rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 0-...!: (1 GPs behind) idle=43b/1/0x4000000000000000 softirq=48308/48309 fqs=216
(t=10500 jiffies g=62765 q=233)
rcu: rcu_preempt kthread starved for 10022 jiffies! g62765 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:27464 pid: 15 ppid: 2 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:5030 [inline]
__schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
schedule+0x11b/0x1e0 kernel/sched/core.c:6459
schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145
kthread+0x436/0x520 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 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:722
NMI backtrace for cpu 0
CPU: 0 PID: 1423 Comm: aoe_tx0 Not tainted 5.15.185-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
nmi_cpu_backtrace+0x397/0x3d0 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+0x22f/0x380 kernel/rcu/tree_stall.h:349
print_cpu_stall+0x31d/0x5f0 kernel/rcu/tree_stall.h:633
check_cpu_stall kernel/rcu/tree_stall.h:727 [inline]
rcu_pending kernel/rcu/tree.c:3932 [inline]
rcu_sched_clock_irq+0x6d8/0x1110 kernel/rcu/tree.c:2619
update_process_times+0x193/0x200 kernel/time/timer.c:1818
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:1690 [inline]
__hrtimer_run_queues+0x4fe/0xc40 kernel/time/hrtimer.c:1754
hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1816
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_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xa5/0x100 kernel/locking/spinlock.c:194
Code: 74 05 e8 3e 14 d3 f7 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 06 94 a6 f7 65 8b 05 a7 a3 57 76 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc900054c7900 EFLAGS: 00000206
RAX: 9760d42e0e9c5800 RBX: 0000000000000a02 RCX: 9760d42e0e9c5800
RDX: dffffc0000000000 RSI: ffffffff8a0b11c0 RDI: 0000000000000001
RBP: ffffc900054c7990 R08: dffffc0000000000 R09: fffffbfff1ff3641
R10: fffffbfff1ff3641 R11: 1ffffffff1ff3640 R12: dffffc0000000000
R13: ffff8880787b7600 R14: ffffffff963c9408 R15: 1ffff92000a98f20
spin_unlock_irqrestore include/linux/spinlock.h:418 [inline]
uart_write+0x430/0x880 drivers/tty/serial/serial_core.c:574
handle_tx+0x23f/0x600 drivers/net/caif/caif_serial.c:236
__netdev_start_xmit include/linux/netdevice.h:5027 [inline]
netdev_start_xmit include/linux/netdevice.h:5041 [inline]
xmit_one net/core/dev.c:3649 [inline]
dev_hard_start_xmit+0x2a5/0x7e0 net/core/dev.c:3665
__dev_queue_xmit+0x19df/0x2ed0 net/core/dev.c:4288
tx+0x65/0x160 drivers/block/aoe/aoenet.c:63
kthread+0x1bc/0x390 drivers/block/aoe/aoecmd.c:1238
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
watchdog: BUG: soft lockup - CPU#0 stuck for 225s! [aoe_tx0:1423]
Modules linked in:
irq event stamp: 625498195
hardirqs last enabled at (625498194): [] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
hardirqs last enabled at (625498194): [] _raw_spin_unlock_irqrestore+0x82/0x100 kernel/locking/spinlock.c:194
hardirqs last disabled at (625498195): [] sysvec_apic_timer_interrupt+0xa/0xc0 arch/x86/kernel/apic/apic.c:1108
softirqs last enabled at (33606): [] local_bh_enable+0x5/0x20 include/linux/bottom_half.h:31
softirqs last disabled at (33610): [] local_bh_disable+0x5/0x20 include/linux/bottom_half.h:18
CPU: 0 PID: 1423 Comm: aoe_tx0 Not tainted 5.15.185-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x32/0x60 kernel/kcov.c:206
Code: 94 ad 8a 7e 65 8b 15 95 ad 8a 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 34 16 00 00 00 74 2c 8b 91 10 16 00 00 <83> fa 02 75 21 48 8b 91 18 16 00 00 48 8b 32 48 8d 7e 01 8b 89 14
RSP: 0018:ffffc900054c7a38 EFLAGS: 00000246
RAX: ffffffff853c9984 RBX: 0000000000000fff RCX: ffff888022a23b80
RDX: 0000000000000000 RSI: 0000000000000fff RDI: 0000000000000000
RBP: 0000000000000020 R08: dffffc0000000000 R09: ffffed1003f0b1f1
R10: ffffed1003f0b1f1 R11: 1ffff11003f0b1f0 R12: 0000000000000020
R13: dffffc0000000000 R14: ffff888060c4f8c0 R15: ffff8880787b7000
FS: 0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32218ff8 CR3: 000000007e5fc000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
handle_tx+0x1d4/0x600 drivers/net/caif/caif_serial.c:236
__netdev_start_xmit include/linux/netdevice.h:5027 [inline]
netdev_start_xmit include/linux/netdevice.h:5041 [inline]
xmit_one net/core/dev.c:3649 [inline]
dev_hard_start_xmit+0x2a5/0x7e0 net/core/dev.c:3665
__dev_queue_xmit+0x19df/0x2ed0 net/core/dev.c:4288
tx+0x65/0x160 drivers/block/aoe/aoenet.c:63
kthread+0x1bc/0x390 drivers/block/aoe/aoecmd.c:1238
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:722