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 B8B6DC282C7 for ; Tue, 29 Jan 2019 20:24:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 875B620880 for ; Tue, 29 Jan 2019 20:24:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548793486; bh=+ciIrXZeW1+Y/CSQkTTPO9u050N6ssuVfUcyMfLjOZg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=k5twztJ55b11FCdBVNaNz/rqnF+9yZf425t5VUnvVcABRgVPq3YyaWb5rxe2Twk6I UTeq1Keb7rkwLJ6jA8OxRgcay3q2g459u7hIOm8kmx2mkR8hgVekopASvsamqPXXdN ho9xv0zD+7VPvHnbpOSOsykOPIrAaMaZBYjoCDGs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729225AbfA2UYo (ORCPT ); Tue, 29 Jan 2019 15:24:44 -0500 Received: from mx2.suse.de ([195.135.220.15]:42280 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727473AbfA2UYo (ORCPT ); Tue, 29 Jan 2019 15:24:44 -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 60854AA71; Tue, 29 Jan 2019 20:24:42 +0000 (UTC) Date: Tue, 29 Jan 2019 21:24:40 +0100 From: Michal Hocko To: Mikhail Gavrilov Cc: Gerald Schaefer , Mikhail Zaslonko , Andrew Morton , Pavel Tatashin , schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, linux-mm@kvack.org, LKML Subject: Re: [PATCH 0/2] mm, memory_hotplug: fix uninitialized pages fallouts. Message-ID: <20190129202440.GP18811@dhcp22.suse.cz> References: <20190128144506.15603-1-mhocko@kernel.org> <20190129141447.34aa9d0c@thinkpad> <20190129134920.GM18811@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 29-01-19 22:38:19, Mikhail Gavrilov wrote: > On Tue, 29 Jan 2019 at 18:49, Michal Hocko wrote: > > > > On Tue 29-01-19 14:14:47, Gerald Schaefer wrote: > > > On Mon, 28 Jan 2019 15:45:04 +0100 > > > Michal Hocko wrote: > > > > > > > Hi, > > > > 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 > > > > > > I verified that both patches fix the issues we had with valid_zones > > > (with mem=2050M) and removable (with mem=3075M). > > > > > > However, the call trace in the description of your patch 1 is wrong. > > > You basically have the same call trace for test_pages_in_a_zone in > > > both patches. The "removable" patch should have the call trace for > > > is_mem_section_removable from Mikhails original patches: > > > > Thanks for testing. Can I use you Tested-by? > > > > > CONFIG_DEBUG_VM_PGFLAGS=y > > > kernel parameter mem=3075M > > > -------------------------- > > > page:000003d08300c000 is uninitialized and poisoned > > > page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) > > > Call Trace: > > > ([<000000000038596c>] is_mem_section_removable+0xb4/0x190) > > > [<00000000008f12fa>] show_mem_removable+0x9a/0xd8 > > > [<00000000008cf9c4>] dev_attr_show+0x34/0x70 > > > [<0000000000463ad0>] sysfs_kf_seq_show+0xc8/0x148 > > > [<00000000003e4194>] seq_read+0x204/0x480 > > > [<00000000003b53ea>] __vfs_read+0x32/0x178 > > > [<00000000003b55b2>] vfs_read+0x82/0x138 > > > [<00000000003b5be2>] ksys_read+0x5a/0xb0 > > > [<0000000000b86ba0>] system_call+0xdc/0x2d8 > > > Last Breaking-Event-Address: > > > [<000000000038596c>] is_mem_section_removable+0xb4/0x190 > > > Kernel panic - not syncing: Fatal exception: panic_on_oops > > > > Yeah, this is c&p mistake on my end. I will use this trace instead. > > Thanks for spotting. > > > Michal, I am late? I do not think so. I plan to repost tomorrow with the updated changelog and gathered review and tested-by tags. Can I assume yours as well? > I am also tested these patches and can confirm that issue fixed again > with new approach. > I also attach two dmesg first when issue was reproduced and second > with applied patch (problem not reproduced). Thanks! -- Michal Hocko SUSE Labs