Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751711Ab2JANw0 (ORCPT ); Mon, 1 Oct 2012 09:52:26 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:35542 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750863Ab2JANwY (ORCPT ); Mon, 1 Oct 2012 09:52:24 -0400 From: Will Deacon To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, akpm@linux-foundation.org, mhocko@suse.cz, Steve Capper , Andrea Arcangeli , Chris Metcalf , Will Deacon Subject: [PATCH] mm: thp: Set the accessed flag for old pages on access fault. Date: Mon, 1 Oct 2012 14:51:45 +0100 Message-Id: <1349099505-5581-1-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: 3125 Lines: 93 From: Steve Capper 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: Andrea Arcangeli Cc: Chris Metcalf Signed-off-by: Steve Capper Signed-off-by: Will Deacon --- Hello again, This is another fix for an issue that we discovered when porting THP to ARM but it somehow managed to slip through the cracks. Will include/linux/huge_mm.h | 3 +++ mm/huge_memory.c | 12 ++++++++++++ mm/memory.c | 4 ++++ 3 files changed, 19 insertions(+), 0 deletions(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 4c59b11..bbc62ad 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -8,6 +8,9 @@ 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); 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 d684934..ee9cc3b 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -914,6 +914,18 @@ out_free_pages: goto out; } +void huge_pmd_set_accessed(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long address, pmd_t *pmd, pmd_t orig_pmd) +{ + pmd_t entry; + + spin_lock(&mm->page_table_lock); + entry = pmd_mkyoung(orig_pmd); + if (pmdp_set_access_flags(vma, address & HPAGE_PMD_MASK, pmd, entry, 0)) + update_mmu_cache(vma, address, pmd); + spin_unlock(&mm->page_table_lock); +} + 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/memory.c b/mm/memory.c index 5736170..d5c007d 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3537,7 +3537,11 @@ retry: if (unlikely(ret & VM_FAULT_OOM)) goto retry; return ret; + } else { + huge_pmd_set_accessed(mm, vma, address, pmd, + orig_pmd); } + return 0; } } -- 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/