[RFC PATCH v2 2/6] slub: Prepare __slab_free() for unfrozen partial slab out of node partial list

chengming.zhou
2023-10-21T14:44:13Z

From: Chengming Zhou <zhouchengming@bytedance.com>

Now the partial slub will be frozen when taken out of node partial list,
so the __slab_free() will know from "was_frozen" that the partial slab
is not on node partial list and is used by one kmem_cache_cpu.

But we will change this, make partial slabs leave the node partial list
with unfrozen state, so we need to change __slab_free() to use the new
slab_test_node_partial() we just introduced.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
---
mm/slub.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/mm/slub.c b/mm/slub.c
index 3fad4edca34b..adeff8df85ec 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3610,6 +3610,7 @@ static void __slab_free(struct kmem_cache *s, struct slab *slab,
unsigned long counters;
struct kmem_cache_node *n = NULL;
unsigned long flags;
+ bool on_node_partial;

stat(s, FREE_SLOWPATH);

@@ -3657,6 +3658,7 @@ static void __slab_free(struct kmem_cache *s, struct slab *slab,
*/
spin_lock_irqsave(&n->list_lock, flags);

+ on_node_partial = slab_test_node_partial(slab);
}
}

@@ -3685,6 +3687,15 @@ static void __slab_free(struct kmem_cache *s, struct slab *slab,
return;
}

+ /*
+ * This slab was not full and not on the per-node partial list either,
+ * in which case we shouldn't manipulate its list, just early return.
+ */
+ if (prior && !on_node_partial) {
+ spin_unlock_irqrestore(&n->list_lock, flags);
+ return;
+ }
+
if (unlikely(!new.inuse && n->nr_partial >= s->min_partial))
goto slab_empty;

--
2.20.1