From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 13CA7C32750 for ; Tue, 13 Aug 2019 07:57:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CCCBD20665 for ; Tue, 13 Aug 2019 07:57:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565683030; bh=CU7+0tpIXR//vhJ0kdSzFDCu6DcGx9rZ0rdX0SDIKiA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=YUp35FEsjaj7sBL3DfFd1vVrf4cVnpOQno1xTCZwyZ9Axhb+aQ0gJqsgYl/JUFIbM qS0ej9IVKrI2QTKJMz67aYrgBTXJseZIk2Cn3GxldIL+hZBJDtWKFguAh3P9sagO2D 128JO8nmYxUkzqwEwFrekvSOVKAJf7j4NttjKxS8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727874AbfHMH5J (ORCPT ); Tue, 13 Aug 2019 03:57:09 -0400 Received: from mx2.suse.de ([195.135.220.15]:36278 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726551AbfHMH5J (ORCPT ); Tue, 13 Aug 2019 03:57:09 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 34D64AD3A; Tue, 13 Aug 2019 07:57:08 +0000 (UTC) Date: Tue, 13 Aug 2019 09:57:07 +0200 From: Michal Hocko To: Wei Yang Cc: akpm@linux-foundation.org, osalvador@suse.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/hotplug: prevent memory leak when reuse pgdat Message-ID: <20190813075707.GA17933@dhcp22.suse.cz> References: <20190813020608.10194-1-richardw.yang@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190813020608.10194-1-richardw.yang@linux.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 13-08-19 10:06:08, Wei Yang wrote: > When offline a node in try_offline_node, pgdat is not released. So that > pgdat could be reused in hotadd_new_pgdat. While we re-allocate > pgdat->per_cpu_nodestats if this pgdat is reused. > > This patch prevents the memory leak by just allocate per_cpu_nodestats > when it is a new pgdat. Yes this makes sense! I was slightly confused why we haven't initialized the allocated pcp area because __alloc_percpu does GFP_KERNEL without __GFP_ZERO but then I've just found out that the zeroying is done regardless. A bit unexpected... > NOTE: This is not tested since I didn't manage to create a case to > offline a whole node. If my analysis is not correct, please let me know. > > Signed-off-by: Wei Yang Acked-by: Michal Hocko Thanks! > --- > mm/memory_hotplug.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index c73f09913165..efaf9e6f580a 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -933,8 +933,11 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start) > if (!pgdat) > return NULL; > > + pgdat->per_cpu_nodestats = > + alloc_percpu(struct per_cpu_nodestat); > arch_refresh_nodedata(nid, pgdat); > } else { > + int cpu; > /* > * Reset the nr_zones, order and classzone_idx before reuse. > * Note that kswapd will init kswapd_classzone_idx properly > @@ -943,6 +946,12 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start) > pgdat->nr_zones = 0; > pgdat->kswapd_order = 0; > pgdat->kswapd_classzone_idx = 0; > + for_each_online_cpu(cpu) { > + struct per_cpu_nodestat *p; > + > + p = per_cpu_ptr(pgdat->per_cpu_nodestats, cpu); > + memset(p, 0, sizeof(*p)); > + } > } > > /* we can use NODE_DATA(nid) from here */ > @@ -952,7 +961,6 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start) > > /* init node's zones as empty zones, we don't have any present pages.*/ > free_area_init_core_hotplug(nid); > - pgdat->per_cpu_nodestats = alloc_percpu(struct per_cpu_nodestat); > > /* > * The node we allocated has no zone fallback lists. For avoiding > -- > 2.17.1 > -- Michal Hocko SUSE Labs