rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-...!: (1 GPs behind) idle=d21/1/0x4000000000000000 softirq=6834/6837 fqs=1
(detected by 1, t=10502 jiffies, g=7445, q=757)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 14 Comm: ksoftirqd/0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:__kasan_check_read+0x2/0x10 mm/kasan/shadow.c:31
Code: 41 5d 41 5e 41 5f 5d c3 48 c7 c7 b6 a0 df 8b eb 0a 48 c7 c7 b2 a1 c5 8b 48 89 de e8 68 4c f7 07 31 ed eb d7 00 00 cc cc 89 f6 <48> 8b 0c 24 31 d2 e9 43 ef ff ff 0f 1f 00 89 f6 48 8b 0c 24 ba 01
RSP: 0018:ffffc90000007898 EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffff88813fe29dc0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff901ee0c0
RBP: 0000000000000000 R08: dffffc0000000000 R09: 1ffffffff203dc19
R10: dffffc0000000000 R11: fffffbfff203dc1a R12: 0000000000000001
R13: dffffc0000000000 R14: ffff88813fe2a900 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f33843e22f8 CR3: 00000000762a7000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
instrument_atomic_read include/linux/instrumented.h:71 [inline]
test_bit include/asm-generic/bitops/instrumented-non-atomic.h:134 [inline]
hlock_class kernel/locking/lockdep.c:197 [inline]
mark_lock+0x94/0x320 kernel/locking/lockdep.c:4569
mark_usage kernel/locking/lockdep.c:4483 [inline]
__lock_acquire+0xc1d/0x7b50 kernel/locking/lockdep.c:4966
lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xb0/0x100 kernel/locking/spinlock.c:162
debug_object_deactivate+0x63/0x380 lib/debugobjects.c:757
debug_hrtimer_deactivate kernel/time/hrtimer.c:415 [inline]
__run_hrtimer kernel/time/hrtimer.c:1653 [inline]
__hrtimer_run_queues+0x2c0/0xb60 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x397/0x8b0 kernel/time/hrtimer.c:1811
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
__sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:seqcount_lockdep_reader_access+0x196/0x1d0 include/linux/seqlock.h:106
Code: 00 4d 85 e4 75 16 e8 a9 09 10 00 eb 15 e8 a2 09 10 00 e8 ad 1c 57 08 4d 85 e4 74 ea e8 93 09 10 00 fb 48 c7 04 24 0e 36 e0 45 <4b> c7 04 3e 00 00 00 00 43 c7 44 3e 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc90000d377a0 EFLAGS: 00000246
RAX: ffffffff8168f7ed RBX: 0000000000000000 RCX: ffff88813fe29dc0
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90000d37848 R08: ffffffff901ee18f R09: 1ffffffff203dc31
R10: dffffc0000000000 R11: fffffbfff203dc32 R12: 0000000000000200
R13: dffffc0000000000 R14: 1ffff920001a6ef4 R15: dffffc0000000000
ktime_get+0x31/0x270 kernel/time/timekeeping.c:829
ktime_get_ns include/linux/timekeeping.h:154 [inline]
tcp_clock_ns include/net/tcp.h:775 [inline]
tcp_mstamp_refresh net/ipv4/tcp_output.c:55 [inline]
tcp_write_xmit+0x41/0x65c0 net/ipv4/tcp_output.c:2640
tcp_tsq_handler+0x11e/0x1f0 net/ipv4/tcp_output.c:1030
tcp_tasklet_func+0x3f2/0x480 net/ipv4/tcp_output.c:1062
tasklet_action_common+0x2ad/0x410 kernel/softirq.c:806
handle_softirqs+0x336/0x830 kernel/softirq.c:576
run_ksoftirqd+0xa4/0x100 kernel/softirq.c:943
smpboot_thread_fn+0x520/0x990 kernel/smpboot.c:164
kthread+0x42e/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
rcu: rcu_preempt kthread starved for 10497 jiffies! g7445 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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:28112 pid: 15 ppid: 2 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11c3/0x4350 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117
