Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946218Ab2JYQpS (ORCPT ); Thu, 25 Oct 2012 12:45:18 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:44943 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755502Ab2JYQpQ (ORCPT ); Thu, 25 Oct 2012 12:45:16 -0400 From: Will Deacon To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, mhocko@suse.cz, peterz@infradead.org, akpm@linux-foundation.org, Will Deacon , Chris Metcalf , "Kirill A. Shutemov" , Andrea Arcangeli Subject: [PATCH v3] mm: thp: Set the accessed flag for old pages on access fault. Date: Thu, 25 Oct 2012 17:44:31 +0100 Message-Id: <1351183471-14710-1-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 1.7.4.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3934 Lines: 119 On x86 memory accesses to pages without the ACCESSED flag set result in the ACCESSED flag being set automatically. With the ARM architecture a page access fault is raised instead (and it will continue to be raised until the ACCESSED flag is set for the appropriate PTE/PMD). For normal memory pages, handle_pte_fault will call pte_mkyoung (effectively setting the ACCESSED flag). For transparent huge pages, pmd_mkyoung will only be called for a write fault. This patch ensures that faults on transparent hugepages which do not result in a CoW update the access flags for the faulting pmd. Cc: Chris Metcalf Cc: Kirill A. Shutemov Cc: Andrea Arcangeli Signed-off-by: Will Deacon --- Ok chaps, I rebased this thing onto today's next (which basically necessitated a rewrite) so I've reluctantly dropped my acks and kindly ask if you could eyeball the new code, especially where the locking is concerned. In the numa code (do_huge_pmd_prot_none), Peter checks again that the page is not splitting, but I can't see why that is required. Cheers, Will include/linux/huge_mm.h | 4 ++++ mm/huge_memory.c | 22 ++++++++++++++++++++++ mm/memory.c | 7 ++++++- 3 files changed, 32 insertions(+), 1 deletions(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 4f0f948..766fb27 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -8,6 +8,10 @@ extern int do_huge_pmd_anonymous_page(struct mm_struct *mm, extern int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, struct vm_area_struct *vma); +extern void huge_pmd_set_accessed(struct mm_struct *mm, + struct vm_area_struct *vma, + unsigned long address, pmd_t *pmd, + pmd_t orig_pmd, int dirty); extern int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, pmd_t *pmd, pmd_t orig_pmd); diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 3c14a96..f024d98 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -932,6 +932,28 @@ out: return ret; } +void huge_pmd_set_accessed(struct mm_struct *mm, + struct vm_area_struct *vma, + unsigned long address, + pmd_t *pmd, pmd_t orig_pmd, + int dirty) +{ + pmd_t entry; + unsigned long haddr; + + spin_lock(&mm->page_table_lock); + if (unlikely(!pmd_same(*pmd, orig_pmd))) + goto unlock; + + entry = pmd_mkyoung(orig_pmd); + haddr = address & HPAGE_PMD_MASK; + if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty)) + update_mmu_cache_pmd(vma, address, pmd); + +unlock: + spin_unlock(&mm->page_table_lock); +} + static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, diff --git a/mm/memory.c b/mm/memory.c index f21ac1c..bcbc084 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3650,12 +3650,14 @@ retry: barrier(); if (pmd_trans_huge(orig_pmd) && !pmd_trans_splitting(orig_pmd)) { + unsigned int dirty = flags & FAULT_FLAG_WRITE; + if (pmd_numa(vma, orig_pmd)) { do_huge_pmd_numa_page(mm, vma, address, pmd, flags, orig_pmd); } - if ((flags & FAULT_FLAG_WRITE) && !pmd_write(orig_pmd)) { + if (dirty && !pmd_write(orig_pmd)) { ret = do_huge_pmd_wp_page(mm, vma, address, pmd, orig_pmd); /* @@ -3665,6 +3667,9 @@ retry: */ if (unlikely(ret & VM_FAULT_OOM)) goto retry; + } else { + huge_pmd_set_accessed(mm, vma, address, pmd, + orig_pmd, dirty); } return ret; -- 1.7.4.1 -- 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/