From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752669AbbFKJ1d (ORCPT ); Thu, 11 Jun 2015 05:27:33 -0400 Received: from cantor2.suse.de ([195.135.220.15]:59118 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750763AbbFKJ1Y (ORCPT ); Thu, 11 Jun 2015 05:27:24 -0400 Message-ID: <55795477.90808@suse.cz> Date: Thu, 11 Jun 2015 11:27:19 +0200 From: Vlastimil Babka User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: "Kirill A. Shutemov" , Andrew Morton , Andrea Arcangeli , Hugh Dickins CC: Dave Hansen , Mel Gorman , Rik van Riel , Christoph Lameter , Naoya Horiguchi , Steve Capper , "Aneesh Kumar K.V" , Johannes Weiner , Michal Hocko , Jerome Marchand , Sasha Levin , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCHv6 33/36] migrate_pages: try to split pages on qeueuing References: <1433351167-125878-1-git-send-email-kirill.shutemov@linux.intel.com> <1433351167-125878-34-git-send-email-kirill.shutemov@linux.intel.com> In-Reply-To: <1433351167-125878-34-git-send-email-kirill.shutemov@linux.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/03/2015 07:06 PM, Kirill A. Shutemov wrote: > We are not able to migrate THPs. It means it's not enough to split only > PMD on migration -- we need to split compound page under it too. > > Signed-off-by: Kirill A. Shutemov > --- > mm/mempolicy.c | 37 +++++++++++++++++++++++++++++++++---- > 1 file changed, 33 insertions(+), 4 deletions(-) > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index 528f6c467cf1..0b1499c2f890 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -489,14 +489,31 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr, > struct page *page; > struct queue_pages *qp = walk->private; > unsigned long flags = qp->flags; > - int nid; > + int nid, ret; > pte_t *pte; > spinlock_t *ptl; > > - split_huge_pmd(vma, pmd, addr); > - if (pmd_trans_unstable(pmd)) > - return 0; > + if (pmd_trans_huge(*pmd)) { > + ptl = pmd_lock(walk->mm, pmd); > + if (pmd_trans_huge(*pmd)) { > + page = pmd_page(*pmd); > + if (is_huge_zero_page(page)) { > + spin_unlock(ptl); > + split_huge_pmd(vma, pmd, addr); > + } else { > + get_page(page); > + spin_unlock(ptl); > + lock_page(page); > + ret = split_huge_page(page); > + unlock_page(page); > + put_page(page); > + if (ret) > + return 0; > + } > + } > + } > > +retry: > pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); > for (; addr != end; pte++, addr += PAGE_SIZE) { > if (!pte_present(*pte)) > @@ -513,6 +530,18 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr, > nid = page_to_nid(page); > if (node_isset(nid, *qp->nmask) == !!(flags & MPOL_MF_INVERT)) > continue; > + if (PageTail(page) && PageAnon(page)) { Hm, can it really happen that we stumble upon THP tail page here, without first stumbling upon it in the previous hunk above? If so, when? > + get_page(page); > + pte_unmap_unlock(pte - 1, ptl); > + lock_page(page); > + ret = split_huge_page(page); > + unlock_page(page); > + put_page(page); > + /* Failed to split -- skip. */ > + if (ret) > + continue; > + goto retry; > + } > > if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) > migrate_page_add(page, qp->pagelist, flags); >