[v6.6] INFO: rcu detected stall in kthreadd (2)
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syzbot
Jan 27, 2026, 4:22:28 PM (22 hours ago) Jan 27
to syzkaller...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: cbb31f77b879 Linux 6.6.121
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1717a802580000
kernel config: https://syzkaller.appspot.com/x/.config?x=2a950bf7c0bff9f9
dashboard link: https://syzkaller.appspot.com/bug?extid=c557e44005febbf6663e
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/487f8544b25c/disk-cbb31f77.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/129a28b457e8/vmlinux-cbb31f77.xz
kernel image: https://storage.googleapis.com/syzbot-assets/47e034f9408f/bzImage-cbb31f77.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c557e4...@syzkaller.appspotmail.com
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5766/1:b..l P2/1:b..l
rcu: (detected by 0, t=10503 jiffies, g=70353, q=186 ncpus=2)
task:kthreadd state:R running task stack:26152 pid:2 ppid:0 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5381 [inline]
__schedule+0x1553/0x45a0 kernel/sched/core.c:6700
preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7010
irqentry_exit+0x67/0x70 kernel/entry/common.c:438
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:check_kcov_mode kernel/kcov.c:184 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x30/0x60 kernel/kcov.c:216
Code: 04 24 65 48 8b 0d 90 a2 7c 7e 65 8b 15 91 a2 7c 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 1c 16 00 00 00 74 2c <8b> 91 f8 15 00 00 83 fa 02 75 21 48 8b 91 00 16 00 00 48 8b 32 48
RSP: 0018:ffffc90000076f68 EFLAGS: 00000246
RAX: ffffffff813b3647 RBX: ffffc900000770a8 RCX: ffff88801a671e00
RDX: 0000000000000000 RSI: ffffc90000077130 RDI: ffffc900000770a8
RBP: ffffc90000077138 R08: ffff88801a671e00 R09: 0000000000000003
R10: 0000000000000004 R11: 0000000000000000 R12: ffffc900000770a8
R13: dffffc0000000000 R14: 1ffff9200000ee15 R15: ffffc900000770b0
unwind_next_frame+0x27/0x2970 arch/x86/kernel/unwind_orc.c:469
__unwind_start+0x66a/0x7e0 arch/x86/kernel/unwind_orc.c:760
unwind_start arch/x86/include/asm/unwind.h:64 [inline]
arch_stack_walk+0xf8/0x190 arch/x86/kernel/stacktrace.c:24
stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
save_stack+0x125/0x230 mm/page_owner.c:128
__reset_page_owner+0x4e/0x190 mm/page_owner.c:149
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1154 [inline]
free_unref_page_prepare+0x7b2/0x8c0 mm/page_alloc.c:2336
free_unref_page+0x32/0x2e0 mm/page_alloc.c:2429
discard_slab mm/slub.c:2127 [inline]
__unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
put_cpu_partial+0x17c/0x250 mm/slub.c:2743
__slab_free+0x319/0x400 mm/slub.c:3700
qlink_free mm/kasan/quarantine.c:166 [inline]
qlist_free_all+0x75/0xd0 mm/kasan/quarantine.c:185
kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x6e/0x4b0 mm/slab.h:767
slab_alloc_node mm/slub.c:3495 [inline]
__kmem_cache_alloc_node+0x13a/0x250 mm/slub.c:3534
kmalloc_node_trace+0x26/0xe0 mm/slab_common.c:1111
kmalloc_node include/linux/slab.h:616 [inline]
kzalloc_node include/linux/slab.h:732 [inline]
__get_vm_area_node+0x125/0x370 mm/vmalloc.c:2613
__vmalloc_node_range+0x36e/0x1330 mm/vmalloc.c:3299
alloc_thread_stack_node kernel/fork.c:310 [inline]
dup_task_struct+0x3d0/0x7c0 kernel/fork.c:1124
copy_process+0x586/0x3d80 kernel/fork.c:2331
