| Message ID | 20231017163129.2025214-1-zi.yan@sent.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v3,1/2] mm/migrate: correct nr_failed in migrate_pages_sync() | expand |
Zi Yan <zi.yan@sent.com> writes: > From: Zi Yan <ziy@nvidia.com> > > nr_failed was missing the large folio splits from migrate_pages_batch() > and can cause a mismatch between migrate_pages() return value and the > number of not migrated pages, i.e., when the return value of > migrate_pages() is 0, there are still pages left in the from page list. > It will happen when a non-PMD THP large folio fails to migrate due to > -ENOMEM and is split successfully but not all the split pages are not > migrated, migrate_pages_batch() would return non-zero, but > astats.nr_thp_split = 0. nr_failed would be 0 and returned to the caller > of migrate_pages(), but the not migrated pages are left in the from page > list without being added back to LRU lists. > > Fix it by adding a new nr_split counter for large folio splits and adding > it to nr_failed in migrate_page_sync() after migrate_pages_batch() is > done. > > Fixes: 2ef7dbb26990 ("migrate_pages: try migrate in batch asynchronously firstly") > Signed-off-by: Zi Yan <ziy@nvidia.com> > Cc: Baolin Wang <baolin.wang@linux.alibaba.com> > Cc: David Hildenbrand <david@redhat.com> > Cc: Huang Ying <ying.huang@intel.com> > Cc: Matthew Wilcox <willy@infradead.org> LGTM except a trivial issue below, not a big deal. Thanks! Reviewed-by: "Huang, Ying" <ying.huang@intel.com> > --- > mm/migrate.c | 16 +++++++++++++--- > 1 file changed, 13 insertions(+), 3 deletions(-) > > diff --git a/mm/migrate.c b/mm/migrate.c > index c602bf6dec97..fc2e70b17704 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -1495,6 +1495,7 @@ struct migrate_pages_stats { > int nr_thp_succeeded; /* THP migrated successfully */ > int nr_thp_failed; /* THP failed to be migrated */ > int nr_thp_split; /* THP split before migrating */ > + int nr_split; /* Large folio (include THP) split before migrating */ > }; > > /* > @@ -1614,6 +1615,7 @@ static int migrate_pages_batch(struct list_head *from, > int nr_retry_pages = 0; > int pass = 0; > bool is_thp = false; > + bool is_large = false; > struct folio *folio, *folio2, *dst = NULL, *dst2; > int rc, rc_saved = 0, nr_pages; > LIST_HEAD(unmap_folios); > @@ -1629,7 +1631,8 @@ static int migrate_pages_batch(struct list_head *from, > nr_retry_pages = 0; > > list_for_each_entry_safe(folio, folio2, from, lru) { > - is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio); > + is_large = folio_test_large(folio); > + is_thp = is_large && folio_test_pmd_mappable(folio); > nr_pages = folio_nr_pages(folio); > > cond_resched(); > @@ -1649,6 +1652,7 @@ static int migrate_pages_batch(struct list_head *from, > stats->nr_thp_failed++; > if (!try_split_folio(folio, split_folios)) { > stats->nr_thp_split++; > + stats->nr_split++; > continue; > } > stats->nr_failed_pages += nr_pages; > @@ -1677,11 +1681,12 @@ static int migrate_pages_batch(struct list_head *from, > nr_failed++; > stats->nr_thp_failed += is_thp; > /* Large folio NUMA faulting doesn't split to retry. */ > - if (folio_test_large(folio) && !nosplit) { > + if (is_large && !nosplit) { > int ret = try_split_folio(folio, split_folios); > > if (!ret) { > stats->nr_thp_split += is_thp; > + stats->nr_split += is_large; We have tested is_large above, so, "++" is enough here. Not a big deal, only change it if you think it's necessary. > break; > } else if (reason == MR_LONGTERM_PIN && > ret == -EAGAIN) { > @@ -1827,6 +1832,7 @@ static int migrate_pages_sync(struct list_head *from, new_folio_t get_new_folio, > stats->nr_succeeded += astats.nr_succeeded; > stats->nr_thp_succeeded += astats.nr_thp_succeeded; > stats->nr_thp_split += astats.nr_thp_split; > + stats->nr_split += astats.nr_split; > if (rc < 0) { > stats->nr_failed_pages += astats.nr_failed_pages; > stats->nr_thp_failed += astats.nr_thp_failed; > @@ -1834,7 +1840,11 @@ static int migrate_pages_sync(struct list_head *from, new_folio_t get_new_folio, > return rc; > } > stats->nr_thp_failed += astats.nr_thp_split; > - nr_failed += astats.nr_thp_split; > + /* > + * Do not count rc, as pages will be retried below. > + * Count nr_split only, since it includes nr_thp_split. > + */ > + nr_failed += astats.nr_split; > /* > * Fall back to migrate all failed folios one by one synchronously. All > * failed folios except split THPs will be retried, so their failure -- Best Regards, Huang, Ying
