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bh=FDnF2RyjYcOK9I2vZApulNeXK7PDktZm4w1Nc3v6ozY=; b=Fup0AgwWeJ12sRV8S3sFF8ZruPSRm/Vshv1PIAQbtKHV+kNrbRz4jwb0Yz2i1fV7VnfKmv bfgE+Yb84fZCg0DSfCDq2ILAqvUbmyFpBlD32VyPX8JJloMTvZnm6Mcod/uFvOrNAhf6FL AJ+RCwxENxTswqdb16pKCVejwkShPHM= X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: CE91A160057 X-Rspam-User: X-Stat-Signature: yza6gtxyo5zwj19xgpysa3ce6ua8xbqr Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=bKLVxGz6; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b="5h4Eu/jH"; spf=pass (imf08.hostedemail.com: domain of osalvador@suse.de designates 195.135.220.29 as permitted sender) smtp.mailfrom=osalvador@suse.de; dmarc=pass (policy=none) header.from=suse.de X-HE-Tag: 1657542382-985538 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 Mon, Jul 11, 2022 at 04:49:46PM +0800, Huang Ying wrote: > If THP or hugetlbfs page migration isn't supported, unmap_and_move() > or unmap_and_move_huge_page() will return -ENOSYS. For THP, splitting > will be tried, but if splitting doesn't succeed, the THP will be left > in "from" list wrongly. If some other pages are retried, the THP > migration failure will counted again. This is fixed via moving the > failure THP from "from" to "ret_pages". > > Another issue of the original code is that the unsupported failure > processing isn't consistent between THP and hugetlbfs page. Make them > consistent in this patch to make the code easier to be understood too. > > Signed-off-by: "Huang, Ying" > Fixes: 5984fabb6e82 ("mm: move_pages: report the number of non-attempted pages") > Reviewed-by: Baolin Wang > Cc: Zi Yan > Cc: Yang Shi > --- > mm/migrate.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/mm/migrate.c b/mm/migrate.c > index 4bceba143db0..8cce73b7c046 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -1192,10 +1192,8 @@ static int unmap_and_move_huge_page(new_page_t get_new_page, > * tables or check whether the hugepage is pmd-based or not before > * kicking migration. > */ > - if (!hugepage_migration_supported(page_hstate(hpage))) { > - list_move_tail(&hpage->lru, ret); > + if (!hugepage_migration_supported(page_hstate(hpage))) > return -ENOSYS; > - } > > if (page_count(hpage) == 1) { > /* page was freed from under us. So we are done. */ > @@ -1392,6 +1390,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, > * page will be put back > * -EAGAIN: stay on the from list > * -ENOMEM: stay on the from list > + * -ENOSYS: stay on the from list > * Other errno: put on ret_pages list then splice to > * from list > */ > @@ -1421,6 +1420,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, > } > > nr_failed_pages += nr_subpages; > + list_move_tail(&page->lru, &ret_pages); I must be missing something, but migrate_pages() calls unmap_and_move_huge_page() with ret being ret_pages, so list_move_tail(&hpage->lru, ret) == list_move_tail(&page->lru, &ret_pages) Yet, you say "This is fixed via moving the failure THP from "from" to "ret_pages"". /me confused. -- Oscar Salvador SUSE Labs