com (10.255.249.46) To MSK-EXCH1.sw.swsoft.com (10.67.48.55) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2474 Lines: 90 On Tue, Nov 03, 2015 at 05:26:15PM +0200, Kirill A. Shutemov wrote: ... > @@ -56,23 +56,69 @@ static int page_idle_clear_pte_refs_one(struct page *page, > { > struct mm_struct *mm = vma->vm_mm; > spinlock_t *ptl; > + pgd_t *pgd; > + pud_t *pud; > pmd_t *pmd; > pte_t *pte; > bool referenced = false; > > - if (unlikely(PageTransHuge(page))) { > - pmd = page_check_address_pmd(page, mm, addr, &ptl); > - if (pmd) { > - referenced = pmdp_clear_young_notify(vma, addr, pmd); > + pgd = pgd_offset(mm, addr); > + if (!pgd_present(*pgd)) > + return SWAP_AGAIN; > + pud = pud_offset(pgd, addr); > + if (!pud_present(*pud)) > + return SWAP_AGAIN; > + pmd = pmd_offset(pud, addr); > + > + if (pmd_trans_huge(*pmd)) { > + ptl = pmd_lock(mm, pmd); > + if (!pmd_present(*pmd)) > + goto unlock_pmd; > + if (unlikely(!pmd_trans_huge(*pmd))) { > spin_unlock(ptl); > + goto map_pte; > } > + > + if (pmd_page(*pmd) != page) > + goto unlock_pmd; > + > + referenced = pmdp_clear_young_notify(vma, addr, pmd); > + spin_unlock(ptl); > + goto found; > +unlock_pmd: > + spin_unlock(ptl); > + return SWAP_AGAIN; > } else { > - pte = page_check_address(page, mm, addr, &ptl, 0); > - if (pte) { > - referenced = ptep_clear_young_notify(vma, addr, pte); > - pte_unmap_unlock(pte, ptl); > - } > + pmd_t pmde = *pmd; > + barrier(); > + if (!pmd_present(pmde) || pmd_trans_huge(pmde)) > + return SWAP_AGAIN; > + > + } > +map_pte: > + pte = pte_offset_map(pmd, addr); > + if (!pte_present(*pte)) { > + pte_unmap(pte); > + return SWAP_AGAIN; > } > + > + ptl = pte_lockptr(mm, pmd); > + spin_lock(ptl); > + > + if (!pte_present(*pte)) { > + pte_unmap_unlock(pte, ptl); > + return SWAP_AGAIN; > + } > + > + /* THP can be referenced by any subpage */ > + if (pte_pfn(*pte) - page_to_pfn(page) >= hpage_nr_pages(page)) { > + pte_unmap_unlock(pte, ptl); > + return SWAP_AGAIN; > + } > + > + referenced = ptep_clear_young_notify(vma, addr, pte); > + pte_unmap_unlock(pte, ptl); > +found: Can't we hide this stuff in a helper function, which would be used by both page_referenced_one and page_idle_clear_pte_refs_one, instead of duplicating page_referenced_one code here? Thanks, Vladimir -- 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/