On Fri, Sep 28, 2018 at 12:02 PM Cong Wang [off-list ref] wrote:

On Fri, Sep 28, 2018 at 11:26 AM Dave Jones [off-list ref] wrote:

quoted

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 3219a2932463..4f9494381635 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c

@@ -330,6 +330,7 @@ void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
        /* It is up to the caller to keep npinfo alive. */
        struct netpoll_info *npinfo;

+       rcu_read_lock();
        lockdep_assert_irqs_disabled();

        npinfo = rcu_dereference_bh(np->dev->npinfo);

I think you probably need rcu_read_lock_bh() to satisfy
rcu_deference_bh()...

But irq is disabled here, so not sure if rcu_read_lock_bh()
could cause trouble... Interesting...