rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-...!: (1 GPs behind) idle=7e1/1/0x4000000000000002 softirq=7237/7240 fqs=2
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P1271/1:b..l
(detected by 1, t=10505 jiffies, g=8017, q=381)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4674 Comm: syz.4.119 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:check_preemption_disabled+0x4b/0x110 lib/smp_processor_id.c:55
Code: 0d a2 2a 41 76 f7 c1 ff ff ff 7f 74 1f 65 48 8b 0c 25 28 00 00 00 48 3b 4c 24 08 0f 85 c4 00 00 00 48 83 c4 10 5b 41 5e 41 5f <5d> c3 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 74
RSP: 0018:ffffc900031df2c0 EFLAGS: 00000082
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 77c0e67949cbb700
RDX: 0000000000000000 RSI: ffffffff8a7a48a0 RDI: ffffffff8a7a4860
RBP: ffffc900031df430 R08: ffffc900031df3b7 R09: ffffc900031df3a0
R10: dffffc0000000000 R11: fffff5200063be77 R12: 1ffff9200063be70
R13: ffffc900031df480 R14: 0000000000000070 R15: ffff8880253a41a8
FS: 0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32a23ffc CR3: 000000005f25b000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
rcu_dynticks_curr_cpu_in_eqs kernel/rcu/tree.c:331 [inline]
rcu_is_watching+0x11/0xa0 kernel/rcu/tree.c:1123
rcu_read_lock_held_common kernel/rcu/update.c:108 [inline]
rcu_read_lock_held+0x11/0x40 kernel/rcu/update.c:309
__perf_output_begin kernel/events/ring_buffer.c:170 [inline]
perf_output_begin_forward+0x1af/0xa30 kernel/events/ring_buffer.c:271
__perf_event_output kernel/events/core.c:7814 [inline]
perf_event_output_forward+0x19b/0x2e0 kernel/events/core.c:7832
__perf_event_overflow+0x35f/0x550 kernel/events/core.c:9525
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:ffffc900031dfa80 EFLAGS: 00000206
RAX: 77c0e67949cbb700 RBX: 1ffff9200063bf54 RCX: 77c0e67949cbb700
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a48c0
RBP: ffffc900031dfb50 R08: ffffffff901f10cf R09: 1ffffffff203e219
R10: dffffc0000000000 R11: fffffbfff203e21a R12: ffffffff8c323400
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
__rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
rcu_read_unlock+0x85/0x90 include/linux/rcupdate.h:772
mntput_no_expire+0x306/0x770 fs/namespace.c:1209
mntput fs/namespace.c:1244 [inline]
namespace_unlock+0x3a6/0x440 fs/namespace.c:1463
drop_collected_mounts fs/namespace.c:1948 [inline]
put_mnt_ns+0xdb/0x120 fs/namespace.c:4431
free_nsproxy+0x49/0x3c0 kernel/nsproxy.c:191
do_exit+0x630/0x2110 kernel/exit.c:889
__do_sys_exit kernel/exit.c:973 [inline]
__se_sys_exit kernel/exit.c:971 [inline]
__x64_sys_exit+0x3c/0x40 kernel/exit.c:971
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: 0033:0x7f5ad8ee0159
Code: Unable to access opcode bytes at RIP 0x7f5ad8ee012f.
RSP: 002b:00007f5ad7137fd8 EFLAGS: 00000246 ORIG_RAX: 000000000000003c
RAX: ffffffffffffffda RBX: 00007f5ad9167fa0 RCX: 00007f5ad8ee0159
RDX: 00007f5ad71389c8 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f5ad8f7706b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5ad9168038 R14: 00007f5ad9167fa0 R15: 00007ffe894420a8
task:kworker/u4:5 state:R running task stack:21696 pid: 1271 ppid: 2 flags:0x00004000
Workqueue: netns cleanup_net
Call Trace:
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11c3/0x4350 kernel/sched/core.c:6395
preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6799
irqentry_exit+0x63/0x70 kernel/entry/common.c:435
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__rcu_read_lock+0x2d/0x50 kernel/rcu/tree_plugin.h:400
Code: 8b 1d c7 0c 9d 7e 48 81 c3 3c 04 00 00 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 0f b6 04 08 84 c0 75 11 ff 03 8b 03 <3d> 00 00 00 40 7d 02 5b c3 0f 0b eb fa 89 d9 80 e1 07 80 c1 03 38
RSP: 0018:ffffc90005387a30 EFLAGS: 00000202
RAX: 0000000000000001 RBX: ffff888022575d7c RCX: dffffc0000000000
RDX: ffff888022575940 RSI: ffffffff8a2b3e80 RDI: ffffffff8a7a48c0
RBP: ffffc90005387b30 R08: ffffffff8d8b1eef R09: 1ffffffff1b163dd
R10: dffffc0000000000 R11: fffffbfff1b163de R12: dffffc0000000000
R13: dffffc0000000000 R14: ffffc900019223f8 R15: 0000000000000001
rcu_read_lock include/linux/rcupdate.h:738 [inline]
inet_twsk_purge+0x108/0x820 net/ipv4/inet_timewait_sock.c:268
tcp_sk_exit_batch+0x28/0x90 net/ipv4/tcp_ipv4.c:3241
ops_exit_list net/core/net_namespace.c:177 [inline]
cleanup_net+0x78e/0xba0 net/core/net_namespace.c:635
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
rcu: rcu_preempt kthread starved for 10495 jiffies! g8017 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:27520 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: 4677 Comm: syz.3.120 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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 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:ffffc900030cfac0 EFLAGS: 00000246
RAX: fcaf14722cd32300 RBX: 0000000000000003 RCX: fcaf14722cd32300
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a48c0
RBP: ffffc900030cfb70 R08: ffffffff901f10cf R09: 1ffffffff203e219
R10: dffffc0000000000 R11: fffffbfff203e21a R12: 0000000000000003
R13: dffffc0000000000 R14: dffffc0000000000 R15: 1ffff92000619f58
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
spin_lock include/linux/spinlock.h:364 [inline]
write_seqlock include/linux/seqlock.h:937 [inline]
lock_mount_hash fs/namespace.c:112 [inline]
drop_collected_mounts fs/namespace.c:1945 [inline]
put_mnt_ns+0x7f/0x120 fs/namespace.c:4431
free_nsproxy+0x49/0x3c0 kernel/nsproxy.c:191
do_exit+0x630/0x2110 kernel/exit.c:889
__do_sys_exit kernel/exit.c:973 [inline]
__se_sys_exit kernel/exit.c:971 [inline]
__x64_sys_exit+0x3c/0x40 kernel/exit.c:971
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: 0033:0x7f33f9970159
Code: Unable to access opcode bytes at RIP 0x7f33f997012f.
RSP: 002b:00007f33f7bc7fd8 EFLAGS: 00000246 ORIG_RAX: 000000000000003c
RAX: ffffffffffffffda RBX: 00007f33f9bf7fa0 RCX: 00007f33f9970159
RDX: 00007f33f7bc89c8 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f33f9a0706b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f33f9bf8038 R14: 00007f33f9bf7fa0 R15: 00007ffeeec4c4d8