diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst index 514f75e71b02..3389bdd8940e 100644 --- a/Documentation/admin-guide/mm/transhuge.rst +++ b/Documentation/admin-guide/mm/transhuge.rst @@ -515,6 +515,13 @@ nr_anon might be currently entirely mapped or have partially unmapped/unused subpages. +nr_anon_partially_mapped + the number of anonymous THP which are likely partially mapped, possibly + wasting memory, and have been queued for deferred memory reclamation. + Note that in corner some cases (e.g., failed migration), we might detect + an anonymous THP as "partially mapped" and count it here, even though it + is not actually partially mapped anymore. + As the system ages, allocating huge pages may be expensive as the system uses memory compaction to copy data around memory to free a huge page for use. There are some counters in ``/proc/vmstat`` to help diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 37c715579d19..b9d642d626e4 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -268,6 +268,7 @@ enum mthp_stat_item { MTHP_STAT_SPLIT_FAILED, MTHP_STAT_SPLIT_DEFERRED, MTHP_STAT_NR_ANON, + MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, __MTHP_STAT_COUNT }; diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 60a40049866a..2d1dd704652d 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -559,6 +559,7 @@ DEFINE_MTHP_STAT_ATTR(split, MTHP_STAT_SPLIT); DEFINE_MTHP_STAT_ATTR(split_failed, MTHP_STAT_SPLIT_FAILED); DEFINE_MTHP_STAT_ATTR(split_deferred, MTHP_STAT_SPLIT_DEFERRED); DEFINE_MTHP_STAT_ATTR(nr_anon, MTHP_STAT_NR_ANON); +DEFINE_MTHP_STAT_ATTR(nr_anon_partially_mapped, MTHP_STAT_NR_ANON_PARTIALLY_MAPPED); static struct attribute *stats_attrs[] = { &anon_fault_alloc_attr.attr, @@ -570,6 +571,7 @@ static struct attribute *stats_attrs[] = { &split_failed_attr.attr, &split_deferred_attr.attr, &nr_anon_attr.attr, + &nr_anon_partially_mapped_attr.attr, NULL, }; @@ -3499,6 +3501,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) if (folio_order(folio) > 1 && !list_empty(&folio->_deferred_list)) { ds_queue->split_queue_len--; + mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); list_del_init(&folio->_deferred_list); } spin_unlock(&ds_queue->split_queue_lock); @@ -3563,6 +3566,7 @@ void __folio_undo_large_rmappable(struct folio *folio) spin_lock_irqsave(&ds_queue->split_queue_lock, flags); if (!list_empty(&folio->_deferred_list)) { ds_queue->split_queue_len--; + mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); list_del_init(&folio->_deferred_list); } spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); @@ -3603,6 +3607,7 @@ void deferred_split_folio(struct folio *folio) if (list_empty(&folio->_deferred_list)) { count_vm_event(THP_DEFERRED_SPLIT_PAGE); count_mthp_stat(folio_order(folio), MTHP_STAT_SPLIT_DEFERRED); + mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, 1); list_add_tail(&folio->_deferred_list, &ds_queue->split_queue); ds_queue->split_queue_len++; #ifdef CONFIG_MEMCG @@ -3654,6 +3659,7 @@ static unsigned long deferred_split_scan(struct shrinker *shrink, list_move(&folio->_deferred_list, &list); } else { /* We lost race with folio_put() */ + mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); list_del_init(&folio->_deferred_list); ds_queue->split_queue_len--; }