From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752260AbeDIHPp convert rfc822-to-8bit (ORCPT ); Mon, 9 Apr 2018 03:15:45 -0400 Received: from tyo162.gate.nec.co.jp ([114.179.232.162]:45655 "EHLO tyo162.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752181AbeDIHPn (ORCPT ); Mon, 9 Apr 2018 03:15:43 -0400 From: Naoya Horiguchi To: Michal Hocko CC: "Kirill A. Shutemov" , Zi Yan , "linux-mm@kvack.org" , Andrew Morton , Vlastimil Babka , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] mm: shmem: enable thp migration (Re: [PATCH v1] mm: consider non-anonymous thp as unmovable page) Thread-Topic: [PATCH] mm: shmem: enable thp migration (Re: [PATCH v1] mm: consider non-anonymous thp as unmovable page) Thread-Index: AQHTzVRbJLbJcuvidESXEazGlmX3mKPymtkAgAAfroCABLjegA== Date: Mon, 9 Apr 2018 07:14:57 +0000 Message-ID: <20180409071456.GA8693@hori1.linux.bs1.fc.nec.co.jp> References: <20180405085927.GC6312@dhcp22.suse.cz> <20180405122838.6a6b35psizem4tcy@node.shutemov.name> <20180405124830.GJ6312@dhcp22.suse.cz> <20180405134045.7axuun6d7ufobzj4@node.shutemov.name> <20180405150547.GN6312@dhcp22.suse.cz> <20180405155551.wchleyaf4rxooj6m@node.shutemov.name> <20180405160317.GP6312@dhcp22.suse.cz> <20180406030706.GA2434@hori1.linux.bs1.fc.nec.co.jp> <20180406051452.GB23467@hori1.linux.bs1.fc.nec.co.jp> <20180406070815.GC8286@dhcp22.suse.cz> In-Reply-To: <20180406070815.GC8286@dhcp22.suse.cz> Accept-Language: en-US, ja-JP Content-Language: ja-JP X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.128.101.18] Content-Type: text/plain; charset="iso-2022-jp" Content-ID: <46617E8EBD5C594E93BC92C5255CD427@gisp.nec.co.jp> Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-TM-AS-MML: disable Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 06, 2018 at 09:08:15AM +0200, Michal Hocko wrote: > On Fri 06-04-18 05:14:53, Naoya Horiguchi wrote: > > On Fri, Apr 06, 2018 at 03:07:11AM +0000, Horiguchi Naoya(堀口 直也) wrote: > > ... > > > ----- > > > From e31ec037701d1cc76b26226e4b66d8c783d40889 Mon Sep 17 00:00:00 2001 > > > From: Naoya Horiguchi > > > Date: Fri, 6 Apr 2018 10:58:35 +0900 > > > Subject: [PATCH] mm: enable thp migration for shmem thp > > > > > > My testing for the latest kernel supporting thp migration showed an > > > infinite loop in offlining the memory block that is filled with shmem > > > thps. We can get out of the loop with a signal, but kernel should > > > return with failure in this case. > > > > > > What happens in the loop is that scan_movable_pages() repeats returning > > > the same pfn without any progress. That's because page migration always > > > fails for shmem thps. > > > > > > In memory offline code, memory blocks containing unmovable pages should > > > be prevented from being offline targets by has_unmovable_pages() inside > > > start_isolate_page_range(). So it's possible to change migratability > > > for non-anonymous thps to avoid the issue, but it introduces more complex > > > and thp-specific handling in migration code, so it might not good. > > > > > > So this patch is suggesting to fix the issue by enabling thp migration > > > for shmem thp. Both of anon/shmem thp are migratable so we don't need > > > precheck about the type of thps. > > > > > > Fixes: commit 72b39cfc4d75 ("mm, memory_hotplug: do not fail offlining too early") > > > Signed-off-by: Naoya Horiguchi > > > Cc: stable@vger.kernel.org # v4.15+ > > > > ... oh, I don't think this is suitable for stable. > > Michal's fix in another email can come first with "CC: stable", > > then this one. > > Anyway I want to get some feedback on the change of this patch. > > My patch is indeed much simpler but it depends on [1] and that doesn't > sound like a stable material as well because it depends on onether 2 > patches. Maybe we need some other hack for 4.15 if we really care enough. > > [1] http://lkml.kernel.org/r/20180103082555.14592-4-mhocko@kernel.org OK, so I like just giving up sending to stable.