Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966988AbaFTUM0 (ORCPT ); Fri, 20 Jun 2014 16:12:26 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49306 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966661AbaFTUMS (ORCPT ); Fri, 20 Jun 2014 16:12:18 -0400 From: Naoya Horiguchi To: linux-mm@kvack.org Cc: Andrew Morton , Dave Hansen , Hugh Dickins , "Kirill A. Shutemov" , linux-kernel@vger.kernel.org, Naoya Horiguchi , "Kirill A. Shutemov" , Pavel Emelyanov , Andrea Arcangeli , Cyrill Gorcunov Subject: [PATCH v3 12/13] mm: /proc/pid/clear_refs: avoid split_huge_page() Date: Fri, 20 Jun 2014 16:11:38 -0400 Message-Id: <1403295099-6407-13-git-send-email-n-horiguchi@ah.jp.nec.com> In-Reply-To: <1403295099-6407-1-git-send-email-n-horiguchi@ah.jp.nec.com> References: <1403295099-6407-1-git-send-email-n-horiguchi@ah.jp.nec.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Kirill A. Shutemov" Currently pagewalker splits all THP pages on any clear_refs request. It's not necessary. We can handle this on PMD level. One side effect is that soft dirty will potentially see more dirty memory, since we will mark whole THP page dirty at once. Sanity checked with CRIU test suite. More testing is required. ChangeLog: - move code for thp to clear_refs_pte_range() Signed-off-by: Kirill A. Shutemov Cc: Pavel Emelyanov Cc: Andrea Arcangeli Cc: Dave Hansen Signed-off-by: Naoya Horiguchi Cc: Cyrill Gorcunov Signed-off-by: Andrew Morton --- fs/proc/task_mmu.c | 47 ++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 44 insertions(+), 3 deletions(-) diff --git v3.16-rc1.orig/fs/proc/task_mmu.c v3.16-rc1/fs/proc/task_mmu.c index ac50a829320a..2acbe144152c 100644 --- v3.16-rc1.orig/fs/proc/task_mmu.c +++ v3.16-rc1/fs/proc/task_mmu.c @@ -719,10 +719,10 @@ struct clear_refs_private { enum clear_refs_types type; }; +#ifdef CONFIG_MEM_SOFT_DIRTY static inline void clear_soft_dirty(struct vm_area_struct *vma, unsigned long addr, pte_t *pte) { -#ifdef CONFIG_MEM_SOFT_DIRTY /* * The soft-dirty tracker uses #PF-s to catch writes * to pages, so write-protect the pte as well. See the @@ -741,9 +741,35 @@ static inline void clear_soft_dirty(struct vm_area_struct *vma, } set_pte_at(vma->vm_mm, addr, pte, ptent); -#endif } +static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma, + unsigned long addr, pmd_t *pmdp) +{ + pmd_t pmd = *pmdp; + + pmd = pmd_wrprotect(pmd); + pmd = pmd_clear_flags(pmd, _PAGE_SOFT_DIRTY); + + if (vma->vm_flags & VM_SOFTDIRTY) + vma->vm_flags &= ~VM_SOFTDIRTY; + + set_pmd_at(vma->vm_mm, addr, pmdp, pmd); +} + +#else + +static inline void clear_soft_dirty(struct vm_area_struct *vma, + unsigned long addr, pte_t *pte) +{ +} + +static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma, + unsigned long addr, pmd_t *pmdp) +{ +} +#endif + static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, struct mm_walk *walk) { @@ -753,7 +779,22 @@ static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr, spinlock_t *ptl; struct page *page; - split_huge_page_pmd(vma, addr, pmd); + if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) { + if (cp->type == CLEAR_REFS_SOFT_DIRTY) { + clear_soft_dirty_pmd(vma, addr, pmd); + goto out; + } + + page = pmd_page(*pmd); + + /* Clear accessed and referenced bits. */ + pmdp_test_and_clear_young(vma, addr, pmd); + ClearPageReferenced(page); +out: + spin_unlock(ptl); + return 0; + } + if (pmd_trans_unstable(pmd)) return 0; -- 1.9.3 -- 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/