From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f200.google.com (mail-wr0-f200.google.com [209.85.128.200]) by kanga.kvack.org (Postfix) with ESMTP id 9E5AF6B0007 for ; Tue, 3 Apr 2018 03:59:30 -0400 (EDT) Received: by mail-wr0-f200.google.com with SMTP id b9so3461262wrj.15 for ; Tue, 03 Apr 2018 00:59:30 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id t15si1726557wrb.190.2018.04.03.00.59.29 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 03 Apr 2018 00:59:29 -0700 (PDT) Date: Tue, 3 Apr 2018 09:59:28 +0200 From: Michal Hocko 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> Sender: owner-linux-mm@kvack.org List-ID: To: Naoya Horiguchi Cc: linux-mm@kvack.org, Andrew Morton , Vlastimil Babka , 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