syzbot

batman_adv: batadv0: Interface deactivated: batadv_slave_1
batman_adv: batadv0: Removing interface: batadv_slave_1
veth1_macvtap: left promiscuous mode
veth0_macvtap: left promiscuous mode
------------[ cut here ]------------
WARNING: CPU: 1 PID: 13 at net/ipv6/route.c:4857 rt6_multipath_rebalance.part.0+0x879/0xfd0 net/ipv6/route.c:4857
Modules linked in:
CPU: 1 UID: 0 PID: 13 Comm: kworker/u8:1 Not tainted 6.16.0-syzkaller-10499-g89748acdf226 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: netns cleanup_net
RIP: 0010:rt6_multipath_rebalance.part.0+0x879/0xfd0 net/ipv6/route.c:4857
Code: a4 24 58 06 00 00 31 ff 44 89 e6 e8 d1 85 7e f7 45 85 e4 0f 84 44 fe ff ff 41 bf ff ff ff ff e9 82 fe ff ff e8 78 8a 7e f7 90 <0f> 0b 90 48 83 c4 18 5b 5d 41 5c 41 5d 41 5e 41 5f e9 61 8a 7e f7
RSP: 0018:ffffc90000127120 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff8a3cd88a
RDX: ffff88801e2a8000 RSI: ffffffff8a3cdef8 RDI: ffff8880540dbc08
RBP: dffffc0000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffff8880540dbc00
R13: ffffed100a81b792 R14: 0000000000000000 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8881247fb000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd7a2564e9c CR3: 0000000064bbc000 CR4: 00000000003526f0
DR0: 0000000000004f3f DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 rt6_multipath_rebalance net/ipv6/route.c:4849 [inline]
 fib6_ifdown+0x6dc/0x8f0 net/ipv6/route.c:4977
 fib6_clean_node+0x2a7/0x5b0 net/ipv6/ip6_fib.c:2246
 fib6_walk_continue+0x44f/0x8d0 net/ipv6/ip6_fib.c:2171
 fib6_walk+0x182/0x370 net/ipv6/ip6_fib.c:2219
 fib6_clean_tree+0xd4/0x110 net/ipv6/ip6_fib.c:2299
 __fib6_clean_all+0x107/0x2d0 net/ipv6/ip6_fib.c:2315
 rt6_sync_down_dev net/ipv6/route.c:5005 [inline]
 rt6_disable_ip+0x2ec/0x990 net/ipv6/route.c:5010
 addrconf_ifdown.isra.0+0x11d/0x1aa0 net/ipv6/addrconf.c:3853
 addrconf_notify+0x220/0x19e0 net/ipv6/addrconf.c:3776
 notifier_call_chain+0xbc/0x410 kernel/notifier.c:85
 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2229
 call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]
 call_netdevice_notifiers net/core/dev.c:2281 [inline]
 netif_close_many+0x319/0x630 net/core/dev.c:1784
 unregister_netdevice_many_notify+0x563/0x24c0 net/core/dev.c:12126
 unregister_netdevice_many net/core/dev.c:12219 [inline]
 default_device_exit_batch+0x853/0xaf0 net/core/dev.c:12723
 ops_exit_list net/core/net_namespace.c:204 [inline]
 ops_undo_list+0x363/0xab0 net/core/net_namespace.c:251
 cleanup_net+0x408/0x890 net/core/net_namespace.c:682
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c5/0x780 kernel/kthread.c:464
 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>