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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 36C71C282C8 for ; Mon, 28 Jan 2019 18:41:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ECA3D20881 for ; Mon, 28 Jan 2019 18:41:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548700904; bh=4l6tNVEDqnkSnE9k7stv1Qxr+OuimJwqGaWZwRRYV8M=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=tt5hNNC6DYF3j4UyDV0ax5stbQ/Duj1YFa1BqjPq+JANkZmF3h3ZU3ELzGwWzhtLh T09igicXGqEN8VnD47DVd37i+SkJQFIvz7ArPTJ43BX89lmz63RtbtKsv9DVAOJCd3 QwYhqntHljeCCO3AOv7SlbEzu7eeWA4sn9+JJvUI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727399AbfA1Slm (ORCPT ); Mon, 28 Jan 2019 13:41:42 -0500 Received: from mx2.suse.de ([195.135.220.15]:55774 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726744AbfA1Slm (ORCPT ); Mon, 28 Jan 2019 13:41:42 -0500 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 D340EB017; Mon, 28 Jan 2019 18:41:40 +0000 (UTC) Date: Mon, 28 Jan 2019 19:41:39 +0100 From: Michal Hocko To: Andrew Morton Cc: Mikhail Zaslonko , Mikhail Gavrilov , Pavel Tatashin , schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, gerald.schaefer@de.ibm.com, linux-mm@kvack.org, LKML Subject: Re: [PATCH 0/2] mm, memory_hotplug: fix uninitialized pages fallouts. Message-ID: <20190128184139.GR18811@dhcp22.suse.cz> References: <20190128144506.15603-1-mhocko@kernel.org> <20190128095054.4103093dec81f1c904df7929@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190128095054.4103093dec81f1c904df7929@linux-foundation.org> 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 Mon 28-01-19 09:50:54, Andrew Morton wrote: > On Mon, 28 Jan 2019 15:45:04 +0100 Michal Hocko wrote: > > > Mikhail has posted fixes for the two bugs quite some time ago [1]. I > > have pushed back on those fixes because I believed that it is much > > better to plug the problem at the initialization time rather than play > > whack-a-mole all over the hotplug code and find all the places which > > expect the full memory section to be initialized. We have ended up with > > 2830bf6f05fb ("mm, memory_hotplug: initialize struct pages for the full > > memory section") merged and cause a regression [2][3]. The reason is > > that there might be memory layouts when two NUMA nodes share the same > > memory section so the merged fix is simply incorrect. > > > > In order to plug this hole we really have to be zone range aware in > > those handlers. I have split up the original patch into two. One is > > unchanged (patch 2) and I took a different approach for `removable' > > crash. It would be great if Mikhail could test it still works for his > > memory layout. > > > > [1] http://lkml.kernel.org/r/20181105150401.97287-2-zaslonko@linux.ibm.com > > [2] https://bugzilla.redhat.com/show_bug.cgi?id=1666948 > > [3] http://lkml.kernel.org/r/20190125163938.GA20411@dhcp22.suse.cz > > Any thoughts on which kernel version(s) need these patches? My remark in 2830bf6f05fb still holds : This has alwways been problem AFAIU. It just went unnoticed because we : have zeroed memmaps during allocation before f7f99100d8d9 ("mm: stop : zeroing memory during allocation in vmemmap") and so the above test : would simply skip these ranges as belonging to zone 0 or provided a : garbage. : : So I guess we do care for post f7f99100d8d9 kernels mostly and : therefore Fixes: f7f99100d8d9 ("mm: stop zeroing memory during : allocation in vmemmap") But, please let's wait for the patch 1 to be confirmed to fix the issue. -- Michal Hocko SUSE Labs