bpf: Convert hash map to bpf_mem_alloc.

Convert bpf hash map to use bpf memory allocator.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220902211058.60789-3-alexei.starovoitov@gmail.com

kernel/bpf/hashtab.c

@@ -14,6 +14,7 @@
 #include "percpu_freelist.h"
 #include "bpf_lru_list.h"
 #include "map_in_map.h"
+#include <linux/bpf_mem_alloc.h>
 
 #define HTAB_CREATE_FLAG_MASK						\
 	(BPF_F_NO_PREALLOC | BPF_F_NO_COMMON_LRU | BPF_F_NUMA_NODE |	\
@@ -92,6 +93,7 @@ struct bucket {
 
 struct bpf_htab {
 	struct bpf_map map;
+	struct bpf_mem_alloc ma;
 	struct bucket *buckets;
 	void *elems;
 	union {
@@ -576,6 +578,10 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
 			if (err)
 				goto free_prealloc;
 		}
+	} else {
+		err = bpf_mem_alloc_init(&htab->ma, htab->elem_size);
+		if (err)
+			goto free_map_locked;
 	}
 
 	return &htab->map;
@@ -586,6 +592,7 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
 	for (i = 0; i < HASHTAB_MAP_LOCK_COUNT; i++)
 		free_percpu(htab->map_locked[i]);
 	bpf_map_area_free(htab->buckets);
+	bpf_mem_alloc_destroy(&htab->ma);
 free_htab:
 	lockdep_unregister_key(&htab->lockdep_key);
 	bpf_map_area_free(htab);
@@ -862,7 +869,7 @@ static void htab_elem_free(struct bpf_htab *htab, struct htab_elem *l)
 	if (htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH)
 		free_percpu(htab_elem_get_ptr(l, htab->map.key_size));
 	check_and_free_fields(htab, l);
-	kfree(l);
+	bpf_mem_cache_free(&htab->ma, l);
 }
 
 static void htab_elem_free_rcu(struct rcu_head *head)
@@ -986,9 +993,7 @@ static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
 				l_new = ERR_PTR(-E2BIG);
 				goto dec_count;
 			}
-		l_new = bpf_map_kmalloc_node(&htab->map, htab->elem_size,
-					     GFP_NOWAIT | __GFP_NOWARN,
-					     htab->map.numa_node);
+		l_new = bpf_mem_cache_alloc(&htab->ma);
 		if (!l_new) {
 			l_new = ERR_PTR(-ENOMEM);
 			goto dec_count;
@@ -1007,7 +1012,7 @@ static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
 			pptr = bpf_map_alloc_percpu(&htab->map, size, 8,
 						    GFP_NOWAIT | __GFP_NOWARN);
 			if (!pptr) {
-				kfree(l_new);
+				bpf_mem_cache_free(&htab->ma, l_new);
 				l_new = ERR_PTR(-ENOMEM);
 				goto dec_count;
 			}
@@ -1429,6 +1434,10 @@ static void delete_all_elements(struct bpf_htab *htab)
 {
 	int i;
 
+	/* It's called from a worker thread, so disable migration here,
+	 * since bpf_mem_cache_free() relies on that.
+	 */
+	migrate_disable();
 	for (i = 0; i < htab->n_buckets; i++) {
 		struct hlist_nulls_head *head = select_bucket(htab, i);
 		struct hlist_nulls_node *n;
@@ -1439,6 +1448,7 @@ static void delete_all_elements(struct bpf_htab *htab)
 			htab_elem_free(htab, l);
 		}
 	}
+	migrate_enable();
 }
 
 static void htab_free_malloced_timers(struct bpf_htab *htab)
@@ -1502,6 +1512,7 @@ static void htab_map_free(struct bpf_map *map)
 	bpf_map_free_kptr_off_tab(map);
 	free_percpu(htab->extra_elems);
 	bpf_map_area_free(htab->buckets);
+	bpf_mem_alloc_destroy(&htab->ma);
 	for (i = 0; i < HASHTAB_MAP_LOCK_COUNT; i++)
 		free_percpu(htab->map_locked[i]);
 	lockdep_unregister_key(&htab->lockdep_key);