memory management - kfree_skb() after skb_dequeue() freezes linux kernel -

i'm implementing flow control in custom protocol in linux kernel. when receive ack, want remove acked packets write queue. here's code

for(i = (ack->sequence - qp->first_unack); i>0&&sk->sk_write_queue.qlen>0; i++){     skb_del = skb_dequeue(&sk->sk_write_queue);     qp->first_unack++;     kfree_skb(skb_del); } 

i kernel freeze code. works however, when comment out kfree(skb_del). ideas why happening? how else can free memory?

as skbs queued socket can use provided socket apis;

sk_eat_skb(struct sock *sk, struct sk_buff *skb, bool copied_early)  // copied_ealy = 0 

for more details can track tcp_recvmsg, there impementation flow

moreove why using custom apis queuing/dequeuing loop on own. go through include/net/sock.h hope necessary details