netdev - Re: [PATCH net V4] Exempt multicast addresses from five-second neighbor lifetime

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Date:   Thu, 12 Nov 2020 21:06:42 -0700
From:   David Ahern <dsahern@...il.com>
To:     Jeff Dike <jdike@...mai.com>, netdev@...r.kernel.org
Cc:     Jakub Kicinski <kuba@...nel.org>
Subject: Re: [PATCH net V4] Exempt multicast addresses from five-second
 neighbor lifetime

On 11/12/20 6:58 PM, Jeff Dike wrote:
> Commit 58956317c8de ("neighbor: Improve garbage collection")
> guarantees neighbour table entries a five-second lifetime.  Processes
> which make heavy use of multicast can fill the neighour table with
> multicast addresses in five seconds.  At that point, neighbour entries
> can't be GC-ed because they aren't five seconds old yet, the kernel
> log starts to fill up with "neighbor table overflow!" messages, and
> sends start to fail.
> 
> This patch allows multicast addresses to be thrown out before they've
> lived out their five seconds.  This makes room for non-multicast
> addresses and makes messages to all addresses more reliable in these
> circumstances.
> 
> Fixes: 58956317c8de ("neighbor: Improve garbage collection")
> Signed-off-by: Jeff Dike <jdike@...mai.com>
> ---
>  include/net/neighbour.h | 1 +
>  net/core/neighbour.c    | 2 ++
>  net/ipv4/arp.c          | 6 ++++++
>  net/ipv6/ndisc.c        | 7 +++++++
>  4 files changed, 16 insertions(+)
> 


Reviewed-by: David Ahern <dsahern@...nel.org>