On 10/18/2023 12:31 AM, Zi Yan wrote: > From: Zi Yan <ziy@nvidia.com> > > nr_failed was missing the large folio splits from migrate_pages_batch() > and can cause a mismatch between migrate_pages() return value and the > number of not migrated pages, i.e., when the return value of > migrate_pages() is 0, there are still pages left in the from page list. > It will happen when a non-PMD THP large folio fails to migrate due to > -ENOMEM and is split successfully but not all the split pages are not > migrated, migrate_pages_batch() would return non-zero, but > astats.nr_thp_split = 0. nr_failed would be 0 and returned to the caller > of migrate_pages(), but the not migrated pages are left in the from page > list without being added back to LRU lists. > > Fix it by adding a new nr_split counter for large folio splits and adding > it to nr_failed in migrate_page_sync() after migrate_pages_batch() is > done. > > Fixes: 2ef7dbb26990 ("migrate_pages: try migrate in batch asynchronously firstly") > Signed-off-by: Zi Yan <ziy@nvidia.com> > Cc: Baolin Wang <baolin.wang@linux.alibaba.com> > Cc: David Hildenbrand <david@redhat.com> > Cc: Huang Ying <ying.huang@intel.com> > Cc: Matthew Wilcox <willy@infradead.org> > --- LGTM. Feel free to add: Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
diff --git a/mm/migrate.c b/mm/migrate.c index c602bf6dec97..fc2e70b17704 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1495,6 +1495,7 @@ struct migrate_pages_stats { int nr_thp_succeeded; /* THP migrated successfully */ int nr_thp_failed; /* THP failed to be migrated */ int nr_thp_split; /* THP split before migrating */ + int nr_split; /* Large folio (include THP) split before migrating */ }; /* @@ -1614,6 +1615,7 @@ static int migrate_pages_batch(struct list_head *from, int nr_retry_pages = 0; int pass = 0; bool is_thp = false; + bool is_large = false; struct folio *folio, *folio2, *dst = NULL, *dst2; int rc, rc_saved = 0, nr_pages; LIST_HEAD(unmap_folios); @@ -1629,7 +1631,8 @@ static int migrate_pages_batch(struct list_head *from, nr_retry_pages = 0; list_for_each_entry_safe(folio, folio2, from, lru) { - is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio); + is_large = folio_test_large(folio); + is_thp = is_large && folio_test_pmd_mappable(folio); nr_pages = folio_nr_pages(folio); cond_resched(); @@ -1649,6 +1652,7 @@ static int migrate_pages_batch(struct list_head *from, stats->nr_thp_failed++; if (!try_split_folio(folio, split_folios)) { stats->nr_thp_split++; + stats->nr_split++; continue; } stats->nr_failed_pages += nr_pages; @@ -1677,11 +1681,12 @@ static int migrate_pages_batch(struct list_head *from, nr_failed++; stats->nr_thp_failed += is_thp; /* Large folio NUMA faulting doesn't split to retry. */ - if (folio_test_large(folio) && !nosplit) { + if (is_large && !nosplit) { int ret = try_split_folio(folio, split_folios); if (!ret) { stats->nr_thp_split += is_thp; + stats->nr_split += is_large; break; } else if (reason == MR_LONGTERM_PIN && ret == -EAGAIN) { @@ -1827,6 +1832,7 @@ static int migrate_pages_sync(struct list_head *from, new_folio_t get_new_folio, stats->nr_succeeded += astats.nr_succeeded; stats->nr_thp_succeeded += astats.nr_thp_succeeded; stats->nr_thp_split += astats.nr_thp_split; + stats->nr_split += astats.nr_split; if (rc < 0) { stats->nr_failed_pages += astats.nr_failed_pages; stats->nr_thp_failed += astats.nr_thp_failed; @@ -1834,7 +1840,11 @@ static int migrate_pages_sync(struct list_head *from, new_folio_t get_new_folio, return rc; } stats->nr_thp_failed += astats.nr_thp_split; - nr_failed += astats.nr_thp_split; + /* + * Do not count rc, as pages will be retried below. + * Count nr_split only, since it includes nr_thp_split. + */ + nr_failed += astats.nr_split; /* * Fall back to migrate all failed folios one by one synchronously. All * failed folios except split THPs will be retried, so their failure