syz_tun: tun_net_xmit 42
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-...!: (1 GPs behind) idle=853/1/0x4000000000000002 softirq=132846/132847 fqs=734
(detected by 1, t=10502 jiffies, g=198293, q=1175)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 16861 Comm: syz.5.14312 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__perf_event_account_interrupt+0x1/0x280 kernel/events/core.c:9427
Code: 1f 84 00 00 00 00 00 66 90 53 48 89 fb e8 17 a6 e0 ff 48 89 df be 01 00 00 00 5b eb 0c 66 2e 0f 1f 84 00 00 00 00 00 66 90 55 <41> 57 41 56 41 55 41 54 53 41 89 f6 48 89 fb 49 bd 00 00 00 00 00
RSP: 0018:ffffc900035ef1c0 EFLAGS: 00000006
RAX: ffffffff819871d6 RBX: ffff88804e6811e8 RCX: ffff888025ca8000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88804e6811e8
RBP: ffff88804e681658 R08: ffff88804e68165b R09: 1ffff11009cd02cb
R10: dffffc0000000000 R11: ffffed1009cd02cc R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000005 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbfb93d192c CR3: 00000000636c6000 CR4: 00000000003506f0
DR0: 0000200000000880 DR1: 0000200000000300 DR2: 0000200000000300
DR3: 0000200000000300 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
__perf_event_overflow+0x9a/0x550 kernel/events/core.c:9484
perf_swevent_overflow kernel/events/core.c:9601 [inline]
perf_swevent_event+0x4b8/0x540 kernel/events/core.c:9639
perf_tp_event+0x324/0xbe0 kernel/events/core.c:10057
perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10031
perf_trace_preemptirq_template+0x2aa/0x360 include/trace/events/preemptirq.h:14
trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40
trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44
asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:rcu_read_unlock_special+0x7f/0x4a0 kernel/rcu/tree_plugin.h:674
Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 42 0b 9d 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc900035ef720 EFLAGS: 00000206
RAX: 700845484b949f00 RBX: 1ffff920006bdee8 RCX: 700845484b949f00
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a48c0
RBP: ffffc900035ef7f0 R08: ffffffff901f10c7 R09: 1ffffffff203e218
R10: dffffc0000000000 R11: fffffbfff203e219 R12: ffffffff8c323400
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
__rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
rcu_read_unlock include/linux/rcupdate.h:772 [inline]
__unlock_page_memcg+0xea/0x100 mm/memcontrol.c:2093
zap_pte_range mm/memory.c:1384 [inline]
zap_pmd_range mm/memory.c:1505 [inline]
zap_pud_range mm/memory.c:1534 [inline]
zap_p4d_range mm/memory.c:1555 [inline]
unmap_page_range+0xee4/0x2410 mm/memory.c:1576
unmap_vmas+0x131/0x250 mm/memory.c:1653
exit_mmap+0x3b9/0x640 mm/mmap.c:3216
__mmput+0x115/0x390 kernel/fork.c:1133
exit_mm+0x632/0x7b0 kernel/exit.c:557
do_exit+0x5b8/0x2110 kernel/exit.c:877
do_group_exit+0x12c/0x2f0 kernel/exit.c:1004
__do_sys_exit_group kernel/exit.c:1015 [inline]
__se_sys_exit_group kernel/exit.c:1013 [inline]
__x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1013
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fe4d18eb159
Code: Unable to access opcode bytes at RIP 0x7fe4d18eb12f.
RSP: 002b:00007ffe7834e308 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe4d18eb159
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffe7834e36c R08: 0000000000000000 R09: 00000000000927c0
R10: 0000000000000006 R11: 0000000000000246 R12: 00000000000001c4
R13: 00000000000927c0 R14: 00000000001a93e7 R15: 00007ffe7834e3c0
rcu: rcu_preempt kthread starved for 9033 jiffies! g198293 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:27216 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: 11418 Comm: kworker/u4:22 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: writeback wb_workfn (flush-8:0)
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 87 96 4a 00 44 38 e3 75 10 66 90 0f 00 2d c9 d9 f3 08 fb f4 16 ff ff ff fb e9 10 ff ff ff e8 d7 8a 8c 08 89 f9 80 e1 07 38
RSP: 0018:ffffc9000397e5a0 EFLAGS: 00000246
RAX: fe3b27ae54eee900 RBX: 0000000000000003 RCX: fe3b27ae54eee900
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a48c0
RBP: ffffc9000397e650 R08: ffffffff901f10c7 R09: 1ffffffff203e218
R10: dffffc0000000000 R11: fffffbfff203e219 R12: 0000000000000003
R13: dffffc0000000000 R14: dffffc0000000000 R15: 1ffff9200072fcb4
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
page_vma_mapped_walk+0x13ee/0x16e0 mm/page_vma_mapped.c:-1
page_mkclean_one+0x17d/0x3e0 mm/rmap.c:926
rmap_walk_file+0x407/0x610 mm/rmap.c:2378
rmap_walk mm/rmap.c:2396 [inline]
page_mkclean+0x2f5/0x400 mm/rmap.c:1006
clear_page_dirty_for_io+0x3f9/0x9f0 mm/page-writeback.c:2749
mpage_submit_page+0x8a/0x210 fs/ext4/inode.c:2095
mpage_process_page_bufs+0x6c6/0x8a0 fs/ext4/inode.c:2229
mpage_prepare_extent_to_map+0xc48/0x1080 fs/ext4/inode.c:2657
ext4_writepages+0x9bb/0x2d40 fs/ext4/inode.c:2785
do_writepages+0x493/0x700 mm/page-writeback.c:2386
__writeback_single_inode+0x153/0xda0 fs/fs-writeback.c:1657
writeback_sb_inodes+0xaaa/0x1750 fs/fs-writeback.c:1940
__writeback_inodes_wb+0x12a/0x3f0 fs/fs-writeback.c:2011
wb_writeback+0x45e/0xbc0 fs/fs-writeback.c:2116
wb_check_old_data_flush fs/fs-writeback.c:2216 [inline]
wb_do_writeback fs/fs-writeback.c:2269 [inline]
wb_workfn+0xb15/0xf20 fs/fs-writeback.c:2298
process_one_work+0x867/0xff0 kernel/workqueue.c:2310
worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
kthread+0x42e/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287