rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5847/2:b..l P5800/5:b..l rcu: (detected by 0, t=10502 jiffies, g=11433, q=5327 ncpus=2) task:syz-executor state:R running task stack:21592 pid:5800 tgid:5800 ppid:1 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x145f/0x5070 kernel/sched/core.c:6863 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7190 irqentry_exit+0x5e3/0x670 kernel/entry/common.c:216 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_acquire+0x222/0x340 kernel/locking/lockdep.c:5872 Code: ff ff ff e8 d0 40 35 09 f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 aa 9f 16 10 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 4f ff 38 09 cc 48 8d 3d a7 c9 41 RSP: 0018:ffffc90004c3f388 EFLAGS: 00000286 RAX: 355844eb3b2b8300 RBX: 0000000000000000 RCX: 0000000000000046 RDX: 000000009d9c53a4 RSI: ffffffff8cfdf9e2 RDI: ffffffff8b3f5a60 RBP: ffffffff8228c738 R08: ffffffff8228c738 R09: ffffffff8d5ae940 R10: dffffc0000000000 R11: fffff940002a9351 R12: 0000000000000002 R13: ffffffff8d5ae940 R14: 0000000000000000 R15: 0000000000000246 rcu_lock_acquire include/linux/rcupdate.h:331 [inline] rcu_read_lock include/linux/rcupdate.h:867 [inline] page_table_check_set+0x165/0x610 mm/page_table_check.c:112 page_table_check_ptes_set include/linux/page_table_check.h:76 [inline] set_ptes include/linux/pgtable.h:292 [inline] __copy_present_ptes mm/memory.c:1102 [inline] copy_present_ptes mm/memory.c:1181 [inline] copy_pte_range mm/memory.c:1304 [inline] copy_pmd_range+0x49e2/0x7980 mm/memory.c:1392 copy_pud_range mm/memory.c:1429 [inline] copy_p4d_range mm/memory.c:1453 [inline] copy_page_range+0xae6/0x1130 mm/memory.c:1535 dup_mmap+0xf56/0x1b40 mm/mmap.c:1827 dup_mm kernel/fork.c:1529 [inline] copy_mm+0x13c/0x4b0 kernel/fork.c:1581 copy_process+0x1665/0x3960 kernel/fork.c:2221 kernel_clone+0x21d/0x7a0 kernel/fork.c:2651 __do_sys_clone kernel/fork.c:2792 [inline] __se_sys_clone kernel/fork.c:2776 [inline] __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2776 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f3caacc5e93 RSP: 002b:00007fff69de85c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f3caacc5e93 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001 R10: 000055556681e7d0 R11: 0000000000000246 R12: 0000000000000000 R13: 00000000000927c0 R14: 0000000000022554 R15: 00007fff69de8760 task:kworker/0:4 state:R running task stack:20880 pid:5847 tgid:5847 ppid:2 task_flags:0x4208060 flags:0x00080000 Workqueue: wg-crypt-wg1 wg_packet_decrypt_worker Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x145f/0x5070 kernel/sched/core.c:6863 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:7047 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 rt_mutex_wake_up_q kernel/locking/rtmutex.c:575 [inline] rt_mutex_slowunlock+0x668/0x8a0 kernel/locking/rtmutex.c:1469 spin_unlock include/linux/spinlock_rt.h:105 [inline] kcov_remote_start+0x186/0x710 kernel/kcov.c:890 kcov_remote_start_usb include/linux/kcov.h:55 [inline] kcov_remote_start_usb_softirq include/linux/kcov.h:68 [inline] __usb_hcd_giveback_urb+0x38a/0x5e0 drivers/usb/core/hcd.c:1660 usb_giveback_urb_bh+0x296/0x420 drivers/usb/core/hcd.c:1695 process_one_work kernel/workqueue.c:3257 [inline] process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340 bh_worker+0x2ca/0x630 kernel/workqueue.c:3611 tasklet_hi_action+0xf/0x70 kernel/softirq.c:958 handle_softirqs+0x1df/0x650 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] __local_bh_enable_ip+0x171/0x2c0 kernel/softirq.c:302 local_bh_enable include/linux/bottom_half.h:33 [inline] spin_unlock_bh include/linux/spinlock_rt.h:111 [inline] ptr_ring_consume_bh include/linux/ptr_ring.h:377 [inline] wg_packet_decrypt_worker+0x2d7/0xce0 drivers/net/wireguard/receive.c:499 process_one_work kernel/workqueue.c:3257 [inline] process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 rcu: rcu_preempt kthread timer wakeup didn't happen for 2973 jiffies! g11433 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=1 timer-softirq=10973 rcu: rcu_preempt kthread starved for 2974 jiffies! g11433 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27808 pid:18 tgid:18 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x145f/0x5070 kernel/sched/core.c:6863 __schedule_loop kernel/sched/core.c:6945 [inline] schedule+0x165/0x360 kernel/sched/core.c:6960 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+0x510/0xa50 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 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:82 Code: 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 97 16 00 f3 0f 1e fa fb f4 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffc900001d7e20 EFLAGS: 000002c2 RAX: 00000000001472b9 RBX: ffffffff8195d83e RCX: 0000000080000001 RDX: 0000000000000001 RSI: ffffffff8ce0c91b RDI: ffffffff8b3f5a60 RBP: ffffc900001d7f10 R08: ffff8880b8933c5b R09: 1ffff1101712678b R10: dffffc0000000000 R11: ffffed101712678c R12: ffffffff8edb3670 R13: 1ffff11003758b58 R14: 0000000000000001 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff888126dee000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f29386eff05 CR3: 0000000039eaa000 CR4: 00000000003526f0 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:767 default_idle_call+0x73/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:191 [inline] do_idle+0x1be/0x4d0 kernel/sched/idle.c:332 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:430 start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:312 common_startup_64+0x13e/0x147