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=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 D5DADC4646A for ; Wed, 12 Sep 2018 12:21:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8BD2520839 for ; Wed, 12 Sep 2018 12:21:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8BD2520839 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727689AbeILRZv (ORCPT ); Wed, 12 Sep 2018 13:25:51 -0400 Received: from mx2.suse.de ([195.135.220.15]:49466 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726491AbeILRZu (ORCPT ); Wed, 12 Sep 2018 13:25:50 -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 DECBCAD53; Wed, 12 Sep 2018 12:21:32 +0000 (UTC) Date: Wed, 12 Sep 2018 14:21:32 +0200 From: Michal Hocko To: Zaslonko Mikhail Cc: Mikhail Zaslonko , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Pavel.Tatashin@microsoft.com, osalvador@suse.de, gerald.schaefer@de.ibm.com Subject: Re: [PATCH] memory_hotplug: fix the panic when memory end is not on the section boundary Message-ID: <20180912122132.GF10951@dhcp22.suse.cz> References: <20180910123527.71209-1-zaslonko@linux.ibm.com> <20180910131754.GG10951@dhcp22.suse.cz> <04b427ad-df4e-67bd-2942-2a7a2cccf1aa@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <04b427ad-df4e-67bd-2942-2a7a2cccf1aa@linux.vnet.ibm.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 11-09-18 16:06:23, Zaslonko Mikhail wrote: [...] > > Well, I am afraid this is not the proper solution. We are relying on the > > full pageblock worth of initialized struct pages at many other place. We > > used to do that in the past because we have initialized the full > > section but this has been changed recently. Pavel, do you have any ideas > > how to deal with this partial mem sections now? > > I think this is not related to the recent changes of memory initialization. > If > you mean deferred init case, the problem exists even without > CONFIG_DEFERRED_STRUCT_PAGE_INIT kernel option. This is more about struct page initialization (which doesn't clear whole) memmap area and as such it stays unitialized. So you are right this is a much older issue we just happened to not notice without explicit memmap poisoning. -- Michal Hocko SUSE Labs