Hello,
syzbot found the following issue on:
HEAD commit: 60a9e718726f Linux 6.6.106
git tree: linux-6.6.y
console output:
https://syzkaller.appspot.com/x/log.txt?x=17d84b62580000
kernel config:
https://syzkaller.appspot.com/x/.config?x=12606d4b8832c7e4
dashboard link:
https://syzkaller.appspot.com/bug?extid=99f7095084850a188d16
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image:
https://storage.googleapis.com/syzbot-assets/9490497c7bde/disk-60a9e718.raw.xz
vmlinux:
https://storage.googleapis.com/syzbot-assets/df4007be6667/vmlinux-60a9e718.xz
kernel image:
https://storage.googleapis.com/syzbot-assets/f38582a65e8f/bzImage-60a9e718.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by:
syzbot+99f709...@syzkaller.appspotmail.com
bridge0: received packet on team0 with own address as source address (addr:aa:aa:aa:aa:aa:20, vlan:0)
bridge0: received packet on team0 with own address as source address (addr:aa:aa:aa:aa:aa:20, vlan:0)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5788/1:b..l
rcu: (detected by 0, t=10502 jiffies, g=32185, q=280 ncpus=2)
task:syz-executor state:R running task stack:21736 pid:5788 ppid:5780 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5380 [inline]
__schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6866
preempt_schedule+0xab/0xc0 kernel/sched/core.c:6890
preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
__raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
_raw_spin_unlock+0x3a/0x40 kernel/locking/spinlock.c:186
spin_unlock include/linux/spinlock.h:391 [inline]
copy_pte_range mm/memory.c:1106 [inline]
copy_pmd_range mm/memory.c:1167 [inline]
copy_pud_range mm/memory.c:1204 [inline]
copy_p4d_range mm/memory.c:1228 [inline]
copy_page_range+0x2b7c/0x3600 mm/memory.c:1322
dup_mmap kernel/fork.c:764 [inline]
dup_mm kernel/fork.c:1692 [inline]
copy_mm+0x112a/0x1c20 kernel/fork.c:1741
copy_process+0x16d3/0x3d70 kernel/fork.c:2506
kernel_clone+0x21b/0x840 kernel/fork.c:2914
__do_sys_clone kernel/fork.c:3057 [inline]
__se_sys_clone kernel/fork.c:3041 [inline]
__x64_sys_clone+0x18c/0x1e0 kernel/fork.c:3041
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc177985413
RSP: 002b:00007ffc8206ebc8 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc177985413
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001
R10: 000055557d94f7d0 R11: 0000000000000246 R12: 0000000000000000
R13: 00000000000927c0 R14: 000000000004fe26 R15: 00007ffc8206ed60
</TASK>
rcu: rcu_preempt kthread starved for 4888 jiffies! g32185 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt state:R running task stack:26568 pid:17 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5380 [inline]
__schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
schedule+0xbd/0x170 kernel/sched/core.c:6773
schedule_timeout+0x160/0x280 kernel/time/timer.c:2167
rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667
rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1866
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 8770 Comm: syz.2.951 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:unwind_next_frame+0x1d1f/0x2970 arch/x86/kernel/unwind_orc.c:672
Code: 00 eb 05 e8 83 d0 4a 00 bf 01 00 00 00 e8 e9 ab 20 00 65 8b 1d 3a fa c8 7e 31 ff 89 de e8 19 d4 4a 00 85 db 0f 84 e6 02 00 00 <e8> 5c d0 4a 00 b0 01 e9 28 05 00 00 e8 50 d0 4a 00 48 8b 5c 24 58
RSP: 0018:ffffc900000073b8 EFLAGS: 00000202
RAX: ffffffff813abfd7 RBX: 0000000000000101 RCX: 0000000000000100
RDX: ffff88802aeada00 RSI: 0000000000000101 RDI: 0000000000000000
RBP: ffffc9000b8b7bd0 R08: ffff88802aeada00 R09: 0000000000000003
R10: 0000000000000004 R11: 0000000000000100 R12: ffffc90000007488
R13: dffffc0000000000 R14: ffffc9000b8b7be0 R15: ffffc90000007498
FS: 00007fbc116036c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f20b9073f98 CR3: 0000000023ef3000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000200000000300
