Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754453AbbLDQBj (ORCPT ); Fri, 4 Dec 2015 11:01:39 -0500 Received: from gum.cmpxchg.org ([85.214.110.215]:47702 "EHLO gum.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753494AbbLDQBi (ORCPT ); Fri, 4 Dec 2015 11:01:38 -0500 Date: Fri, 4 Dec 2015 11:01:28 -0500 From: Johannes Weiner To: Michal Hocko Cc: Minchan Kim , Andrew Morton , "Kirill A. Shutemov" , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: memcg uncharge page counter mismatch Message-ID: <20151204160128.GA24431@cmpxchg.org> 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> <20151203154729.GI9264@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151203154729.GI9264@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 Content-Length: 1359 Lines: 34 On Thu, Dec 03, 2015 at 04:47:29PM +0100, Michal Hocko wrote: > 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, Acked-by: Johannes Weiner The charge moving concept is fundamentally flawed and its implementation here is incomplete and races with reclaim. Really, nobody should be using this. Absent any actual regression reports, a minimal fix to stop this code from generating warnings should be enough. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/