rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: (detected by 1, t=10502 jiffies, g=13801, q=206 ncpus=2) rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294964877-4294954375), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10502 jiffies! g13801 f0x2 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:27736 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5258 [inline] __schedule+0x150e/0x5070 kernel/sched/core.c:6866 __schedule_loop kernel/sched/core.c:6948 [inline] schedule+0x165/0x360 kernel/sched/core.c:6963 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 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: 6083 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline] RIP: 0010:rcu_is_watching+0x15/0xb0 kernel/rcu/tree.c:751 Code: 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 41 57 41 56 53 65 ff 05 90 68 1c 11 e8 7b 86 bf 09 <89> c3 83 f8 08 73 65 49 bf 00 00 00 00 00 fc ff df 4c 8d 34 dd d0 RSP: 0018:ffffc90000007c60 EFLAGS: 00000082 RAX: 0000000000000000 RBX: 0000000000000001 RCX: f20b6173f261ea00 RDX: ffff88802cab3d00 RSI: ffffffff8be247c0 RDI: ffffffff8be24780 RBP: 0000000000000001 R08: ffff88802f7a5343 R09: 1ffff11005ef4a68 R10: dffffc0000000000 R11: ffffed1005ef4a69 R12: dffffc0000000000 R13: ffff88803329a800 R14: ffff88802cab4668 R15: ffffffff8187ebc3 FS: 0000555558b30500(0000) GS:ffff8881259dc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000000140 CR3: 0000000073ee0000 CR4: 00000000003526f0 Call Trace: rcu_read_unlock include/linux/rcupdate.h:895 [inline] class_rcu_destructor include/linux/rcupdate.h:1195 [inline] posixtimer_send_sigqueue+0x4a4/0xa70 kernel/signal.c:2085 posix_timer_queue_signal kernel/time/posix-timers.c:364 [inline] posix_timer_fn+0x121/0x1c0 kernel/time/posix-timers.c:379 __run_hrtimer kernel/time/hrtimer.c:1777 [inline] __hrtimer_run_queues+0x51c/0xc30 kernel/time/hrtimer.c:1841 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1903 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline] __sysvec_apic_timer_interrupt+0x102/0x3e0 arch/x86/kernel/apic/apic.c:1062 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1056 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline] RIP: 0010:_raw_spin_unlock_irq+0x29/0x50 kernel/locking/spinlock.c:202 Code: 90 f3 0f 1e fa 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 1a fe 34 f6 48 89 df e8 52 75 35 f6 e8 4d f3 5f f6 fb bf 01 00 00 00 82 6a 27 f6 65 8b 05 db 5f 5a 07 85 c0 74 07 5b e9 c1 4b 00 00 RSP: 0018:ffffc90003787c60 EFLAGS: 00000286 RAX: f20b6173f261ea00 RBX: ffff88802f7a5340 RCX: f20b6173f261ea00 RDX: 0000000000000000 RSI: ffffffff8daa9dc3 RDI: 0000000000000001 RBP: 0000000000000011 R08: ffffffff8fc3d077 R09: 1ffffffff1f87a0e R10: dffffc0000000000 R11: fffffbfff1f87a0f R12: 1ffff11005ef4abb R13: 0000000000000000 R14: 0000000004000000 R15: ffff88802f7a55d8 spin_unlock_irq include/linux/spinlock.h:401 [inline] get_signal+0x11a7/0x1340 kernel/signal.c:3037 arch_do_signal_or_restart+0x9a/0x7a0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline] exit_to_user_mode_loop+0x87/0x4f0 kernel/entry/common.c:75 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x2d0/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f78c698f749 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffe246999c8 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 00007f78c6be5fa0 RCX: 00007f78c698f749 RDX: 0000200000000240 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007f78c6a13f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f78c6be5fa0 R14: 00007f78c6be5fa0 R15: 0000000000000004