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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 X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: D55C940006 X-Stat-Signature: ikmc8zsg48177uij6758by6bdescyzjx X-HE-Tag: 1690366505-379297 X-HE-Meta: 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 McN8UA/3 OrWN8F1JYv5hcn1rv4rskXcrcr7A0UwOW8gjCgARc8NTDIpQMPEHwdAdJR3xU8IgiSf0hwtPcXfAtasaPO1mKOE8SpIGGZLXAs/Y9tWsmFN2aIv9zsIZknn0P+iX6k5xxzaI5NcRzfrRJCy+r+r8Olz9y/WpvzYMVZ2vGcug+WEqv8Ogr5iVrGFkkYk2dZKqD7/4wNCgnBYncg9TKr7pxW5GssaUN2glIWf5MH7XdYTpIOspV/7XMBkF4cr0n6SRicrWgxkfK7aPRVFdvXfz71LH0JGBNnBfZOeRBOhpkt76Sbw9klPNRfHFmqGW0cU02Xrafu9t+zAK/Gjmw3hobSvf0+Vcdk51RDOpY X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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