rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 1-...!: (1 GPs behind) idle=a81/1/0x4000000000000000 softirq=9346/9347 fqs=0
(t=10501 jiffies g=10133 q=9)
rcu: rcu_preempt kthread starved for 10502 jiffies! g10133 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:28080 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:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 5530 Comm: syz.1.302 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
RIP: 0010:__lock_acquire+0xe30/0x7d40 kernel/locking/lockdep.c:5090
Code: 48 89 cb 48 8d 3c c5 c0 60 04 91 be 08 00 00 00 e8 35 68 61 00 49 b8 00 00 00 00 00 fc ff df 48 63 c3 48 0f a3 05 f0 5e a7 0f <0f> 83 54 0a 00 00 4d 89 fc 49 8d 9d e0 0a 00 00 48 89 d8 48 c1 e8
RSP: 0018:ffffc900000078e0 EFLAGS: 00000057
RAX: 0000000000000015 RBX: 0000000000000015 RCX: ffffffff815d01bb
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff910460c0
RBP: ffffc90000007b28 R08: dffffc0000000000 R09: 1ffffffff2208c18
R10: dffffc0000000000 R11: fffffbfff2208c19 R12: ffff88802836e414
R13: ffff88802836d940 R14: ffff88802836e458 R15: ffff88802836e478
FS: 00007f86d07426c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000058 CR3: 000000005c941000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
lock_acquire+0x19f/0x400 kernel/locking/lockdep.c:5737
rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
rcu_read_lock include/linux/rcupdate.h:740 [inline]
send_sigqueue+0xd1/0x620 kernel/signal.c:1986
posix_timer_event kernel/time/posix-timers.c:360 [inline]
posix_timer_fn+0x149/0x350 kernel/time/posix-timers.c:386
__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x4ea/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:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202
Code: 00 00 00 66 90 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 de 2e 8b f7 48 89 df e8 e6 10 8c f7 e8 21 0d ad f7 fb bf 01 00 00 00 26 17 80 f7 65 8b 05 a7 2d 30 76 85 c0 74 02 5b c3 e8 e4 3a 2e
RSP: 0018:ffffc90002f0fbc0 EFLAGS: 00000282
RAX: 1e0208d6d74a0100 RBX: ffff88805f132e40 RCX: 1e0208d6d74a0100
RDX: dffffc0000000000 RSI: ffffffff8a2b2b60 RDI: 0000000000000001
RBP: 0000000000000000 R08: ffff88805f132e43 R09: 1ffff1100be265c8
R10: dffffc0000000000 R11: ffffed100be265c9 R12: dffffc0000000000
R13: ffff88805f132e40 R14: 0000000000000021 R15: 000000001c000004
spin_unlock_irq include/linux/spinlock.h:414 [inline]
get_signal+0x11f2/0x12e0 kernel/signal.c:2916
arch_do_signal_or_restart+0xe6/0x12a0 arch/x86/kernel/signal.c:867
handle_signal_work kernel/entry/common.c:157 [inline]
exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:181
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:217
__syscall_exit_to_user_mode_work kernel/entry/common.c:299 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:310
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f86d24eb559
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:00007f86d07420e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f86d2771fa8 RCX: 00007f86d24eb559
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f86d2771fa8
RBP: 00007f86d2771fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f86d2772038 R14: 00007ffda5c7e1a0 R15: 00007ffda5c7e288
NMI backtrace for cpu 1
CPU: 1 PID: 5524 Comm: syz.2.303 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
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_dump_cpu_stacks+0x22d/0x380 kernel/rcu/tree_stall.h:349
print_cpu_stall+0x31f/0x5f0 kernel/rcu/tree_stall.h:633
check_cpu_stall kernel/rcu/tree_stall.h:727 [inline]
rcu_pending kernel/rcu/tree.c:3936 [inline]
rcu_sched_clock_irq+0x6ec/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:lock_acquire+0x209/0x400 kernel/locking/lockdep.c:5741
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3c 04 f8 0f 85 f0 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 43 c7 44 3c 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc9000323fb00 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 8ce21e63b4769a00
RDX: 0000000000000000 RSI: ffffffff8a2b3e00 RDI: ffffffff8a7a4bc0
RBP: ffffc9000323fc20 R08: dffffc0000000000 R09: 1ffffffff2208c1e
R10: dffffc0000000000 R11: fffffbfff2208c1f R12: 1ffff92000647f6c
R13: ffff888074400128 R14: 0000000000000246 R15: dffffc0000000000
__might_fault+0xb3/0x110 mm/memory.c:5357
_copy_to_user+0x29/0x130 lib/usercopy.c:35
copy_to_user include/linux/uaccess.h:200 [inline]
copy_siginfo_to_user+0x20/0x80 kernel/signal.c:3380
__setup_rt_frame arch/x86/kernel/signal.c:490 [inline]
setup_rt_frame arch/x86/kernel/signal.c:780 [inline]
handle_signal arch/x86/kernel/signal.c:824 [inline]
arch_do_signal_or_restart+0xcf9/0x12a0 arch/x86/kernel/signal.c:869
handle_signal_work kernel/entry/common.c:157 [inline]
exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:181
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:217
__syscall_exit_to_user_mode_work kernel/entry/common.c:299 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:310
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fbb32ced557
Code: 83 c8 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
RSP: 002b:00007fbb30f440e8 EFLAGS: 00000246
RAX: 00000000000000ca RBX: 00007fbb32f73fa8 RCX: 00007fbb32ced559
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fbb32f73fa8
RBP: 00007fbb32f73fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbb32f74038 R14: 00007ffd95ed7410 R15: 00007ffd95ed74f8