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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 30D0CC4360C for ; Sat, 12 Oct 2019 10:32:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 06807206A1 for ; Sat, 12 Oct 2019 10:32:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728933AbfJLKcw (ORCPT ); Sat, 12 Oct 2019 06:32:52 -0400 Received: from mx2.suse.de ([195.135.220.15]:53830 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727262AbfJLKaw (ORCPT ); Sat, 12 Oct 2019 06:30:52 -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 E3AE6B5BE; Sat, 12 Oct 2019 10:30:49 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Date: Sat, 12 Oct 2019 12:30:48 +0200 From: osalvador To: Qian Cai Cc: Naoya Horiguchi , linux-kernel@vger.kernel.org, linux-mm@kvack.org, David Hildenbrand , Michal Hocko , Mike Kravetz , owner-linux-mm@kvack.org Subject: Re: memory offline infinite loop after soft offline In-Reply-To: <1570829564.5937.36.camel@lca.pw> References: <1570829564.5937.36.camel@lca.pw> Message-ID: <55ff76d109062a87fb209ecddf167b71@suse.de> X-Sender: osalvador@suse.de User-Agent: Roundcube Webmail Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019-10-11 23:32, Qian Cai wrote: > # /opt/ltp/runtest/bin/move_pages12 > move_pages12.c:263: INFO: Free RAM 258988928 kB > move_pages12.c:281: INFO: Increasing 2048kB hugepages pool on node 0 to > 4 > move_pages12.c:291: INFO: Increasing 2048kB hugepages pool on node 8 to > 4 > move_pages12.c:207: INFO: Allocating and freeing 4 hugepages on node 0 > move_pages12.c:207: INFO: Allocating and freeing 4 hugepages on node 8 > move_pages12.c:197: PASS: Bug not reproduced > move_pages12.c:197: PASS: Bug not reproduced > > for mem in $(ls -d /sys/devices/system/memory/memory*); do >         echo offline > $mem/state >         echo online > $mem/state > done > > That LTP move_pages12 test will first madvise(MADV_SOFT_OFFLINE) for a > range. > Then, one of "echo offline" will trigger an infinite loop in > __offline_pages() > here, I did not deeply check whether this issue is really related soft-offline. As is, soft-offline has a few issues that can lead to tricky problems. Actually, lately I have received quite a few reports from customers where testing soft-offline resulted in applications crashing all around. I am working on a re-implementation to fix those issues [1]. I yet have to fix a bug I found yesterday though, but it should be quite trivial to fix it up, so I should be able to send a new re-spin next week. [1] https://lore.kernel.org/patchwork/cover/1126173/ Thanks > > /* check again */ > ret = walk_system_ram_range(start_pfn, end_pfn - start_pfn, >     NULL, check_pages_isolated_cb); > } while (ret); > > because check_pages_isolated_cb() always return -EBUSY from > test_pages_isolated(), > > > pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn, > skip_hwpoisoned_pages); > ... > return pfn < end_pfn ? -EBUSY : 0; > > The root cause is in __test_page_isolated_in_pageblock() where "pfn" is > always > less than "end_pfn" because the associated page is not a PageBuddy. > > while (pfn < end_pfn) { > ... > else > break; > > return pfn; > > Adding a dump_page() for that pfn shows, > > [  101.665160][ T8885] pfn = 77501, end_pfn = 78000 > [  101.665245][ T8885] page:c00c000001dd4040 refcount:0 mapcount:0 > mapping:0000000000000000 index:0x0 > [  101.665329][ T8885] flags: 0x3fffc000000000() > [  101.665391][ T8885] raw: 003fffc000000000 0000000000000000 > ffffffff01dd0500 > 0000000000000000 > [  101.665498][ T8885] raw: 0000000000000000 0000000000000000 > 00000000ffffffff > 0000000000000000 > [  101.665588][ T8885] page dumped because: soft_offline > [  101.665639][ T8885] page_owner tracks the page as freed > [  101.665697][ T8885] page last allocated via order 5, migratetype > Movable, > gfp_mask > 0x346cca(GFP_HIGHUSER_MOVABLE|__GFP_NOWARN|__GFP_RETRY_MAYFAIL|__GFP_COMP|__GFP_ > THISNODE) > [  101.665924][ T8885]  prep_new_page+0x3c0/0x440 > [  101.665962][ T8885]  get_page_from_freelist+0x2568/0x2bb0 > [  101.666059][ T8885]  __alloc_pages_nodemask+0x1b4/0x670 > [  101.666115][ T8885]  alloc_fresh_huge_page+0x244/0x6e0 > [  101.666183][ T8885]  alloc_migrate_huge_page+0x30/0x70 > [  101.666254][ T8885]  alloc_new_node_page+0xc4/0x380 > [  101.666325][ T8885]  migrate_pages+0x3b4/0x19e0 > [  101.666375][ T8885]  do_move_pages_to_node.isra.29.part.30+0x44/0xa0 > [  101.666464][ T8885]  kernel_move_pages+0x498/0xfc0 > [  101.666520][ T8885]  sys_move_pages+0x28/0x40 > [  101.666643][ T8885]  system_call+0x5c/0x68 > [  101.666665][ T8885] page last free stack trace: > [  101.666704][ T8885]  __free_pages_ok+0xa4c/0xd40 > [  101.666773][ T8885]  update_and_free_page+0x2dc/0x5b0 > [  101.666821][ T8885]  free_huge_page+0x2dc/0x740 > [  101.666875][ T8885]  __put_compound_page+0x64/0xc0 > [  101.666926][ T8885]  putback_active_hugepage+0x228/0x390 > [  101.666990][ T8885]  migrate_pages+0xa78/0x19e0 > [  101.667048][ T8885]  soft_offline_page+0x314/0x1050 > [  101.667117][ T8885]  sys_madvise+0x1068/0x1080 > [  101.667185][ T8885]  system_call+0x5c/0x68