Re: [PATCH 1/2 net-next v5] ipv6: addrconf: fix temp address generation after prefix deprecation

[Ido Schimmel <idosch@nvidia.com>]

On Sat, May 23, 2026 at 12:38:10PM +0200, Fernando Fernandez Mancera wrote:
> When a router temporarily deprecates an IPv6 prefix (either by sending a
> Router Advertisement with Preferred Lifetime = 0 or by letting the
> lifetime expire) and later restores it, the kernel permanently loses its
> ability to generate temporary privacy addresses (RFC 8981) for that
> prefix.
> 
> This happens because the address worker attempts to generate a
> replacement temporary address when the current one nears expiration. As
> the base prefix is deprecated already, the generation fails after
> marking the temporary address as already having spawned a replacement
> (ifp->regen_count++).
> 
> When the router eventually restores the prefix, the temporary address
> becomes active again. However, once it naturally expires, the address
> worker sees this temporary address already tried to generate one and
> skips the regeneration.
> 
> Fix the issue by resetting the regen_count check of the latest temp
> address generated for the prefix updated by the incoming RA.
> 
> Reported-by: Łukasz Stelmach <steelman@post.pl>
> Closes: https://lore.kernel.org/netdev/87340td30q.fsf%25steelman@post.pl/
> Suggested-by: Ido Schimmel <idosch@nvidia.com>
> Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>

Reviewed-by: Ido Schimmel <idosch@nvidia.com>