Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753167AbbGSLDc (ORCPT ); Sun, 19 Jul 2015 07:03:32 -0400 Received: from mta-out1.inet.fi ([62.71.2.230]:48913 "EHLO johanna2.inet.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752610AbbGSLDb (ORCPT ); Sun, 19 Jul 2015 07:03:31 -0400 RazorGate-KAS: Rate: 5 RazorGate-KAS: {RECEIVED: dynamic ip detected} RazorGate-KAS: Envelope from: RazorGate-KAS: Version: 5.5.3 RazorGate-KAS: LuaCore: 80 2014-11-10_18-01-23 260f8afb9361da3c7edfd3a8e3a4ca908191ad29 RazorGate-KAS: Method: none RazorGate-KAS: Lua profiles 69136 [Nov 12 2014] RazorGate-KAS: Status: not_detected Date: Sun, 19 Jul 2015 14:03:05 +0300 From: "Kirill A. Shutemov" To: Matthew Wilcox Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Matthew Wilcox Subject: Re: [PATCH 03/10] thp: Prepare for DAX huge pages Message-ID: <20150719110305.GA2341@node.dhcp.inet.fi> References: <1436560165-8943-1-git-send-email-matthew.r.wilcox@intel.com> <1436560165-8943-4-git-send-email-matthew.r.wilcox@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1436560165-8943-4-git-send-email-matthew.r.wilcox@intel.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4940 Lines: 154 On Fri, Jul 10, 2015 at 04:29:18PM -0400, Matthew Wilcox wrote: > From: Matthew Wilcox > > Add a vma_is_dax() helper macro to test whether the VMA is DAX, and use > it in zap_huge_pmd() and __split_huge_page_pmd(). > > Signed-off-by: Matthew Wilcox > --- > include/linux/dax.h | 4 ++++ > mm/huge_memory.c | 46 ++++++++++++++++++++++++++++------------------ > 2 files changed, 32 insertions(+), 18 deletions(-) > > diff --git a/include/linux/dax.h b/include/linux/dax.h > index 4f27d3d..9b51f9d 100644 > --- a/include/linux/dax.h > +++ b/include/linux/dax.h > @@ -18,4 +18,8 @@ int dax_pfn_mkwrite(struct vm_area_struct *, struct vm_fault *); > #define dax_mkwrite(vma, vmf, gb, iod) dax_fault(vma, vmf, gb, iod) > #define __dax_mkwrite(vma, vmf, gb, iod) __dax_fault(vma, vmf, gb, iod) > > +static inline bool vma_is_dax(struct vm_area_struct *vma) > +{ > + return vma->vm_file && IS_DAX(vma->vm_file->f_mapping->host); > +} > #endif > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 911071b..b7bd855 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -23,6 +23,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -1391,7 +1392,6 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, > int ret = 0; > > if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) { > - struct page *page; > pgtable_t pgtable; > pmd_t orig_pmd; > /* > @@ -1403,13 +1403,22 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, > orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, > tlb->fullmm); > tlb_remove_pmd_tlb_entry(tlb, pmd, addr); > - pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd); > + if (vma_is_dax(vma)) { > + if (is_huge_zero_pmd(orig_pmd)) { > + pgtable = NULL; pgtable_t is not always a pointer. See arch/arc. > + } else { > + spin_unlock(ptl); > + return 1; > + } > + } else { > + pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd); > + } > if (is_huge_zero_pmd(orig_pmd)) { > atomic_long_dec(&tlb->mm->nr_ptes); > spin_unlock(ptl); > put_huge_zero_page(); > } else { > - page = pmd_page(orig_pmd); > + struct page *page = pmd_page(orig_pmd); > page_remove_rmap(page); > VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); > add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); > @@ -1418,7 +1427,8 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, > spin_unlock(ptl); > tlb_remove_page(tlb, page); > } > - pte_free(tlb->mm, pgtable); > + if (pgtable) > + pte_free(tlb->mm, pgtable); It's better to drop "pgtable = NULL;" above and use "if (vma_is_dax(vma))" here. > ret = 1; > } > return ret; > @@ -2887,7 +2897,7 @@ void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address, > pmd_t *pmd) > { > spinlock_t *ptl; > - struct page *page; > + struct page *page = NULL; > struct mm_struct *mm = vma->vm_mm; > unsigned long haddr = address & HPAGE_PMD_MASK; > unsigned long mmun_start; /* For mmu_notifiers */ > @@ -2900,25 +2910,25 @@ void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address, > again: > mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); > ptl = pmd_lock(mm, pmd); > - if (unlikely(!pmd_trans_huge(*pmd))) { > - spin_unlock(ptl); > - mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); > - return; > - } > - if (is_huge_zero_pmd(*pmd)) { > + if (unlikely(!pmd_trans_huge(*pmd))) > + goto unlock; > + if (vma_is_dax(vma)) { > + pmdp_huge_clear_flush(vma, haddr, pmd); pmdp_huge_clear_flush_notify() > + } else if (is_huge_zero_pmd(*pmd)) { > __split_huge_zero_page_pmd(vma, haddr, pmd); > - spin_unlock(ptl); > - mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); > - return; > + } else { > + page = pmd_page(*pmd); > + VM_BUG_ON_PAGE(!page_count(page), page); > + get_page(page); > } > - page = pmd_page(*pmd); > - VM_BUG_ON_PAGE(!page_count(page), page); > - get_page(page); > + unlock: > spin_unlock(ptl); > mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); > > - split_huge_page(page); > + if (!page) > + return; > > + split_huge_page(page); > put_page(page); > > /* > -- > 2.1.4 > > -- > 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/ -- Kirill A. Shutemov -- 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/