From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH v2] ipv6: addrconf: Fix recursive spin lock call
Date: Sat, 06 Feb 2016 03:09:44 -0500 (EST)
Message-ID: <20160206.030944.1340132870709460187.davem@davemloft.net>
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Cc: netdev@vger.kernel.org, edumazet@google.com, ek@google.com,
	hannes@stressinduktion.org
To: subashab@codeaurora.org
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From: subashab@codeaurora.org
Date: Tue, 2 Feb 2016 02:11:10 -0000

> A rcu stall with the following backtrace was seen on a system with
> forwarding, optimistic_dad and use_optimistic set. To reproduce,
> set these flags and allow ipv6 autoconf.
> 
> This occurs because the device write_lock is acquired while already
> holding the read_lock. Back trace below -
 ...
> v2: do addrconf_dad_kick inside read lock and then acquire write
> lock for ipv6_ifa_notify as suggested by Eric
> 
> Fixes: 7fd2561e4ebdd ("net: ipv6: Add a sysctl to make optimistic
> addresses useful candidates")
> 
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Erik Kline <ek@google.com>
> Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
> Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>

Applied and queued up for -stable, thanks.