| Message ID | de386aa864be9158d2f3b344091419ea7c38b2f7.1666599848.git.baolin.wang@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v3,1/2] mm: migrate: Fix return value if all subpages of THPs are migrated successfully | expand |
On Mon, Oct 24, 2022 at 1:34 AM Baolin Wang <baolin.wang@linux.alibaba.com> 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 <baolin.wang@linux.alibaba.com> > Reviewed-by: Alistair Popple <apopple@nvidia.com> > Cc: <stable@vger.kernel.org> Reviewed-by: Yang Shi <shy828301@gmail.com> > --- > 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 >
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);
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 <baolin.wang@linux.alibaba.com> Reviewed-by: Alistair Popple <apopple@nvidia.com> Cc: <stable@vger.kernel.org> --- 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(+)