kernel_clone+0x24b/0x8a0 kernel/fork.c:2914
kernel_thread+0x13f/0x1b0 kernel/fork.c:2976
create_kthread kernel/kthread.c:411 [inline]
kthreadd+0x57f/0x750 kernel/kthread.c:766
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>
task:syz-executor state:R running task stack:24232 pid:5766 ppid:5758 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5381 [inline]
__schedule+0x1553/0x45a0 kernel/sched/core.c:6700
preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6867
preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6891
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]
zap_pte_range mm/memory.c:1523 [inline]
zap_pmd_range mm/memory.c:1571 [inline]
zap_pud_range mm/memory.c:1600 [inline]
zap_p4d_range mm/memory.c:1621 [inline]
unmap_page_range+0x2315/0x3000 mm/memory.c:1642
unmap_vmas+0x286/0x3f0 mm/memory.c:1732
exit_mmap+0x238/0xb90 mm/mmap.c:3302
__mmput+0x118/0x3c0 kernel/fork.c:1355
exit_mm+0x1f2/0x2c0 kernel/exit.c:569
do_exit+0x8dd/0x2460 kernel/exit.c:870
do_group_exit+0x21b/0x2d0 kernel/exit.c:1024
get_signal+0x12fc/0x13f0 kernel/signal.c:2902
arch_do_signal_or_restart+0xc2/0x800 arch/x86/kernel/signal.c:310
exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
exit_to_user_mode_prepare+0xee/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+0x61/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fe94e5560d7
RSP: 002b:00007ffd60c5ade0 EFLAGS: 00000202 ORIG_RAX: 000000000000003d
RAX: fffffffffffffe00 RBX: 0000555582a4a500 RCX: 00007fe94e5560d7
RDX: 0000000040000000 RSI: 00007ffd60c5ae3c RDI: ffffffffffffffff
RBP: 00007ffd60c5ae3c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000008
R13: 0000000000000003 R14: 00007ffd60c5b098 R15: 0000000000000000
</TASK>
rcu: rcu_preempt kthread starved for 638 jiffies! g70353 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:26760 pid:17 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5381 [inline]
__schedule+0x1553/0x45a0 kernel/sched/core.c:6700
schedule+0xbd/0x170 kernel/sched/core.c:6774
schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
rcu_gp_fqs_loop+0x313/0x1590 kernel/rcu/tree.c:1667
rcu_gp_kthread+0x9d/0x3b0 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: 11149 Comm: syz.2.1883 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:check_kcov_mode kernel/kcov.c:182 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x27/0x60 kernel/kcov.c:216
Code: cc cc cc f3 0f 1e fa 48 8b 04 24 65 48 8b 0d 90 a2 7c 7e 65 8b 15 91 a2 7c 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 <83> b9 1c 16 00 00 00 74 2c 8b 91 f8 15 00 00 83 fa 02 75 21 48 8b
RSP: 0018:ffffc90000006778 EFLAGS: 00000246
RAX: ffffffff893e412d RBX: ffff88805c745cb8 RCX: ffff88807d0e1e00
RDX: 0000000000000100 RSI: 00000000fffffffd RDI: 00000000fffffffd
RBP: 1ffff1100b8e8b97 R08: ffffc90000006a80 R09: ffffc90000006a90
R10: ffffc900000068e0 R11: fffff52000000d1e R12: dffffc0000000000
R13: 0000000000000003 R14: 1ffff1100b8e8b99 R15: 00000000fffffffd
FS: 00007fcbd8efa6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000180 CR3: 000000007624d000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
find_match+0x1dd/0xc80 net/ipv6/route.c:791
__find_rr_leaf+0x249/0x760 net/ipv6/route.c:870
find_rr_leaf net/ipv6/route.c:891 [inline]
rt6_select net/ipv6/route.c:935 [inline]
fib6_table_lookup+0x3b5/0xa80 net/ipv6/route.c:2231
