From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755669AbcAMIRr (ORCPT ); Wed, 13 Jan 2016 03:17:47 -0500 Received: from TYO202.gate.nec.co.jp ([210.143.35.52]:35269 "EHLO tyo202.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752035AbcAMIRp convert rfc822-to-8bit (ORCPT ); Wed, 13 Jan 2016 03:17:45 -0500 From: Naoya Horiguchi To: Liang Chen CC: "riel@redhat.com" , "mgorman@suse.de" , "akpm@linux-foundation.org" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Gavin Guo Subject: Re: [PATCH V2] mm: mempolicy: skip non-migratable VMAs when setting MPOL_MF_LAZY Thread-Topic: [PATCH V2] mm: mempolicy: skip non-migratable VMAs when setting MPOL_MF_LAZY Thread-Index: AQHRSP7hon3/u0QBWE+L3HxqdrxNkp74jHWA Date: Wed, 13 Jan 2016 08:16:12 +0000 Message-ID: <20160113081611.GA29313@hori1.linux.bs1.fc.nec.co.jp> References: <1452138758-30031-1-git-send-email-liangchen.linux@gmail.com> In-Reply-To: <1452138758-30031-1-git-send-email-liangchen.linux@gmail.com> Accept-Language: ja-JP, en-US Content-Language: ja-JP X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.128.101.30] Content-Type: text/plain; charset="iso-2022-jp" Content-ID: <483ADF7CCFA3D747870627E79CC6B656@gisp.nec.co.jp> Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Liang, On Thu, Jan 07, 2016 at 11:52:38AM +0800, Liang Chen wrote: > MPOL_MF_LAZY is not visible from userspace since 'commit a720094ded8c > ("mm: mempolicy: Hide MPOL_NOOP and MPOL_MF_LAZY from userspace for now")' > , but it should still skip non-migratable VMAs such as VM_IO, VM_PFNMAP, > and VM_HUGETLB VMAs, and avoid useless overhead of minor faults. > > Signed-off-by: Liang Chen > Signed-off-by: Gavin Guo > --- > Changes since v2: > - Add more description into the changelog > > We have been evaluating the enablement of MPOL_MF_LAZY again, and found > this issue. And we decided to push this patch upstream no matter if we > finally determine to propose re-enablement of MPOL_MF_LAZY or not. Since > it can be a potential problem even if MPOL_MF_LAZY is not enabled this > time. > --- > mm/mempolicy.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index 87a1779..436ff411 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -610,7 +610,8 @@ static int queue_pages_test_walk(unsigned long start, unsigned long end, > > if (flags & MPOL_MF_LAZY) { > /* Similar to task_numa_work, skip inaccessible VMAs */ > - if (vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)) > + if (vma_migratable(vma) && > + vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)) > change_prot_numa(vma, start, endvma); > return 1; > } task_numa_work() does more vma checks before entering change_prot_numa() like vma_policy_mof(), is_vm_hugetlb_page(), and (vma->vm_flags & VM_MIXEDMAP). So is it better to use the same check set to limit the target vmas to auto-numa enabled ones? Thanks, Naoya Horiguchi