[ Upstream commit eb02688c5c ]
The CI is hitting some aperiodic hangup at device removal time in the
pmtu.sh self-test:
unregister_netdevice: waiting for veth_A-R1 to become free. Usage count = 6
ref_tracker: veth_A-R1@ffff888013df15d8 has 1/5 users at
dst_init+0x84/0x4a0
dst_alloc+0x97/0x150
ip6_dst_alloc+0x23/0x90
ip6_rt_pcpu_alloc+0x1e6/0x520
ip6_pol_route+0x56f/0x840
fib6_rule_lookup+0x334/0x630
ip6_route_output_flags+0x259/0x480
ip6_dst_lookup_tail.constprop.0+0x5c2/0x940
ip6_dst_lookup_flow+0x88/0x190
udp_tunnel6_dst_lookup+0x2a7/0x4c0
vxlan_xmit_one+0xbde/0x4a50 [vxlan]
vxlan_xmit+0x9ad/0xf20 [vxlan]
dev_hard_start_xmit+0x10e/0x360
__dev_queue_xmit+0xf95/0x18c0
arp_solicit+0x4a2/0xe00
neigh_probe+0xaa/0xf0
While the first suspect is the dst_cache, explicitly tracking the dst
owing the last device reference via probes proved such dst is held by
the nexthop in the originating fib6_info.
Similar to commit f5b51fe804 ("ipv6: route: purge exception on
removal"), we need to explicitly release the originating fib info when
disconnecting a to-be-removed device from a live ipv6 dst: move the
fib6_info cleanup into ip6_dst_ifdown().
Tested running:
./pmtu.sh cleanup_ipv6_exception
in a tight loop for more than 400 iterations with no spat, running an
unpatched kernel I observed a splat every ~10 iterations.
Fixes: f88d8ea67f ("ipv6: Plumb support for nexthop object in a fib6_info")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/604c45c188c609b732286b47ac2a451a40f6cf6d.1730828007.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit eb02688c5c)
[Harshit: Resolved conflict due to missing commit: e5f80fcf86 ("ipv6:
give an IPv6 dev to blackhole_netdev") and commit: b4cb4a1391 ("net:
use unrcu_pointer() helper") in linux-5.15.y]
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
77aa9855a8