rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-...!: (1 GPs behind) idle=b5bc/1/0x4000000000000000 softirq=40987/40989 fqs=122 rcu: (t=10502 jiffies g=42245 q=509 ncpus=2) rcu: rcu_preempt kthread starved for 10259 jiffies! g42245 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:26728 pid:17 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5381 [inline] __schedule+0x1553/0x45a0 kernel/sched/core.c:6700 schedule+0xbd/0x170 kernel/sched/core.c:6774 schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168 rcu_gp_fqs_loop+0x313/0x1590 kernel/rcu/tree.c:1667 rcu_gp_kthread+0x9d/0x3b0 kernel/rcu/tree.c:1866 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:pv_native_safe_halt+0xf/0x10 arch/x86/kernel/paravirt.c:148 Code: 18 23 02 c3 cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d 43 32 44 00 fb f4 66 0f 1f 00 55 41 57 41 56 41 54 53 50 8b 2f eb 2e 41 89 de 80 RSP: 0018:ffffc90000187de0 EFLAGS: 000002c2 RAX: a41b21dfbbed8000 RBX: ffffffff8162a570 RCX: a41b21dfbbed8000 RDX: 0000000000000001 RSI: ffffffff8acac900 RDI: ffffffff8b1c80e0 RBP: ffffc90000187f20 R08: ffff8880b8f36b2b R09: 1ffff110171e6d65 R10: dffffc0000000000 R11: ffffed10171e6d66 R12: 1ffff110036ce780 R13: 1ffff92000030fc8 R14: 0000000000000001 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055558f3dc4e8 CR3: 0000000025930000 CR4: 00000000003506e0 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:753 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97 cpuidle_idle_call kernel/sched/idle.c:170 [inline] do_idle+0x1f0/0x4e0 kernel/sched/idle.c:282 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:380 start_secondary+0xee/0xf0 arch/x86/kernel/smpboot.c:323 secondary_startup_64_no_verify+0x179/0x17b CPU: 0 PID: 1287 Comm: aoe_tx0 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0xc0/0x120 kernel/locking/spinlock.c:194 Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 bb ca ce f6 65 8b 05 ac 00 76 75 85 c0 74 3c 48 c7 04 24 0e 36 RSP: 0018:ffffc90004eff8c0 EFLAGS: 00000206 RAX: dffffc0000000004 RBX: 0000000000000a06 RCX: 47dcad66a18c1800 RDX: dffffc0000000000 RSI: ffffffff8acac900 RDI: 0000000000000001 RBP: ffffc90004eff958 R08: ffffffff911be627 R09: 1ffffffff2237cc4 R10: dffffc0000000000 R11: fffffbfff2237cc5 R12: dffffc0000000000 R13: dffffc0000000000 R14: ffffffff975eed00 R15: 1ffff920009dff18 FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f88c15f6d58 CR3: 000000002d2f2000 CR4: 00000000003506f0 Call Trace: spin_unlock_irqrestore include/linux/spinlock.h:406 [inline] uart_write_room+0x130/0x2c0 drivers/tty/serial/serial_core.c:647 handle_tx+0x15e/0x610 drivers/net/caif/caif_serial.c:226 __netdev_start_xmit include/linux/netdevice.h:4943 [inline] netdev_start_xmit include/linux/netdevice.h:4957 [inline] xmit_one net/core/dev.c:3645 [inline] dev_hard_start_xmit+0x246/0x740 net/core/dev.c:3661 __dev_queue_xmit+0x1ac2/0x36b0 net/core/dev.c:4451 dev_queue_xmit include/linux/netdevice.h:3113 [inline] tx+0x6b/0x180 drivers/block/aoe/aoenet.c:63 kthread+0x1d2/0x3b0 drivers/block/aoe/aoecmd.c:1241 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293