From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754856AbeDCH7b (ORCPT ); Tue, 3 Apr 2018 03:59:31 -0400 Received: from mx2.suse.de ([195.135.220.15]:54931 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752307AbeDCH7a (ORCPT ); Tue, 3 Apr 2018 03:59:30 -0400 Date: Tue, 3 Apr 2018 09:59:28 +0200 From: Michal Hocko To: Naoya Horiguchi Cc: linux-mm@kvack.org, Andrew Morton , Vlastimil Babka , linux-kernel@vger.kernel.org Subject: Re: [PATCH v1] mm: consider non-anonymous thp as unmovable page Message-ID: <20180403075928.GC5501@dhcp22.suse.cz> References: <1522730788-24530-1-git-send-email-n-horiguchi@ah.jp.nec.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1522730788-24530-1-git-send-email-n-horiguchi@ah.jp.nec.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 03-04-18 13:46:28, Naoya Horiguchi wrote: > My testing for the latest kernel supporting thp migration found out 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. Why does it fail? Shmem pages should be movable without any issues. -- Michal Hocko SUSE Labs