For !CONFIG_SLUB_DEBUG, SLUB does not maintain the number of slabs
allocated per node for a kmem_cache. Thus, slabs_node() in
__kmem_cache_empty() will always return 0. So, in such situation, it is
required to check per-cpu slabs to make sure if a kmem_cache is empty or
not.
Please note that __kmem_cache_shutdown() and __kmem_cache_shrink() are
not affected by !CONFIG_SLUB_DEBUG as they call flush_all() to clear
per-cpu slabs.
Fixes: f9e13c0a5a33 ("slab, slub: skip unnecessary kasan_cache_shutdown()")
Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Reported-by: Jason A . Donenfeld <Jason@xxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
---
mm/slub.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/mm/slub.c b/mm/slub.c
index a3b8467c14af..731c02b371ae 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3673,9 +3673,23 @@ static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n)
bool __kmem_cache_empty(struct kmem_cache *s)
{
- int node;
+ int cpu, node;
struct kmem_cache_node *n;
+ /*
+ * slabs_node will always be 0 for !CONFIG_SLUB_DEBUG. So, manually
+ * check slabs for all cpus.
+ */
+ if (!IS_ENABLED(CONFIG_SLUB_DEBUG)) {
+ for_each_online_cpu(cpu) {
+ struct kmem_cache_cpu *c;
+
+ c = per_cpu_ptr(s->cpu_slab, cpu);
+ if (c->page || slub_percpu_partial(c))
+ return false;
+ }
+ }
+
for_each_kmem_cache_node(s, node, n)
if (n->nr_partial || slabs_node(s, node))
return false;
--
2.18.0.rc1.244.gcf134e6275-goog
