sch_gred: should not use GFP_KERNEL while holding a spinlock

gred_change_vq() is called under sch_tree_lock(sch).

This means a spinlock is held, and we are not allowed to sleep in this
context.

We might pre-allocate memory using GFP_KERNEL before taking spinlock,
but this is not suitable for stable material.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sched/sch_gred.c

@@ -385,7 +385,7 @@ static inline int gred_change_vq(struct Qdisc *sch, int dp,
 	struct gred_sched_data *q;
 
 	if (table->tab[dp] == NULL) {
-		table->tab[dp] = kzalloc(sizeof(*q), GFP_KERNEL);
+		table->tab[dp] = kzalloc(sizeof(*q), GFP_ATOMIC);
 		if (table->tab[dp] == NULL)
 			return -ENOMEM;
 	}