Re: [PATCH net-next] ipv6: move IFA_F_PERMANENT percpu allocation in process scope

[David Ahern <dsahern@kernel.org>]

On 3/24/26 9:22 AM, Paolo Abeni wrote:
> Observed at boot time:
> 
>  CPU: 43 UID: 0 PID: 3595 Comm: (t-daemon) Not tainted 6.12.0 #1

6.12 ???

> IFA_F_PERMANENT addresses require the allocation of a bunch of percpu
> pointers, currently in atomic scope.
> 
> Similar to commit 51454ea42c1a ("ipv6: fix locking issues with loops
> over idev->addr_list"), move fixup_permanent_addr() outside the
> &idev->lock scope, and do the allocations with GFP_KERNEL. With such
> change fixup_permanent_addr() is invoked with the BH enabled, and the
> ifp lock acquired there needs the BH variant.
> 
> Note that we don't need to acquire a reference to the permanent
> addresses before releasing the mentioned write lock, because
> addrconf_permanent_addr() runs under RTNL and ifa removal always happens
> under RTNL, too.
> 
> Also the PERMANENT flag is constant in the relevant scope, as it can be
> cleared only by inet6_addr_modify() under the RTNL lock.
> 
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> ---
> explicitly targeting net-next as this is IMHO an improvement more than a
> bug fix
> ---
>  net/ipv6/addrconf.c | 32 ++++++++++++++++++++------------
>  1 file changed, 20 insertions(+), 12 deletions(-)
> 

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