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dkim=pass header.d=gmail.com header.s=20210112 header.b=krW7g60I; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf20.hostedemail.com: domain of shy828301@gmail.com designates 209.85.210.173 as permitted sender) smtp.mailfrom=shy828301@gmail.com X-Stat-Signature: a6pbymw73g4ohquicwb53h937k7em53x X-HE-Tag: 1666632083-253163 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, Oct 24, 2022 at 1:34 AM Baolin Wang wrote: > > During THP migration, if THPs are not migrated but they are split and all > subpages are migrated successfully, migrate_pages() will still return the > number of THP pages that were not migrated. This will confuse the callers > of migrate_pages(). For example, the longterm pinning will failed though > all pages are migrated successfully. > > Thus we should return 0 to indicate that all pages are migrated in this > case > > Fixes: b5bade978e9b ("mm: migrate: fix the return value of migrate_pages()") > Signed-off-by: Baolin Wang > Reviewed-by: Alistair Popple > Cc: Reviewed-by: Yang Shi > --- > Changes from v2: > - Add Fixes tag suggested by Yang Shi and Huang, Ying. > - Drop 'nr_thp_split' validation suggested by Alistair. > - Add reviewed tag from Alistair. > - Update the commit message suggested by Andrew. > Changes from v1: > - Fix the return value of migrate_pages() instead of fixing the > callers' validation. > --- > mm/migrate.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/mm/migrate.c b/mm/migrate.c > index 8e5eb6e..2eb16f8 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -1582,6 +1582,13 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, > */ > list_splice(&ret_pages, from); > > + /* > + * Return 0 in case all subpages of fail-to-migrate THPs are > + * migrated successfully. > + */ > + if (list_empty(from)) > + rc = 0; > + > count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded); > count_vm_events(PGMIGRATE_FAIL, nr_failed_pages); > count_vm_events(THP_MIGRATION_SUCCESS, nr_thp_succeeded); > -- > 1.8.3.1 >