Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752603AbdFPLbo (ORCPT ); Fri, 16 Jun 2017 07:31:44 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:51259 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751677AbdFPLbn (ORCPT ); Fri, 16 Jun 2017 07:31:43 -0400 From: "Aneesh Kumar K.V" To: "Kirill A. Shutemov" , Andrew Morton , Vlastimil Babka , Vineet Gupta , Russell King , Will Deacon , Catalin Marinas , Ralf Baechle , "David S. Miller" , Martin Schwidefsky , Heiko Carstens , Andrea Arcangeli Cc: linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: Re: [PATCHv2 3/3] mm: Use updated pmdp_invalidate() inteface to track dirty/accessed bits In-Reply-To: <20170615145224.66200-4-kirill.shutemov@linux.intel.com> References: <20170615145224.66200-1-kirill.shutemov@linux.intel.com> <20170615145224.66200-4-kirill.shutemov@linux.intel.com> Date: Fri, 16 Jun 2017 17:01:30 +0530 MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-MML: disable x-cbid: 17061611-0052-0000-0000-00000257B445 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17061611-0053-0000-0000-0000083612CE Message-Id: <87bmpob23x.fsf@skywalker.in.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-06-16_06:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1706160186 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1872 Lines: 59 "Kirill A. Shutemov" writes: > This patch uses modifed pmdp_invalidate(), that return previous value of pmd, > to transfer dirty and accessed bits. > > Signed-off-by: Kirill A. Shutemov > --- > fs/proc/task_mmu.c | 8 ++++---- > mm/huge_memory.c | 29 ++++++++++++----------------- > 2 files changed, 16 insertions(+), 21 deletions(-) > > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c > index f0c8b33d99b1..f2fc1ef5bba2 100644 > --- a/fs/proc/task_mmu.c > +++ b/fs/proc/task_mmu.c ..... > @@ -1965,7 +1955,6 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, > page_ref_add(page, HPAGE_PMD_NR - 1); > write = pmd_write(*pmd); > young = pmd_young(*pmd); > - dirty = pmd_dirty(*pmd); > soft_dirty = pmd_soft_dirty(*pmd); > > pmdp_huge_split_prepare(vma, haddr, pmd); > @@ -1995,8 +1984,6 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, > if (soft_dirty) > entry = pte_mksoft_dirty(entry); > } > - if (dirty) > - SetPageDirty(page + i); > pte = pte_offset_map(&_pmd, addr); > BUG_ON(!pte_none(*pte)); > set_pte_at(mm, addr, pte, entry); > @@ -2045,7 +2032,15 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, > * and finally we write the non-huge version of the pmd entry with > * pmd_populate. > */ > - pmdp_invalidate(vma, haddr, pmd); > + old = pmdp_invalidate(vma, haddr, pmd); > + > + /* > + * Transfer dirty bit using value returned by pmd_invalidate() to be > + * sure we don't race with CPU that can set the bit under us. > + */ > + if (pmd_dirty(old)) > + SetPageDirty(page); > + > pmd_populate(mm, pmd, pgtable); > > if (freeze) { Can we invalidate the pmd early here ? ie, do pmdp_invalidate instead of pmdp_huge_split_prepare() ? -aneesh