ip6_pol_route+0x239/0x1210 net/ipv6/route.c:2267
pol_lookup_func include/net/ip6_fib.h:622 [inline]
fib6_rule_lookup+0x20c/0x570 net/ipv6/fib6_rules.c:116
ip6_route_input_lookup net/ipv6/route.c:2336 [inline]
ip6_route_input+0x732/0xa50 net/ipv6/route.c:2632
ip6_rcv_finish+0x143/0x230 net/ipv6/ip6_input.c:77
ip_sabotage_in+0x1f4/0x280 net/bridge/br_netfilter_hooks.c:1001
nf_hook_entry_hookfn include/linux/netfilter.h:144 [inline]
nf_hook_slow+0xbd/0x200 net/netfilter/core.c:626
nf_hook include/linux/netfilter.h:259 [inline]
NF_HOOK+0x21d/0x3b0 include/linux/netfilter.h:302
__netif_receive_skb_one_core net/core/dev.c:5638 [inline]
__netif_receive_skb+0xcc/0x290 net/core/dev.c:5752
netif_receive_skb_internal net/core/dev.c:5838 [inline]
netif_receive_skb+0x1bc/0x720 net/core/dev.c:5897
NF_HOOK+0x9e/0x3a0 include/linux/netfilter.h:304
br_handle_frame_finish+0x14b9/0x19b0 net/bridge/br_input.c:221
br_nf_hook_thresh+0x3cd/0x4a0 net/bridge/br_netfilter_hooks.c:1184
br_nf_pre_routing_finish_ipv6+0x9dc/0xd00 net/bridge/br_netfilter_ipv6.c:-1
NF_HOOK include/linux/netfilter.h:304 [inline]
br_nf_pre_routing_ipv6+0x349/0x6b0 net/bridge/br_netfilter_ipv6.c:184
nf_hook_entry_hookfn include/linux/netfilter.h:144 [inline]
nf_hook_bridge_pre net/bridge/br_input.c:277 [inline]
br_handle_frame+0x96b/0x14e0 net/bridge/br_input.c:424
__netif_receive_skb_core+0xfab/0x3af0 net/core/dev.c:5532
__netif_receive_skb_one_core net/core/dev.c:5636 [inline]
__netif_receive_skb+0x74/0x290 net/core/dev.c:5752
process_backlog+0x396/0x700 net/core/dev.c:6080
__napi_poll+0xc0/0x460 net/core/dev.c:6642
napi_poll net/core/dev.c:6709 [inline]
net_rx_action+0x616/0xc50 net/core/dev.c:6846
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+0xd3/0x190 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:preempt_schedule+0xc0/0xd0 kernel/sched/core.c:-1
Code: 0e 36 e0 45 4a c7 04 33 00 00 00 00 65 48 8b 04 25 28 00 00 00 48 3b 44 24 58 75 10 48 8d 65 f0 5b 41 5e 5d c3 e8 10 00 00 00 <eb> d0 e8 19 bc f7 ff 66 0f 1f 84 00 00 00 00 00 41 57 41 56 53 49
RSP: 0018:ffffc90003116e60 EFLAGS: 00000246
RAX: 1ffff1100fa1c3c0 RBX: 1ffff92000622dcc RCX: ffffffff815d6286
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffff8880768a5f00
RBP: ffffc90003116ee8 R08: ffff8880768a5f03 R09: 1ffff1100ed14be0
R10: dffffc0000000000 R11: ffffed100ed14be1 R12: ffffc90003117088
R13: dffffc0000000000 R14: dffffc0000000000 R15: ffffc90003117098
preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
unwind_next_frame+0x200f/0x2970 arch/x86/kernel/unwind_orc.c:672
__unwind_start+0x66a/0x7e0 arch/x86/kernel/unwind_orc.c:760
unwind_start arch/x86/include/asm/unwind.h:64 [inline]
arch_stack_walk+0xf8/0x190 arch/x86/kernel/stacktrace.c:24
stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
save_stack+0x125/0x230 mm/page_owner.c:128
__reset_page_owner+0x4e/0x190 mm/page_owner.c:149
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1154 [inline]
free_unref_page_prepare+0x7b2/0x8c0 mm/page_alloc.c:2336
free_unref_page+0x32/0x2e0 mm/page_alloc.c:2429
discard_slab mm/slub.c:2127 [inline]
__unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
put_cpu_partial+0x17c/0x250 mm/slub.c:2743
__slab_free+0x319/0x400 mm/slub.c:3700
qlink_free mm/kasan/quarantine.c:166 [inline]
qlist_free_all+0x75/0xd0 mm/kasan/quarantine.c:185
kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x6e/0x4b0 mm/slab.h:767
slab_alloc_node mm/slub.c:3495 [inline]
slab_alloc mm/slub.c:3503 [inline]
__kmem_cache_alloc_lru mm/slub.c:3510 [inline]
kmem_cache_alloc+0x11a/0x2d0 mm/slub.c:3519
kmem_cache_zalloc include/linux/slab.h:711 [inline]
__kernfs_new_node+0xe5/0x810 fs/kernfs/dir.c:624
kernfs_new_node+0x14c/0x260 fs/kernfs/dir.c:700
__kernfs_create_file+0x4b/0x2e0 fs/kernfs/file.c:1068
sysfs_add_file_mode_ns+0x238/0x300 fs/sysfs/file.c:294
create_files fs/sysfs/group.c:64 [inline]
internal_create_group+0x434/0xd10 fs/sysfs/group.c:152
internal_create_groups fs/sysfs/group.c:192 [inline]
sysfs_create_groups+0x59/0x120 fs/sysfs/group.c:218
device_add_groups drivers/base/core.c:2785 [inline]
device_add_attrs+0x1b2/0x830 drivers/base/core.c:2905
device_add+0x528/0xc20 drivers/base/core.c:3637
netdev_register_kobject+0x188/0x320 net/core/net-sysfs.c:2042
register_netdevice+0x12ef/0x1b90 net/core/dev.c:10311
tun_set_iff+0x848/0xed0 drivers/net/tun.c:2862
__tun_chr_ioctl+0x7ee/0x2000 drivers/net/tun.c:3131
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fcbd7f9aeb9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fcbd8efa028 EFLAGS: 00000246
ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fcbd8215fa0 RCX: 00007fcbd7f9aeb9
RDX: 0000200000000080 RSI: 00000000400454ca RDI: 0000000000000008
RBP: 00007fcbd8008c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fcbd8216038 R14: 00007fcbd8215fa0 R15: 00007fff5dfdfdb8
</TASK>
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
net_ratelimit: 1485 callbacks suppressed
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
---
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If the report is already addressed, let syzbot know by replying with:
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syzbot found the following issue on:
HEAD commit: cbb31f77b879 Linux 6.6.121
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1717a802580000
kernel config: https://syzkaller.appspot.com/x/.config?x=2a950bf7c0bff9f9
dashboard link: https://syzkaller.appspot.com/bug?extid=c557e44005febbf6663e
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/487f8544b25c/disk-cbb31f77.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/129a28b457e8/vmlinux-cbb31f77.xz
kernel image: https://storage.googleapis.com/syzbot-assets/47e034f9408f/bzImage-cbb31f77.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c557e4...@syzkaller.appspotmail.com
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5766/1:b..l P2/1:b..l
rcu: (detected by 0, t=10503 jiffies, g=70353, q=186 ncpus=2)
task:kthreadd state:R running task stack:26152 pid:2 ppid:0 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5381 [inline]
__schedule+0x1553/0x45a0 kernel/sched/core.c:6700
preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7010
irqentry_exit+0x67/0x70 kernel/entry/common.c:438
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:check_kcov_mode kernel/kcov.c:184 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x30/0x60 kernel/kcov.c:216
Code: 04 24 65 48 8b 0d 90 a2 7c 7e 65 8b 15 91 a2 7c 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 1c 16 00 00 00 74 2c <8b> 91 f8 15 00 00 83 fa 02 75 21 48 8b 91 00 16 00 00 48 8b 32 48
RSP: 0018:ffffc90000076f68 EFLAGS: 00000246
RAX: ffffffff813b3647 RBX: ffffc900000770a8 RCX: ffff88801a671e00
