sch_gred: should not use GFP_KERNEL while holding a spinlock

sch_gred: should not use GFP_KERNEL while holding a spinlock

[ Upstream commit 3f1e6d3fd37bd4f25e5b19f1c7ca21850426c33f ]

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: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>