DR3: 0000200000000300 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:522
____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:236
kasan_slab_free include/linux/kasan.h:164 [inline]
slab_free_hook mm/slub.c:1811 [inline]
slab_free_freelist_hook+0x130/0x1b0 mm/slub.c:1837
slab_free mm/slub.c:3830 [inline]
kmem_cache_free+0xf8/0x280 mm/slub.c:3852
kfree_skb include/linux/skbuff.h:1232 [inline]
ip6_mc_input+0xa7e/0xc70 net/ipv6/ip6_input.c:589
NF_HOOK+0x303/0x390 include/linux/netfilter.h:304
__netif_receive_skb_one_core net/core/dev.c:5608 [inline]
__netif_receive_skb+0xcc/0x290 net/core/dev.c:5722
process_backlog+0x380/0x6e0 net/core/dev.c:6050
__napi_poll+0xc0/0x460 net/core/dev.c:6612
napi_poll net/core/dev.c:6679 [inline]
net_rx_action+0x5ea/0xbf0 net/core/dev.c:6815
handle_softirqs+0x280/0x820 kernel/softirq.c:578
__do_softirq kernel/softirq.c:612 [inline]
invoke_softirq kernel/softirq.c:452 [inline]
__irq_exit_rcu+0xc7/0x190 kernel/softirq.c:661
irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:debug_lockdep_rcu_enabled+0xd/0x30 kernel/rcu/update.c:319
Code: 48 c7 c6 60 df aa 8a e8 91 ec e1 f6 0f 0b eb d1 cc cc cc cc cc cc cc cc cc cc cc cc cc f3 0f 1e fa 31 c0 83 3d 7f 76 dc 03 00 <74> 1d 83 3d f6 a9 dc 03 00 74 14 65 48 8b 0d 50 9a 95 75 31 c0 83
RSP: 0018:ffffc9000b8b78b8 EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffffc9000b8b0000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc9000b8b7a40
RBP: ffffc9000b8b7ab0 R08: ffffc9000b8b7a3f R09: 0000000000000000
R10: ffffc9000b8b7a30 R11: fffff52001716f48 R12: 0000000000000001
R13: ffff8880b8e00000 R14: dffffc0000000000 R15: 1ffff92001716f34
schedule_debug kernel/sched/core.c:5957 [inline]
__schedule+0x1c6/0x44d0 kernel/sched/core.c:6590
preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6866
preempt_schedule+0xab/0xc0 kernel/sched/core.c:6890
preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
_raw_spin_unlock_irq+0x40/0x50 kernel/locking/spinlock.c:202
task_work_run+0x191/0x250 kernel/task_work.c:235
get_signal+0x1235/0x1400 kernel/signal.c:2678
arch_do_signal_or_restart+0x96/0x780 arch/x86/kernel/signal.c:310
exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fbc1078eba9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fbc116030e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007fbc109d6098 RCX: 00007fbc1078eba9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fbc109d6098
RBP: 00007fbc109d6090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbc109d6128 R14: 00007ffd4269a230 R15: 00007ffd4269a318
</TASK>
net_ratelimit: 1003 callbacks suppressed
bridge0: received packet on team0 with own address as source address (addr:aa:aa:aa:aa:aa:20, vlan:0)
bridge0: received packet on team0 with own address as source address (addr:aa:aa:aa:aa:aa:20, vlan:0)
bridge0: received packet on team0 with own address as source address (addr:aa:aa:aa:aa:aa:20, vlan:0)
bridge0: received packet on team0 with own address as source address (addr:aa:aa:aa:aa:aa:20, vlan:0)
bridge0: received packet on team0 with own address as source address (addr:aa:aa:aa:aa:aa:20, vlan:0)
net_ratelimit: 5843 callbacks suppressed
bridge0: received packet on team0 with own address as source address (addr:aa:aa:aa:aa:aa:20, vlan:0)
bridge0: received packet on team0 with own address as source address (addr:aa:aa:aa:aa:aa:20, vlan:0)
bridge0: received packet on team0 with own address as source address (addr:aa:aa:aa:aa:aa:20, vlan:0)
bridge0: received packet on team0 with own address as source address (addr:aa:aa:aa:aa:aa:20, vlan:0)
bridge0: received packet on team0 with own address as source address (addr:aa:aa:aa:aa:aa:20, vlan:0)
---
This report is generated by a bot. It may contain errors.
See
https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at
syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup