Re: [PATCH 1/1] mm/thp: clear deferred split shrinker bits when queues drain

[Wei Yang]

On Tue, Jun 02, 2026 at 12:34:53PM +0800, Lance Yang wrote:
>From: Lance Yang <lance.yang@xxxxxxxxx>
>
>deferred_split_count() returns the raw list_lru count. When the per-memcg,
>per-node list is empty, that count is 0.
>
>That skips scanning, but it does not tell memcg reclaim that the shrinker
>is empty. shrink_slab_memcg() only clears the memcg shrinker bit when the
>count callback reports SHRINK_EMPTY.
>
>Return SHRINK_EMPTY for an empty deferred split list, so the bit can be
>cleared once the queue has drained.
>
>Signed-off-by: Lance Yang <lance.yang@xxxxxxxxx>
>---
> mm/huge_memory.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
>diff --git a/mm/huge_memory.c b/mm/huge_memory.c
>index 72f6caf0fec6..62d598290c3b 100644
>--- a/mm/huge_memory.c
>+++ b/mm/huge_memory.c
>@@ -4397,7 +4397,10 @@ void deferred_split_folio(struct folio *folio, bool partially_mapped)
> static unsigned long deferred_split_count(struct shrinker *shrink,
> 		struct shrink_control *sc)
> {
>-	return list_lru_shrink_count(&deferred_split_lru, sc);
>+	unsigned long count;
>+
>+	count = list_lru_shrink_count(&deferred_split_lru, sc);
>+	return count ?: SHRINK_EMPTY;
> }

Looks you are right, thanks.

Reviewed-by: Wei Yang <richard.weiyang@xxxxxxxxx>

> 
> static bool thp_underused(struct folio *folio)
>-- 
>2.49.0
>

-- 
Wei Yang
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