RDX: 0000000000000000 RSI: ffffc90000077130 RDI: ffffc900000770a8
RBP: ffffc90000077138 R08: ffff88801a671e00 R09: 0000000000000003
R10: 0000000000000004 R11: 0000000000000000 R12: ffffc900000770a8
R13: dffffc0000000000 R14: 1ffff9200000ee15 R15: ffffc900000770b0
unwind_next_frame+0x27/0x2970 arch/x86/kernel/unwind_orc.c:469
__unwind_start+0x66a/0x7e0 arch/x86/kernel/unwind_orc.c:760
unwind_start arch/x86/include/asm/unwind.h:64 [inline]
arch_stack_walk+0xf8/0x190 arch/x86/kernel/stacktrace.c:24
stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
save_stack+0x125/0x230 mm/page_owner.c:128
__reset_page_owner+0x4e/0x190 mm/page_owner.c:149
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1154 [inline]
free_unref_page_prepare+0x7b2/0x8c0 mm/page_alloc.c:2336
free_unref_page+0x32/0x2e0 mm/page_alloc.c:2429
discard_slab mm/slub.c:2127 [inline]
__unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
put_cpu_partial+0x17c/0x250 mm/slub.c:2743
__slab_free+0x319/0x400 mm/slub.c:3700
qlink_free mm/kasan/quarantine.c:166 [inline]
qlist_free_all+0x75/0xd0 mm/kasan/quarantine.c:185
kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x6e/0x4b0 mm/slab.h:767
slab_alloc_node mm/slub.c:3495 [inline]
__kmem_cache_alloc_node+0x13a/0x250 mm/slub.c:3534
kmalloc_node_trace+0x26/0xe0 mm/slab_common.c:1111
kmalloc_node include/linux/slab.h:616 [inline]
kzalloc_node include/linux/slab.h:732 [inline]
__get_vm_area_node+0x125/0x370 mm/vmalloc.c:2613
__vmalloc_node_range+0x36e/0x1330 mm/vmalloc.c:3299
alloc_thread_stack_node kernel/fork.c:310 [inline]
dup_task_struct+0x3d0/0x7c0 kernel/fork.c:1124
copy_process+0x586/0x3d80 kernel/fork.c:2331
kernel_clone+0x24b/0x8a0 kernel/fork.c:2914
kernel_thread+0x13f/0x1b0 kernel/fork.c:2976
create_kthread kernel/kthread.c:411 [inline]
kthreadd+0x57f/0x750 kernel/kthread.c:766
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>
task:syz-executor state:R running task stack:24232 pid:5766 ppid:5758 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5381 [inline]
__schedule+0x1553/0x45a0 kernel/sched/core.c:6700
preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6867
preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6891
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]
zap_pte_range mm/memory.c:1523 [inline]
zap_pmd_range mm/memory.c:1571 [inline]
zap_pud_range mm/memory.c:1600 [inline]
zap_p4d_range mm/memory.c:1621 [inline]
unmap_page_range+0x2315/0x3000 mm/memory.c:1642
unmap_vmas+0x286/0x3f0 mm/memory.c:1732
exit_mmap+0x238/0xb90 mm/mmap.c:3302
__mmput+0x118/0x3c0 kernel/fork.c:1355
exit_mm+0x1f2/0x2c0 kernel/exit.c:569
do_exit+0x8dd/0x2460 kernel/exit.c:870
do_group_exit+0x21b/0x2d0 kernel/exit.c:1024
get_signal+0x12fc/0x13f0 kernel/signal.c:2902
arch_do_signal_or_restart+0xc2/0x800 arch/x86/kernel/signal.c:310
exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
exit_to_user_mode_prepare+0xee/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+0x61/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fe94e5560d7
RSP: 002b:00007ffd60c5ade0 EFLAGS: 00000202 ORIG_RAX: 000000000000003d
RAX: fffffffffffffe00 RBX: 0000555582a4a500 RCX: 00007fe94e5560d7
RDX: 0000000040000000 RSI: 00007ffd60c5ae3c RDI: ffffffffffffffff
RBP: 00007ffd60c5ae3c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000008
