From: Shengming Hu <hu.shengming@zte.com.cn>

Empty sheaves allocated by alloc_empty_sheaf() should be released with
free_empty_sheaf().

Move the common empty-sheaf initialization into __alloc_empty_sheaf(),
including the capacity and default pfmemalloc state, and use it for
oversized prefilled sheaves as well.

This keeps the prefill paths consistent: after flushing an oversized or
pfmemalloc sheaf, release the now-empty sheaf through free_empty_sheaf()
instead of kfree().

Signed-off-by: Shengming Hu <hu.shengming@zte.com.cn>
---
Changes in v2:
- Rework the change as suggested by Harry.
- Teach __alloc_empty_sheaf() to initialize capacity and pfmemalloc.
- Allocate oversized prefilled sheaves through __alloc_empty_sheaf().
- Free flushed oversized and pfmemalloc sheaves through free_empty_sheaf().
- Link to v1: https://lore.kernel.org/all/20260521195015105Y4zvKHj0TfPZEujixy9Vo@zte.com.cn/

---
 mm/slub.c | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 04692a6f9128..bbe8351f1bfa 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2782,6 +2782,8 @@ static struct slab_sheaf *__alloc_empty_sheaf(struct kmem_cache *s, gfp_t gfp,
 		return NULL;

 	sheaf->cache = s;
+	sheaf->capacity = capacity;
+	sheaf->pfmemalloc = false;

 	stat(s, SHEAF_ALLOC);

@@ -5015,21 +5017,15 @@ kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned int size)

 	if (unlikely(size > s->sheaf_capacity)) {

-		sheaf = kzalloc_flex(*sheaf, objects, size, gfp);
+		sheaf = __alloc_empty_sheaf(s, gfp, size);
 		if (!sheaf)
 			return NULL;

 		stat(s, SHEAF_PREFILL_OVERSIZE);
-		sheaf->cache = s;
-		sheaf->capacity = size;

-		/*
-		 * we do not need to care about pfmemalloc here because oversize
-		 * sheaves area always flushed and freed when returned
-		 */
 		if (!__kmem_cache_alloc_bulk(s, gfp, size,
 					     &sheaf->objects[0])) {
-			kfree(sheaf);
+			free_empty_sheaf(s, sheaf);
 			return NULL;
 		}

@@ -5064,9 +5060,6 @@ kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned int size)
 		sheaf = alloc_empty_sheaf(s, gfp);

 	if (sheaf) {
-		sheaf->capacity = s->sheaf_capacity;
-		sheaf->pfmemalloc = false;
-
 		if (sheaf->size < size &&
 		    __prefill_sheaf_pfmemalloc(s, sheaf, gfp)) {
 			sheaf_flush_unused(s, sheaf);
@@ -5097,7 +5090,7 @@ void kmem_cache_return_sheaf(struct kmem_cache *s, gfp_t gfp,
 	if (unlikely((sheaf->capacity != s->sheaf_capacity)
 		     || sheaf->pfmemalloc)) {
 		sheaf_flush_unused(s, sheaf);
-		kfree(sheaf);
+		free_empty_sheaf(s, sheaf);
 		return;
 	}

-- 
2.25.1