On Thu, 30 Jan 2014, Andrew Morton wrote: > > What's funnier is that tmp_name isn't required at all since > > kmem_cache_create_memcg() is just going to do a kstrdup() on it anyway, so > > you could easily just pass in the pointer to memory that has been > > allocated for s->name rather than allocating memory twice. > > We need a buffer to sprintf() into. > Yeah, it shouldn't be temporary it should be the one and only allocation. We should construct the name in memcg_create_kmem_cache() and be done with it. > diff -puN mm/memcontrol.c~mm-memcontrolc-memcg_create_kmem_cache-tweaks mm/memcontrol.c > --- a/mm/memcontrol.c~mm-memcontrolc-memcg_create_kmem_cache-tweaks > +++ a/mm/memcontrol.c > @@ -3400,24 +3400,18 @@ void mem_cgroup_destroy_cache(struct kme > static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg, > struct kmem_cache *s) > { > - struct kmem_cache *new = NULL; > - static char *tmp_name = NULL; > - static DEFINE_MUTEX(mutex); /* protects tmp_name */ > + struct kmem_cache *new; > + char *tmp_name; > > BUG_ON(!memcg_can_account_kmem(memcg)); > > - mutex_lock(&mutex); > /* > - * kmem_cache_create_memcg duplicates the given name and > - * cgroup_name for this name requires RCU context. > - * This static temporary buffer is used to prevent from > - * pointless shortliving allocation. > + * kmem_cache_create_memcg duplicates the given name and cgroup_name() > + * for this name requires rcu_read_lock(). > */ > - if (!tmp_name) { > - tmp_name = kmalloc(PATH_MAX, GFP_KERNEL); > - if (!tmp_name) > - goto out; > - } > + tmp_name = kmalloc(PATH_MAX, GFP_KERNEL); > + if (!tmp_name) > + return NULL; > > rcu_read_lock(); > snprintf(tmp_name, PATH_MAX, "%s(%d:%s)", s->name, > @@ -3430,8 +3424,7 @@ static struct kmem_cache *memcg_create_k > new->allocflags |= __GFP_KMEMCG; > else > new = s; > -out: > - mutex_unlock(&mutex); > + kfree(tmp_name); > return new; > } > This is fine, but kmem_cache_create_memcg() is still just going to do a pointless kstrdup() on it which isn't necessary. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>