rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 0-...!: (10499 ticks this GP) idle=c1dc/1/0x4000000000000000 softirq=50678/50679 fqs=451
rcu: (t=10500 jiffies g=47465 q=870 ncpus=2)
rcu: rcu_preempt kthread starved for 9451 jiffies! g47465 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:27648 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5295 [inline]
__schedule+0x1585/0x5340 kernel/sched/core.c:6907
__schedule_loop kernel/sched/core.c:6989 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7004
schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095
rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297
kthread+0x388/0x470 kernel/kthread.c:467
ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:246 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x10/0x90 kernel/kcov.c:314
Code: cc cc 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 65 48 8b 15 68 08 57 11 <65> 8b 0d 89 08 57 11 81 e1 00 01 ff 00 74 11 81 f9 00 01 00 00 75
RSP: 0018:ffffc90000a08d78 EFLAGS: 00000002
RAX: ffffffff81b27b5d RBX: 0000000000000004 RCX: 0000000000000100
RDX: ffff88801e2b8000 RSI: 0000000000000004 RDI: 0000000000000009
RBP: ffffc90000a08ec8 R08: ffffffff81b34517 R09: ffffffff9a2c5508
R10: dffffc0000000000 R11: ffffffff816b3750 R12: 0000000000000004
R13: dffffc0000000000 R14: 1ffff920001411c8 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888125555000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f49c723621e CR3: 0000000029fc0000 CR4: 00000000003526f0
Call Trace:
__next_base kernel/time/hrtimer.c:506 [inline]
__hrtimer_run_queues+0x15d/0xcc0 kernel/time/hrtimer.c:1823
hrtimer_run_softirq+0x182/0x5a0 kernel/time/hrtimer.c:1866
handle_softirqs+0x22a/0x870 kernel/softirq.c:626
__do_softirq kernel/softirq.c:660 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0x5f/0x150 kernel/softirq.c:727
irq_exit_rcu+0x9/0x30 kernel/softirq.c:743
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63
Code: 6e 6b 02 c3 cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 23 8d 19 00 fb f4 7c ea 02 00 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90
RSP: 0018:ffffc90000197e20 EFLAGS: 00000242
RAX: 000000000120499d RBX: ffffffff819a933d RCX: 0000000080000001
RDX: 0000000000000001 RSI: ffffffff8defaa6c RDI: ffffffff8c27f680
RBP: ffffc90000197f10 R08: ffff8880b873395b R09: 1ffff110170e672b
R10: dffffc0000000000 R11: ffffed10170e672c R12: ffffffff9011c5b0
R13: 1ffff11003c57000 R14: 0000000000000001 R15: 0000000000000001
arch_safe_halt arch/x86/kernel/process.c:766 [inline]
default_idle+0x9/0x20 arch/x86/kernel/process.c:767
default_idle_call+0x72/0xb0 kernel/sched/idle.c:122
cpuidle_idle_call kernel/sched/idle.c:191 [inline]
do_idle+0x1bd/0x500 kernel/sched/idle.c:332
cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:430
start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:312
common_startup_64+0x13e/0x147
CPU: 0 UID: 0 PID: 1308 Comm: aoe_tx0 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x47/0x80 kernel/locking/spinlock.c:194
Code: f7 e8 ed c2 ef f5 f7 c3 00 02 00 00 74 05 e8 d0 17 1b f6 9c 58 a9 00 02 00 00 75 27 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 34 89 e1 f5 65 8b 05 9d 3f 6a 07 85 c0 74 18 5b 41 5e e9 81 48
RSP: 0018:ffffc9000539f808 EFLAGS: 00000206
RAX: 0000000000000002 RBX: 0000000000000286 RCX: 0000000000000202
RDX: 0000000000000002 RSI: ffffffff8defaa6c RDI: 0000000000000001
RBP: dffffc0000000000 R08: ffffffff9011c5b7 R09: 1ffffffff20238b6
R10: dffffc0000000000 R11: fffffbfff20238b7 R12: 0000000000000000
R13: 0000000000000000 R14: ffffffff9a5da400 R15: ffffffff8f00e1a0
FS: 0000000000000000(0000) GS:ffff888125455000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f49c3802000 CR3: 0000000037c32000 CR4: 00000000003526f0
Call Trace:
spin_unlock_irqrestore include/linux/spinlock.h:407 [inline]
uart_port_unlock_irqrestore include/linux/serial_core.h:788 [inline]
uart_port_unlock_deref drivers/tty/serial/serial_core.c:91 [inline]
uart_write_room+0x3b0/0x840 drivers/tty/serial/serial_core.c:647
handle_tx+0x163/0x610 drivers/net/caif/caif_serial.c:212
__netdev_start_xmit include/linux/netdevice.h:5290 [inline]
netdev_start_xmit include/linux/netdevice.h:5299 [inline]
xmit_one net/core/dev.c:3872 [inline]
dev_hard_start_xmit+0x2d8/0x870 net/core/dev.c:3888
__dev_queue_xmit+0x168f/0x38a0 net/core/dev.c:4837
dev_queue_xmit include/linux/netdevice.h:3390 [inline]
tx+0x6b/0x190 drivers/block/aoe/aoenet.c:62
kthread+0x1e0/0x3f0 drivers/block/aoe/aoecmd.c:1241
kthread+0x388/0x470 kernel/kthread.c:467
ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245