From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: kernel BUG in ipmr_queue_xmit()
Date: Thu, 29 Oct 2015 21:15:42 -0700
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Cc: Florian Westphal <fw@strlen.de>, netdev@vger.kernel.org,
	ani@anirban.org, fruggeri@arista.com
To: Ani Sinha <ani@arista.com>
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On Thu, 2015-10-29 at 18:41 -0700, Ani Sinha wrote:

> 
> Signed-off-by: Ani Sinha <ani@arista.com>
> ---
>  net/ipv4/ipmr.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
> index 866ee89..48df3cc 100644
> --- a/net/ipv4/ipmr.c
> +++ b/net/ipv4/ipmr.c
> @@ -936,7 +936,9 @@ static void ipmr_cache_resolve(struct net *net, struct mr_table *mrt,
>  
>  			rtnl_unicast(skb, net, NETLINK_CB(skb).portid);
>  		} else {
> +			preempt_disable();
>  			ip_mr_forward(net, mrt, skb, c, 0);
> +			preempt_enable();
>  		}
>  	}
>  }

I do not believe this fix is correct.

Better replace the 
IP_INC_STATS_BH() by IP_INC_STATS()

and IP_ADD_STATS_BH() by IP_ADD_STATS()