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=-8.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 D769DC433FF for ; Tue, 13 Aug 2019 13:13:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A793F2067D for ; Tue, 13 Aug 2019 13:13:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="LbiMr+LU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729009AbfHMNNR (ORCPT ); Tue, 13 Aug 2019 09:13:17 -0400 Received: from mail-ed1-f66.google.com ([209.85.208.66]:44064 "EHLO mail-ed1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728134AbfHMNNR (ORCPT ); Tue, 13 Aug 2019 09:13:17 -0400 Received: by mail-ed1-f66.google.com with SMTP id a21so4033924edt.11 for ; Tue, 13 Aug 2019 06:13:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:reply-to:references:mime-version :content-disposition:in-reply-to:user-agent; bh=ubTbMeSv2M83GvfRwkB/P+VL404uyP8HpfpedP/OoAY=; b=LbiMr+LUmaZQrw0UyPVfcE20C2rhk/qkyZVK+3mYVCagAEE8U/paBXrjyllhdz6qtK Wzyo4uPi6N3fin0E1mVY9if56H4zb9YiKT42Fw945pXhXBVv8S0YTiidT67x5mLUlNDf g9b3ExT+UD6gq0KpgfVTPNpdEYLQUgk6xdw1mGSodufjLObjZ8vlHlJcOkuIqQRHQs2h i5tMQILnrg1tWoOOFbCbnBec0cRn2C0XZDoQpYkUbEh1S7kiLV6VU2k6/2ERXkSFxH+s +jkQs/sxXRCPpGZ0782kYlorhUlcaFR7Hnm3JOSxGlLlFVSUG0SKHT6NxMTgWJKS5Sbj 1vSA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:reply-to :references:mime-version:content-disposition:in-reply-to:user-agent; bh=ubTbMeSv2M83GvfRwkB/P+VL404uyP8HpfpedP/OoAY=; b=g8mX1oa0UScWrmcPpPUok3xE/tBKh9u6j1p8fS+5S7NlC/kc4gX6DYOm4LxVRjfCiY JHb6Nt37CjYlnHFnuyRwCk3tSS9gM4Ml+0dcyURH9uZ4bsRBJ1/N3m5Znn4cALj4dzWI MdlgjJZDwsAyJayPl2pIAQ6haULriST2Fl4YRIsZtAmcYSjQ5upFyLkXvAI3lQqo5KrK ckmTW7+7ZiSqX2RA+r27MijFWwlbJ42RvVqTY8Vg3C7xEP70WUYXFXRqv66qOBYZ58HU KXCMHEJF+3e5XX00ZZMfzf3W9QBahKULb0RpII8RL8sABZ0+qLwNmSbTdke5bvxMaH7b FM0g== X-Gm-Message-State: APjAAAW0rs3IGZ0lh62H17oEb9t5nWv/p91N4YZ9CCh4tRh7AowsKGU3 5fen+tC73hdWjon9MCNTpPI= X-Google-Smtp-Source: APXvYqwdvW3aE7k5RgRuOYmrOfG36rPCpQtWz80XoYTilWeyUOHf94znm2sC9lo7U0BNc43D3/8rag== X-Received: by 2002:a50:f285:: with SMTP id f5mr29025998edm.109.1565701995522; Tue, 13 Aug 2019 06:13:15 -0700 (PDT) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id z9sm3562897edd.18.2019.08.13.06.13.14 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 13 Aug 2019 06:13:14 -0700 (PDT) Date: Tue, 13 Aug 2019 13:13:12 +0000 From: Wei Yang To: Michal Hocko Cc: Wei Yang , 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: <20190813131312.l4pzy7ornmc4a5yj@master> Reply-To: Wei Yang References: <20190813020608.10194-1-richardw.yang@linux.intel.com> <20190813075707.GA17933@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190813075707.GA17933@dhcp22.suse.cz> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 13, 2019 at 09:57:07AM +0200, Michal Hocko wrote: >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! > 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 -- Wei Yang Help you, Help me