netdev - Re: [PATCH net-next v2 16/21] net/ipv6: Add gfp

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Message-ID: <70692d90-1a96-01e3-776c-51b3a27138b0@gmail.com>
Date:   Wed, 18 Apr 2018 10:30:54 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     David Ahern <dsahern@...il.com>,
        Eric Dumazet <eric.dumazet@...il.com>, netdev@...r.kernel.org
Cc:     davem@...emloft.net, idosch@...sch.org, roopa@...ulusnetworks.com,
        weiwan@...gle.com, kafai@...com, yoshfuji@...ux-ipv6.org
Subject: Re: [PATCH net-next v2 16/21] net/ipv6: Add gfp_flags to route add
 functions



On 04/18/2018 10:10 AM, David Ahern wrote:
> On 4/18/18 11:06 AM, Eric Dumazet wrote:
>>
>>
>> On 04/17/2018 05:33 PM, David Ahern wrote:
>>> Most FIB entries can be added using memory allocated with GFP_KERNEL.
>>> Add gfp_flags to ip6_route_add and addrconf_dst_alloc. Code paths that
>>> can be reached from the packet path (e.g., ndisc and autoconfig) or
>>> atomic notifiers use GFP_ATOMIC; paths from user context (adding
>>> addresses and routes) use GFP_KERNEL.
>>>
>>> Signed-off-by: David Ahern <dsahern@...il.com>
>>> ---
>>
>>
>> Hmmm....
>>
>> ipv6_ifa_notify() calls __ipv6_ifa_notify() under rcu_read_lock_bh()/rcu_read_unlock_bh()
>>
>> So using GFP_KERNEL in __ipv6_ifa_notify() is certainly not allowed.
>>
>>
> 
> Thanks for catching that. Will add fix to my followup set.
> 
BTW, I am not sure why we use rcu_read_lock_bh()/rcu_read_unlock_bh() there :/

Maybe it is no longer needed.