From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 5 Sep 2018 08:57:46 +0200 From: Michal Hocko To: Jerome Glisse Cc: Mike Kravetz , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A . Shutemov" , Vlastimil Babka , Naoya Horiguchi , Davidlohr Bueso , Andrew Morton , stable@vger.kernel.org, linux-rdma@vger.kernel.org, Matan Barak , Leon Romanovsky , Dimitri Sivanich Subject: Re: [PATCH v6 1/2] mm: migration: fix migration of huge PMD shared pages Message-ID: <20180905065746.GY14951@dhcp22.suse.cz> References: <20180829183906.GF10223@dhcp22.suse.cz> <20180829211106.GC3784@redhat.com> <20180830105616.GD2656@dhcp22.suse.cz> <20180830140825.GA3529@redhat.com> <20180830161800.GJ2656@dhcp22.suse.cz> <20180830165751.GD3529@redhat.com> <20180830183944.GE3529@redhat.com> <20180903055654.GA14951@dhcp22.suse.cz> <20180904140035.GA3526@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180904140035.GA3526@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: On Tue 04-09-18 10:00:36, Jerome Glisse wrote: > On Mon, Sep 03, 2018 at 07:56:54AM +0200, Michal Hocko wrote: [...] > > And THP migration is still a problem with 4.4 AFAICS. All other cases > > simply split the huge page but THP migration keeps it in one piece and > > as such it is theoretically broken as you have explained. So I would > > stick with what I posted with some more clarifications in the changelog > > if you think it is appropriate (suggestions welcome). > > Reading code there is no THP migration in 4.4 only huge tlb migration. Meh, you are right. For some reason I misread unmap_and_move_huge_page to be also for THP. Sorry for the conusion. My fault! Then it would be indeed safer to use your backport. -- Michal Hocko SUSE Labs