From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933075AbbFVLf6 (ORCPT ); Mon, 22 Jun 2015 07:35:58 -0400 Received: from mta-out1.inet.fi ([62.71.2.229]:34261 "EHLO johanna2.rokki.sonera.fi" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753942AbbFVLfv (ORCPT ); Mon, 22 Jun 2015 07:35:51 -0400 RazorGate-KAS: Rate: 5 RazorGate-KAS: {RECEIVED: dynamic ip detected} RazorGate-KAS: Envelope from: RazorGate-KAS: Version: 5.5.3 RazorGate-KAS: LuaCore: 80 2014-11-10_18-01-23 260f8afb9361da3c7edfd3a8e3a4ca908191ad29 RazorGate-KAS: Method: none RazorGate-KAS: Lua profiles 69136 [Nov 12 2014] RazorGate-KAS: Status: not_detected Date: Mon, 22 Jun 2015 14:35:25 +0300 From: "Kirill A. Shutemov" To: Vlastimil Babka Cc: "Kirill A. Shutemov" , Andrew Morton , Andrea Arcangeli , Hugh Dickins , 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 Message-ID: <20150622113525.GE7934@node.dhcp.inet.fi> References: <1433351167-125878-1-git-send-email-kirill.shutemov@linux.intel.com> <1433351167-125878-34-git-send-email-kirill.shutemov@linux.intel.com> <55795477.90808@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <55795477.90808@suse.cz> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 11, 2015 at 11:27:19AM +0200, Vlastimil Babka wrote: > 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? The first hunk catch PMD-mapped THP and here we deal with PTE-mapped. The scenario: fault in a THP, split PMD (not page) e.g. with mprotect() and then try to migrate. -- Kirill A. Shutemov -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in Please read the FAQ at http://www.tux.org/lkml/