[PATCH v1 06/12] mm: thp: make split queue lock safe when LRU pages are reparented
From: Muchun Song <hidden>
Date: 2021-08-14 05:26:14
Also in:
lkml
Subsystem:
memory management, memory management - thp (transparent huge page), the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
Similar to the lruvec lock, we use the same approach to make the split queue lock safe when LRU pages are reparented. Signed-off-by: Muchun Song <redacted> --- mm/huge_memory.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index c49ef28e48c1..22fbf2c74d49 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c@@ -535,9 +535,22 @@ static struct deferred_split *folio_split_queue_lock(struct folio *folio) { struct deferred_split *queue; + rcu_read_lock(); +retry: queue = folio_split_queue(folio); spin_lock(&queue->split_queue_lock); + if (unlikely(split_queue_memcg(queue) != folio_memcg(folio))) { + spin_unlock(&queue->split_queue_lock); + goto retry; + } + + /* + * Preemption is disabled in the internal of spin_lock, which can serve + * as RCU read-side critical sections. + */ + rcu_read_unlock(); + return queue; }
@@ -546,9 +559,19 @@ folio_split_queue_lock_irqsave(struct folio *folio, unsigned long *flags) { struct deferred_split *queue; + rcu_read_lock(); +retry: queue = folio_split_queue(folio); spin_lock_irqsave(&queue->split_queue_lock, *flags); + if (unlikely(split_queue_memcg(queue) != folio_memcg(folio))) { + spin_unlock_irqrestore(&queue->split_queue_lock, *flags); + goto retry; + } + + /* See the comments in folio_split_queue_lock(). */ + rcu_read_unlock(); + return queue; }
--
2.11.0