rcu_gp_fqs_loop+0x2be/0x11f0 kernel/rcu/tree.c:1972
rcu_gp_kthread+0x9a/0x370 kernel/rcu/tree.c:2145
kthread+0x42e/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 1
CPU: 1 PID: 20 Comm: ksoftirqd/1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487
print_other_cpu_stall+0x1110/0x1270 kernel/rcu/tree_stall.h:592
check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
rcu_pending kernel/rcu/tree.c:3936 [inline]
rcu_sched_clock_irq+0x845/0x1120 kernel/rcu/tree.c:2619
update_process_times+0x193/0x200 kernel/time/timer.c:2021
tick_sched_handle kernel/time/tick-sched.c:254 [inline]
tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x4b0/0xb60 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x397/0x8b0 kernel/time/hrtimer.c:1811
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
__sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
RIP: 0010:arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
RIP: 0010:kvm_wait+0x159/0x1b0 arch/x86/kernel/kvm.c:918
Code: 89 df 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 75 4b 0f b6 1f e8 c7 8d 4a 00 44 38 e3 75 10 66 90 0f 00 2d c9 e9 f3 08 fb f4 16 ff ff ff fb e9 10 ff ff ff e8 77 7a 8b 08 89 f9 80 e1 07 38
RSP: 0018:ffffc90000da6d60 EFLAGS: 00000246
RAX: aa4e55df865a4a00 RBX: 0000000000000003 RCX: aa4e55df865a4a00
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a4200
RBP: ffffc90000da6e10 R08: ffffffff901ee197 R09: 1ffffffff203dc32
R10: dffffc0000000000 R11: fffffbfff203dc33 R12: 0000000000000003
R13: dffffc0000000000 R14: dffffc0000000000 R15: 1ffff920001b4dac
pv_wait arch/x86/include/asm/paravirt.h:597 [inline]
pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline]
__pv_queued_spin_lock_slowpath+0x605/0x9b0 kernel/locking/qspinlock.c:508
pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:585 [inline]
queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51
queued_spin_lock include/asm-generic/qspinlock.h:85 [inline]
do_raw_spin_lock+0x265/0x2f0 kernel/locking/spinlock_debug.c:115
tcp_v4_rcv+0x25d2/0x2c80 net/ipv4/tcp_ipv4.c:2138
ip_protocol_deliver_rcu+0x38c/0x740 net/ipv4/ip_input.c:204
ip_local_deliver_finish+0x1d8/0x320 net/ipv4/ip_input.c:231
NF_HOOK+0x303/0x390 include/linux/netfilter.h:302
dst_input include/net/dst.h:462 [inline]
ip_sublist_rcv_finish net/ipv4/ip_input.c:577 [inline]
ip_list_rcv_finish net/ipv4/ip_input.c:628 [inline]
ip_sublist_rcv+0xa17/0xd10 net/ipv4/ip_input.c:636
ip_list_rcv+0x3e9/0x440 net/ipv4/ip_input.c:671
__netif_receive_skb_list_ptype net/core/dev.c:5594 [inline]
__netif_receive_skb_list_core+0x57e/0x770 net/core/dev.c:5642
__netif_receive_skb_list net/core/dev.c:5694 [inline]
netif_receive_skb_list_internal+0x898/0xbd0 net/core/dev.c:5785
gro_normal_list net/core/dev.c:5939 [inline]
napi_complete_done+0x37e/0x850 net/core/dev.c:6677
virtqueue_napi_complete drivers/net/virtio_net.c:357 [inline]
virtnet_poll+0x9b7/0xfb0 drivers/net/virtio_net.c:1627
__napi_poll+0xbb/0x430 net/core/dev.c:7101
napi_poll net/core/dev.c:7168 [inline]
net_rx_action+0x522/0xa80 net/core/dev.c:7258
handle_softirqs+0x336/0x830 kernel/softirq.c:576
run_ksoftirqd+0xa4/0x100 kernel/softirq.c:943
smpboot_thread_fn+0x520/0x990 kernel/smpboot.c:164
kthread+0x42e/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287