[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, Lorenzo Stoakes, 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