rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-...!: (1 GPs behind) idle=fbbc/1/0x4000000000000000 softirq=71264/71265 fqs=239 rcu: (t=10500 jiffies g=58017 q=371 ncpus=2) rcu: rcu_preempt kthread starved for 10009 jiffies! g58017 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:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5325 [inline] __schedule+0x1190/0x5de0 kernel/sched/core.c:6929 __schedule_loop kernel/sched/core.c:7011 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:7026 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1ea/0xaf0 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x26d/0x380 kernel/rcu/tree.c:2285 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x675/0x7d0 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 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x70 kernel/kcov.c:210 Code: b6 6b 57 00 48 89 df 5b e9 1d 1a 5d 00 be 03 00 00 00 5b e9 e2 a5 e7 02 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1e fa 48 8b 34 24 65 48 8b 15 78 54 e4 11 65 8b 05 89 54 e4 RSP: 0018:ffffc90000007ba8 EFLAGS: 00000046 RAX: 0000000000000000 RBX: 0000000000000083 RCX: ffffffff875b3655 RDX: ffffffff8e097a00 RSI: 0000000000000003 RDI: 0000000000000005 RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000003 R10: 0000000000000003 R11: ffff888144bf7470 R12: ffff888144b68000 R13: 0000000000000003 R14: 0000000000000000 R15: ffff888144b686c8 FS: 0000000000000000(0000) GS:ffff888124a0a000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f9bf62ef7d9 CR3: 0000000078fe9000 CR4: 00000000003526f0 Call Trace: find_endpoint+0x103/0x2c0 drivers/usb/gadget/udc/dummy_hcd.c:1583 dummy_timer+0x4dd/0x3a00 drivers/usb/gadget/udc/dummy_hcd.c:1864 __run_hrtimer kernel/time/hrtimer.c:1777 [inline] __hrtimer_run_queues+0x202/0xad0 kernel/time/hrtimer.c:1841 hrtimer_run_softirq+0x17d/0x350 kernel/time/hrtimer.c:1858 handle_softirqs+0x219/0x8e0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0x109/0x170 kernel/softirq.c:723 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline] sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1052 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:82 Code: 07 6d 02 c3 cc cc cc cc 0f 1f 00 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 43 d5 29 00 fb f4 3c 0a 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 RSP: 0018:ffffffff8e007df8 EFLAGS: 000002c6 RAX: 0000000002d4d6f5 RBX: 0000000000000000 RCX: ffffffff8b6052a9 RDX: 0000000000000000 RSI: ffffffff8da2a259 RDI: ffffffff8bf06e40 RBP: fffffbfff1c12f40 R08: 0000000000000001 R09: ffffed1017086655 R10: ffff8880b84332ab R11: 0000000000000001 R12: 0000000000000000 R13: ffffffff8e097a00 R14: ffffffff9081f6d0 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:767 default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:190 [inline] do_idle+0x38d/0x500 kernel/sched/idle.c:330 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:428 rest_init+0x16b/0x2b0 init/main.c:757 start_kernel+0x3f6/0x4e0 init/main.c:1111 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x148 CPU: 1 UID: 0 PID: 1300 Comm: aoe_tx0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 RIP: 0010:uart_write_room+0x0/0x940 drivers/tty/serial/serial_core.c:639 Code: fc e9 7a fe ff ff e8 ff e0 fe fc e9 a9 fe ff ff 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1e fa 41 57 41 56 41 55 41 54 55 53 48 89 fb 48 83 ec 10 e8 RSP: 0018:ffffc9000429f9b0 EFLAGS: 00000293 RAX: 0000000000000000 RBX: ffff88802556f000 RCX: ffffffff8669974f RDX: ffff88802871c900 RSI: ffffffff851fd02d RDI: ffff88802556f000 RBP: 0000000000000800 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000020 R11: 0000000000000001 R12: ffffffff8526b700 R13: ffff88801b7f4d80 R14: 0000000000000020 R15: ffff88801b7f4000 FS: 0000000000000000(0000) GS:ffff888124b0a000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000404030 CR3: 0000000059bb5000 CR4: 00000000003526f0 Call Trace: tty_write_room+0x66/0x90 drivers/tty/tty_ioctl.c:69 handle_tx+0x14f/0x630 drivers/net/caif/caif_serial.c:212 __netdev_start_xmit include/linux/netdevice.h:5248 [inline] netdev_start_xmit include/linux/netdevice.h:5257 [inline] xmit_one net/core/dev.c:3845 [inline] dev_hard_start_xmit+0x97/0x740 net/core/dev.c:3861 __dev_queue_xmit+0xa46/0x4490 net/core/dev.c:4763 dev_queue_xmit include/linux/netdevice.h:3365 [inline] tx+0xcc/0x190 drivers/block/aoe/aoenet.c:62 kthread+0x1e4/0x3e0 drivers/block/aoe/aoecmd.c:1241 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 vkms_vblank_simulate: vblank timer overrun