Re: [PATCH] slub: fix __kmem_cache_empty for !CONFIG_SLUB_DEBUG

On Tue, 19 Jun 2018, Shakeel Butt wrote:

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;

Nit: wouldn't cpu be unused if CONFIG_SLUB_DEBUG is disabled?

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;

Wouldn't it just be better to allow {inc,dec}_slabs_node() to adjust the nr_slabs counter instead of doing the per-cpu iteration on every shutdown?