R13: 0000000000000003 R14: 00007ffd60c5b098 R15: 0000000000000000
</TASK>
rcu: rcu_preempt kthread starved for 638 jiffies! g70353 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:26760 pid:17 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5381 [inline]
__schedule+0x1553/0x45a0 kernel/sched/core.c:6700
schedule+0xbd/0x170 kernel/sched/core.c:6774
schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
rcu_gp_fqs_loop+0x313/0x1590 kernel/rcu/tree.c:1667
rcu_gp_kthread+0x9d/0x3b0 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: 11149 Comm: syz.2.1883 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:check_kcov_mode kernel/kcov.c:182 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x27/0x60 kernel/kcov.c:216
Code: cc cc cc f3 0f 1e fa 48 8b 04 24 65 48 8b 0d 90 a2 7c 7e 65 8b 15 91 a2 7c 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 <83> b9 1c 16 00 00 00 74 2c 8b 91 f8 15 00 00 83 fa 02 75 21 48 8b
RSP: 0018:ffffc90000006778 EFLAGS: 00000246
RAX: ffffffff893e412d RBX: ffff88805c745cb8 RCX: ffff88807d0e1e00
RDX: 0000000000000100 RSI: 00000000fffffffd RDI: 00000000fffffffd
RBP: 1ffff1100b8e8b97 R08: ffffc90000006a80 R09: ffffc90000006a90
R10: ffffc900000068e0 R11: fffff52000000d1e R12: dffffc0000000000
R13: 0000000000000003 R14: 1ffff1100b8e8b99 R15: 00000000fffffffd
FS: 00007fcbd8efa6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000180 CR3: 000000007624d000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
find_match+0x1dd/0xc80 net/ipv6/route.c:791
__find_rr_leaf+0x249/0x760 net/ipv6/route.c:870
find_rr_leaf net/ipv6/route.c:891 [inline]
rt6_select net/ipv6/route.c:935 [inline]
fib6_table_lookup+0x3b5/0xa80 net/ipv6/route.c:2231
ip6_pol_route+0x239/0x1210 net/ipv6/route.c:2267
pol_lookup_func include/net/ip6_fib.h:622 [inline]
fib6_rule_lookup+0x20c/0x570 net/ipv6/fib6_rules.c:116
ip6_route_input_lookup net/ipv6/route.c:2336 [inline]
ip6_route_input+0x732/0xa50 net/ipv6/route.c:2632
ip6_rcv_finish+0x143/0x230 net/ipv6/ip6_input.c:77
ip_sabotage_in+0x1f4/0x280 net/bridge/br_netfilter_hooks.c:1001
nf_hook_entry_hookfn include/linux/netfilter.h:144 [inline]
nf_hook_slow+0xbd/0x200 net/netfilter/core.c:626
nf_hook include/linux/netfilter.h:259 [inline]
NF_HOOK+0x21d/0x3b0 include/linux/netfilter.h:302
__netif_receive_skb_one_core net/core/dev.c:5638 [inline]
__netif_receive_skb+0xcc/0x290 net/core/dev.c:5752
netif_receive_skb_internal net/core/dev.c:5838 [inline]
netif_receive_skb+0x1bc/0x720 net/core/dev.c:5897
NF_HOOK+0x9e/0x3a0 include/linux/netfilter.h:304
br_handle_frame_finish+0x14b9/0x19b0 net/bridge/br_input.c:221
br_nf_hook_thresh+0x3cd/0x4a0 net/bridge/br_netfilter_hooks.c:1184
br_nf_pre_routing_finish_ipv6+0x9dc/0xd00 net/bridge/br_netfilter_ipv6.c:-1
NF_HOOK include/linux/netfilter.h:304 [inline]
br_nf_pre_routing_ipv6+0x349/0x6b0 net/bridge/br_netfilter_ipv6.c:184
nf_hook_entry_hookfn include/linux/netfilter.h:144 [inline]
nf_hook_bridge_pre net/bridge/br_input.c:277 [inline]
br_handle_frame+0x96b/0x14e0 net/bridge/br_input.c:424
__netif_receive_skb_core+0xfab/0x3af0 net/core/dev.c:5532
__netif_receive_skb_one_core net/core/dev.c:5636 [inline]
__netif_receive_skb+0x74/0x290 net/core/dev.c:5752
process_backlog+0x396/0x700 net/core/dev.c:6080
__napi_poll+0xc0/0x460 net/core/dev.c:6642
napi_poll net/core/dev.c:6709 [inline]
net_rx_action+0x616/0xc50 net/core/dev.c:6846
