net: sched: use kvmalloc() for class hash tables

High order GFP_KERNEL allocations can stress the host badly.

Use modern kvmalloc_array()/kvfree() instead of custom
allocations.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/sch_api.c

@@ -621,14 +621,10 @@ EXPORT_SYMBOL(qdisc_watchdog_cancel);
 
 static struct hlist_head *qdisc_class_hash_alloc(unsigned int n)
 {
-	unsigned int size = n * sizeof(struct hlist_head), i;
 	struct hlist_head *h;
+	unsigned int i;
 
-	if (size <= PAGE_SIZE)
-		h = kmalloc(size, GFP_KERNEL);
-	else
-		h = (struct hlist_head *)
-			__get_free_pages(GFP_KERNEL, get_order(size));
+	h = kvmalloc_array(n, sizeof(struct hlist_head), GFP_KERNEL);
 
 	if (h != NULL) {
 		for (i = 0; i < n; i++)
@@ -637,16 +633,6 @@ static struct hlist_head *qdisc_class_hash_alloc(unsigned int n)
 	return h;
 }
 
-static void qdisc_class_hash_free(struct hlist_head *h, unsigned int n)
-{
-	unsigned int size = n * sizeof(struct hlist_head);
-
-	if (size <= PAGE_SIZE)
-		kfree(h);
-	else
-		free_pages((unsigned long)h, get_order(size));
-}
-
 void qdisc_class_hash_grow(struct Qdisc *sch, struct Qdisc_class_hash *clhash)
 {
 	struct Qdisc_class_common *cl;
@@ -679,7 +665,7 @@ void qdisc_class_hash_grow(struct Qdisc *sch, struct Qdisc_class_hash *clhash)
 	clhash->hashmask = nmask;
 	sch_tree_unlock(sch);
 
-	qdisc_class_hash_free(ohash, osize);
+	kvfree(ohash);
 }
 EXPORT_SYMBOL(qdisc_class_hash_grow);
 
@@ -699,7 +685,7 @@ EXPORT_SYMBOL(qdisc_class_hash_init);
 
 void qdisc_class_hash_destroy(struct Qdisc_class_hash *clhash)
 {
-	qdisc_class_hash_free(clhash->hash, clhash->hashsize);
+	kvfree(clhash->hash);
 }
 EXPORT_SYMBOL(qdisc_class_hash_destroy);