On Thu, 2015-02-26 at 22:32 -0800, Cong Wang wrote:

We can allocate the peer netns id when creating the link
instead of when dumping the link.

This fixes the following kernel warning:

 ===============================
 [ INFO: suspicious RCU usage. ]
 3.19.0+ #805 Tainted: G        W
 -------------------------------
 include/linux/rcupdate.h:538 Illegal context switch in RCU read-side critical section!

 other info that might help us debug this:

This looks very complicated, why even bother ?

I gave an obvious patch fixing root cause, I have no idea why you prefer
over engineering this.

If you believe allocating peer netns id is required at link creation
time, you should explain why.

BTW, (void)peernet2id(dev_net(dev), src_net) can fail, and your fix is
not complete anyway.