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+0xd3/0x190 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:preempt_schedule+0xc0/0xd0 kernel/sched/core.c:-1
Code: 0e 36 e0 45 4a c7 04 33 00 00 00 00 65 48 8b 04 25 28 00 00 00 48 3b 44 24 58 75 10 48 8d 65 f0 5b 41 5e 5d c3 e8 10 00 00 00 <eb> d0 e8 19 bc f7 ff 66 0f 1f 84 00 00 00 00 00 41 57 41 56 53 49
RSP: 0018:ffffc90003116e60 EFLAGS: 00000246
RAX: 1ffff1100fa1c3c0 RBX: 1ffff92000622dcc RCX: ffffffff815d6286
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffff8880768a5f00
RBP: ffffc90003116ee8 R08: ffff8880768a5f03 R09: 1ffff1100ed14be0
R10: dffffc0000000000 R11: ffffed100ed14be1 R12: ffffc90003117088
R13: dffffc0000000000 R14: dffffc0000000000 R15: ffffc90003117098
preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
unwind_next_frame+0x200f/0x2970 arch/x86/kernel/unwind_orc.c:672
__unwind_start+0x66a/0x7e0 arch/x86/kernel/unwind_orc.c:760
unwind_start arch/x86/include/asm/unwind.h:64 [inline]
arch_stack_walk+0xf8/0x190 arch/x86/kernel/stacktrace.c:24
stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
save_stack+0x125/0x230 mm/page_owner.c:128
__reset_page_owner+0x4e/0x190 mm/page_owner.c:149
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1154 [inline]
free_unref_page_prepare+0x7b2/0x8c0 mm/page_alloc.c:2336
free_unref_page+0x32/0x2e0 mm/page_alloc.c:2429
discard_slab mm/slub.c:2127 [inline]
__unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
put_cpu_partial+0x17c/0x250 mm/slub.c:2743
__slab_free+0x319/0x400 mm/slub.c:3700
qlink_free mm/kasan/quarantine.c:166 [inline]
qlist_free_all+0x75/0xd0 mm/kasan/quarantine.c:185
kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x6e/0x4b0 mm/slab.h:767
slab_alloc_node mm/slub.c:3495 [inline]
slab_alloc mm/slub.c:3503 [inline]
__kmem_cache_alloc_lru mm/slub.c:3510 [inline]
kmem_cache_alloc+0x11a/0x2d0 mm/slub.c:3519
kmem_cache_zalloc include/linux/slab.h:711 [inline]
__kernfs_new_node+0xe5/0x810 fs/kernfs/dir.c:624
kernfs_new_node+0x14c/0x260 fs/kernfs/dir.c:700
__kernfs_create_file+0x4b/0x2e0 fs/kernfs/file.c:1068
sysfs_add_file_mode_ns+0x238/0x300 fs/sysfs/file.c:294
create_files fs/sysfs/group.c:64 [inline]
internal_create_group+0x434/0xd10 fs/sysfs/group.c:152
internal_create_groups fs/sysfs/group.c:192 [inline]
sysfs_create_groups+0x59/0x120 fs/sysfs/group.c:218
device_add_groups drivers/base/core.c:2785 [inline]
device_add_attrs+0x1b2/0x830 drivers/base/core.c:2905
device_add+0x528/0xc20 drivers/base/core.c:3637
netdev_register_kobject+0x188/0x320 net/core/net-sysfs.c:2042
register_netdevice+0x12ef/0x1b90 net/core/dev.c:10311
tun_set_iff+0x848/0xed0 drivers/net/tun.c:2862
__tun_chr_ioctl+0x7ee/0x2000 drivers/net/tun.c:3131
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fcbd7f9aeb9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fcbd8efa028 EFLAGS: 00000246
ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fcbd8215fa0 RCX: 00007fcbd7f9aeb9
RDX: 0000200000000080 RSI: 00000000400454ca RDI: 0000000000000008
RBP: 00007fcbd8008c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fcbd8216038 R14: 00007fcbd8215fa0 R15: 00007fff5dfdfdb8
</TASK>
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
net_ratelimit: 1485 callbacks suppressed
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
---
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