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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DC472C001DE for ; Wed, 26 Jul 2023 10:15:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233089AbjGZKPJ (ORCPT ); Wed, 26 Jul 2023 06:15:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48686 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230013AbjGZKPG (ORCPT ); Wed, 26 Jul 2023 06:15:06 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 135F91995 for ; Wed, 26 Jul 2023 03:15:05 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id BC72C1692; Wed, 26 Jul 2023 03:15:47 -0700 (PDT) Received: from [10.57.77.6] (unknown [10.57.77.6]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D6C833F67D; Wed, 26 Jul 2023 03:15:02 -0700 (PDT) Message-ID: <01797bb1-43c1-62a1-e483-61fa67061b9c@arm.com> Date: Wed, 26 Jul 2023 11:15:00 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH -V3 1/8] migrate: fix syscall move_pages() return value for failure To: Huang Ying , Andrew Morton , Alistair Popple Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Oscar Salvador , Baolin Wang , Zi Yan , Yang Shi References: <20220817081408.513338-1-ying.huang@intel.com> <20220817081408.513338-2-ying.huang@intel.com> From: Ryan Roberts In-Reply-To: <20220817081408.513338-2-ying.huang@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17/08/2022 09:14, Huang Ying wrote: > The return value of move_pages() syscall is incorrect when counting > the remaining pages to be migrated. Hi Huang, Alistair, I've noticed that this patch from Huang has caused the mm/migration selftest (authored by Alistair) to start failing (see bisection log below). Of the 3 tests, migration.private_anon and migration.private_anon_thp continue to pass, but migration.shared_anon fails: # RUN migration.shared_anon ... Didn't migrate 1 pages # migration.c:167:shared_anon:Expected migrate(ptr, self->n1, self->n2) (-2) == 0 (0) # shared_anon: Test terminated by assertion # FAIL migration.shared_anon not ok 2 migration.shared_anon The failure occurs due to the return code of move_pages() and this patch has changed the return code handling in the kernel, so it makes sense: int migrate(uint64_t *ptr, int n1, int n2) { int ret, tmp; int status = 0; struct timespec ts1, ts2; if (clock_gettime(CLOCK_MONOTONIC, &ts1)) return -1; while (1) { if (clock_gettime(CLOCK_MONOTONIC, &ts2)) return -1; if (ts2.tv_sec - ts1.tv_sec >= RUNTIME) return 0; ret = move_pages(0, 1, (void **) &ptr, &n2, &status, MPOL_MF_MOVE_ALL); if (ret) { if (ret > 0) printf("Didn't migrate %d pages\n", ret); <<<< HERE else perror("Couldn't migrate pages"); return -2; } tmp = n2; n2 = n1; n1 = tmp; } return 0; } I haven't looked any further and am not sure what the correct fix is. I wondered if either you might be able to offer a solution? Thanks, Ryan git bisect start # bad: [6eaae198076080886b9e7d57f4ae06fa782f90ef] Linux 6.5-rc3 git bisect bad 6eaae198076080886b9e7d57f4ae06fa782f90ef # good: [2c85ebc57b3e1817b6ce1a6b703928e113a90442] Linux 5.10 git bisect good 2c85ebc57b3e1817b6ce1a6b703928e113a90442 # good: [d710d370c4911e83da5d2bc43d4a2c3b56bd27e7] Merge tag 's390-5.18-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux git bisect good d710d370c4911e83da5d2bc43d4a2c3b56bd27e7 # bad: [8715c6d3100fc7c6edddf29af4a399a1c12d028c] Merge tag 'for-6.2/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm git bisect bad 8715c6d3100fc7c6edddf29af4a399a1c12d028c # good: [12b68040a5e468068fd7f4af1150eab8f6e96235] Merge tag 'media/v5.20-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media git bisect good 12b68040a5e468068fd7f4af1150eab8f6e96235 # good: [7e6739b9336e61fe23ca4e2c8d1fda8f19f979bf] Merge tag 'drm-next-2022-10-05' of git://anongit.freedesktop.org/drm/drm git bisect good 7e6739b9336e61fe23ca4e2c8d1fda8f19f979bf # bad: [524d0c68826bc1adf9d1946e540eb4f7b16699a7] Merge tag 'ceph-for-6.1-rc1' of https://github.com/ceph/ceph-client git bisect bad 524d0c68826bc1adf9d1946e540eb4f7b16699a7 # good: [29926f1cd3535f565f200430d5b6a794543fe130] fbdev: mb862xx: Fix check of return value from irq_of_parse_and_map() git bisect good 29926f1cd3535f565f200430d5b6a794543fe130 # good: [d4013bc4d49f6da8178a340348369bb9920225c9] Merge tag 'bitmap-6.1-rc1' of https://github.com/norov/linux git bisect good d4013bc4d49f6da8178a340348369bb9920225c9 # bad: [ac1e8c6c95bf805c699656046aef0a05205edfbd] Merge tag '6.1-rc-smb3-client-fixes-part1' of git://git.samba.org/sfrench/cifs-2.6 git bisect bad ac1e8c6c95bf805c699656046aef0a05205edfbd # bad: [f80be4571b19b9fd8dd1528cd2a2f123aff51f70] kmsan: add KMSAN runtime core git bisect bad f80be4571b19b9fd8dd1528cd2a2f123aff51f70 # bad: [c4c84f06285e48f80e9843d0775ad92714ffc35a] fs/proc/task_mmu: stop using linked list and highest_vm_end git bisect bad c4c84f06285e48f80e9843d0775ad92714ffc35a # good: [8c004d1fc1497d9a6d92ea968bd58230af59a492] jbd2: replace ll_rw_block() git bisect good 8c004d1fc1497d9a6d92ea968bd58230af59a492 # bad: [f76c83378851f8e70f032848c4e61203f39480e4] mm: multi-gen LRU: optimize multiple memcgs git bisect bad f76c83378851f8e70f032848c4e61203f39480e4 # good: [36537a67d3561bfe2b3654161d6c9008fff84d43] mm, hwpoison: avoid unneeded page_mapped_in_vma() overhead in collect_procs_anon() git bisect good 36537a67d3561bfe2b3654161d6c9008fff84d43 # bad: [5fc30916b5cda697a7eb8f1167c38c27100a793a] migrate_pages(): fix failure counting for THP subpages retrying git bisect bad 5fc30916b5cda697a7eb8f1167c38c27100a793a # good: [2e3468778dbe3ec389a10c21a703bb8e5be5cfbc] mm: remember young/dirty bit for page migrations git bisect good 2e3468778dbe3ec389a10c21a703bb8e5be5cfbc # good: [f347c9d2697fcbbb64e077f7113a3887a181b8c0] filemap: make the accounting of thrashing more consistent git bisect good f347c9d2697fcbbb64e077f7113a3887a181b8c0 # bad: [9c62ff005fc774fb2ba14223b0d865a8aca48fb5] migrate_pages(): remove unnecessary list_safe_reset_next() git bisect bad 9c62ff005fc774fb2ba14223b0d865a8aca48fb5 # bad: [a7504ed14f9b5e873599b2487eb95062dd0b65f8] migrate: fix syscall move_pages() return value for failure git bisect bad a7504ed14f9b5e873599b2487eb95062dd0b65f8 # first bad commit: [a7504ed14f9b5e873599b2487eb95062dd0b65f8] migrate: fix syscall move_pages() return value for failure