netdev - Re: [PATCH net] ipv6: addrconf: break critical section in addrconf_verify

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Message-Id: <20180129.142431.368786370257576620.davem@davemloft.net>
Date:   Mon, 29 Jan 2018 14:24:31 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     eric.dumazet@...il.com
Cc:     idosch@...sch.org, hkallweit1@...il.com, netdev@...r.kernel.org
Subject: Re: [PATCH net] ipv6: addrconf: break critical section in
 addrconf_verify_rtnl()

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Fri, 26 Jan 2018 16:10:43 -0800

> From: Eric Dumazet <edumazet@...gle.com>
> 
> Heiner reported a lockdep splat [1]
> 
> This is caused by attempting GFP_KERNEL allocation while RCU lock is
> held and BH blocked.
> 
> We believe that addrconf_verify_rtnl() could run for a long period,
> so instead of using GFP_ATOMIC here as Ido suggested, we should break
> the critical section and restart it after the allocation.
> 
> 
> [1]
 ...
> Fixes: f3d9832e56c4 ("ipv6: addrconf: cleanup locking in ipv6_add_addr")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Reported-by: Heiner Kallweit <hkallweit1@...il.com>

Applied and queued up for v4.15 -stable, thanks.