From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760689AbbLCPrf (ORCPT ); Thu, 3 Dec 2015 10:47:35 -0500 Received: from mail-wm0-f46.google.com ([74.125.82.46]:38865 "EHLO mail-wm0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760672AbbLCPrc (ORCPT ); Thu, 3 Dec 2015 10:47:32 -0500 Date: Thu, 3 Dec 2015 16:47:29 +0100 From: Michal Hocko To: Minchan Kim Cc: Andrew Morton , "Kirill A. Shutemov" , Johannes Weiner , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: memcg uncharge page counter mismatch Message-ID: <20151203154729.GI9264@dhcp22.suse.cz> References: <20151201133455.GB27574@bbox> <20151202101643.GC25284@dhcp22.suse.cz> <20151203013404.GA30779@bbox> <20151203021006.GA31041@bbox> <20151203085451.GC9264@dhcp22.suse.cz> <20151203125950.GA1428@bbox> <20151203133719.GF9264@dhcp22.suse.cz> <20151203134326.GG9264@dhcp22.suse.cz> <20151203145850.GH9264@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151203145850.GH9264@dhcp22.suse.cz> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 03-12-15 15:58:50, Michal Hocko wrote: [....] > Warning, this looks ugly as hell. I was thinking about it some more and it seems that we should rather not bother with partial thp at all and keep it in the original memcg instead. It is way much less code and I do not think this will be too disruptive. Somebody should be holding the thp head, right? Minchan, does this fix the issue you are seeing. --- diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 79a29d564bff..143c933f0b81 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4895,6 +4895,14 @@ static int mem_cgroup_move_charge_pte_range(pmd_t *pmd, switch (get_mctgt_type(vma, addr, ptent, &target)) { case MC_TARGET_PAGE: page = target.page; + /* + * We can have a part of the split pmd here. Moving it + * can be done but it would be too convoluted so simply + * ignore such a partial THP and keep it in original + * memcg. There should be somebody mapping the head. + */ + if (PageCompound(page)) + goto put; if (isolate_lru_page(page)) goto put; if (!mem_cgroup_move_account(page, false, -- Michal Hocko SUSE Labs