WARNING in rt6_multipath_rebalance

Status: auto-obsoleted due to no activity on 2026/05/19 11:13
Reported-by: syzbot+797eb03bd68dbed8d216@syzkaller.appspotmail.com
First crash: 191d, last: 191d
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in rt6_multipath_rebalance (2) net -1 292 353d 474d 0/29 auto-obsoleted due to no activity on 2025/11/07 22:31
linux-6.6 WARNING in rt6_multipath_rebalance -1 4 374d 389d 0/2 auto-obsoleted due to no activity on 2025/11/17 21:21
linux-6.1 WARNING in rt6_multipath_rebalance -1 3 352d 410d 0/3 auto-obsoleted due to no activity on 2025/12/09 15:49
upstream WARNING in rt6_multipath_rebalance net -1 2 527d 531d 0/29 closed as invalid on 2025/04/08 14:38

Sample crash report:
device veth1_macvtap left promiscuous mode
device veth0_macvtap left promiscuous mode
device veth1_vlan left promiscuous mode
device veth0_vlan left promiscuous mode
------------[ cut here ]------------
WARNING: CPU: 1 PID: 155 at net/ipv6/route.c:4767 rt6_multipath_first_sibling net/ipv6/route.c:4689 [inline]
WARNING: CPU: 1 PID: 155 at net/ipv6/route.c:4767 rt6_multipath_rebalance+0x449/0x8a0 net/ipv6/route.c:4766
Modules linked in:
CPU: 1 PID: 155 Comm: kworker/u4:3 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Workqueue: netns cleanup_net
RIP: 0010:rt6_multipath_rebalance+0x449/0x8a0 net/ipv6/route.c:4767
Code: e8 8c 6c 1e f9 e9 1c fe ff ff 44 89 e1 80 e1 07 38 c1 0f 8c 85 fe ff ff 4c 89 e7 e8 51 6c 1e f9 e9 78 fe ff ff e8 b7 60 d9 f8 <0f> 0b eb 07 e8 ae 60 d9 f8 0f 0b 48 83 c4 10 5b 41 5c 41 5d 41 5e
RSP: 0018:ffffc90001ff70c0 EFLAGS: 00010293
RAX: ffffffff889fc019 RBX: ffff88805f70dc00 RCX: ffff88801d619dc0
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: dffffc0000000000 R08: ffff88807ba80ba7 R09: 1ffff1100f750174
R10: dffffc0000000000 R11: ffffed100f750175 R12: ffff88805f70dcb6
R13: ffff88805f70dc80 R14: 0000000000000000 R15: 1ffff1100bee1b90
FS:  0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c41751e CR3: 000000005f58e000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 fib6_ifdown+0x3ef/0x4a0 net/ipv6/route.c:4887
 fib6_clean_node+0x249/0x540 net/ipv6/ip6_fib.c:2190
 fib6_walk_continue+0x640/0x8c0 net/ipv6/ip6_fib.c:2115
 fib6_walk+0x149/0x290 net/ipv6/ip6_fib.c:2163
 fib6_clean_tree net/ipv6/ip6_fib.c:2243 [inline]
 __fib6_clean_all+0x25f/0x3c0 net/ipv6/ip6_fib.c:2259
 rt6_sync_down_dev net/ipv6/route.c:4915 [inline]
 rt6_disable_ip+0x127/0x6b0 net/ipv6/route.c:4920
 addrconf_ifdown+0x155/0x19c0 net/ipv6/addrconf.c:3775
 addrconf_notify+0x445/0xf00 net/ipv6/addrconf.c:-1
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
 call_netdevice_notifiers_extack net/core/dev.c:2074 [inline]
 call_netdevice_notifiers net/core/dev.c:2088 [inline]
 dev_close_many+0x29f/0x400 net/core/dev.c:1663
 unregister_netdevice_many+0x481/0x19f0 net/core/dev.c:11123
 default_device_exit_batch+0x364/0x3c0 net/core/dev.c:11680
 ops_exit_list net/core/net_namespace.c:177 [inline]
 cleanup_net+0x791/0xba0 net/core/net_namespace.c:635
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/08 11:13 linux-5.15.y 7b232985052f 4c131dc4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING in rt6_multipath_rebalance
* Struck through repros no longer work on HEAD.