Re: Latest net-next from GIT panic

[Eric Dumazet]

On Wed, 2017-09-20 at 16:03 +0200, Paweł Staszewski wrote:
> Nit much more after adding this patch
> 
> https://bugzilla.kernel.org/attachment.cgi?id=258529
> 

This is why I suggested to replace the BUG() in another mail

So :

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 
f535779d9dc1dfe36934c2abba4e43d053ac5d6f..220cd12456754876edf2d3ef13195e82d70d5c74
 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3331,7 +3331,15 @@ void netdev_run_todo(void);
  */
 static inline void dev_put(struct net_device *dev)
 {
-       this_cpu_dec(*dev->pcpu_refcnt);
+       int __percpu *pref = READ_ONCE(dev->pcpu_refcnt);
+
+       if (!pref) {
+               pr_err("no pcpu_refcnt on dev %p(%s) state %d dismantle %d\n",
+                      dev, dev->name, dev->reg_state, dev->dismantle);
+               for (;;)
+                       cpu_relax();
+       }
+       this_cpu_dec(*pref);
 }
 
 /**