rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5645/1:b..l P8948/2:b..l rcu: (detected by 0, t=10502 jiffies, g=47781, q=336 ncpus=2) task:syz.0.844 state:R running task stack:25064 pid:8948 tgid:8943 ppid:5643 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5388 [inline] __schedule+0x1821/0x5740 kernel/sched/core.c:7189 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7513 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline] irqentry_exit+0x14f/0x760 kernel/entry/common.c:164 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:unwind_next_frame+0x49f/0x2550 arch/x86/kernel/unwind_orc.c:-1 Code: 4c 8d 6a 05 4c 89 e0 48 c1 e8 03 0f b6 04 28 84 c0 0f 85 c2 19 00 00 4c 89 e8 48 c1 e8 03 0f b6 04 28 84 c0 0f 85 d5 19 00 00 <41> 0f b6 44 24 01 83 e0 07 0f 84 75 16 00 00 83 f8 01 4c 8b 7c 24 RSP: 0018:ffffc90004ec7018 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffffffff90a27ce8 RCX: ffffffff90a27cec RDX: ffffffff914ae69e RSI: ffffffff914ae69e RDI: ffffffff8c28af00 RBP: dffffc0000000000 R08: 0000000000000001 R09: ffffffff8e95cd60 R10: ffffc90004ec7138 R11: ffffffff81b0ebd0 R12: ffffffff914ae6a2 R13: ffffffff914ae6a3 R14: ffffc90004ec70e8 R15: ffffffff90a27ce8 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 ref_tracker_alloc+0x1af/0x4c0 lib/ref_tracker.c:276 __netdev_tracker_alloc include/linux/netdevice.h:4471 [inline] netdev_hold include/linux/netdevice.h:4500 [inline] dst_init+0xd9/0x480 net/core/dst.c:52 dst_alloc+0x12a/0x170 net/core/dst.c:94 rt_dst_alloc net/ipv4/route.c:1651 [inline] __mkroute_output net/ipv4/route.c:2655 [inline] ip_route_output_key_hash_rcu+0x14d0/0x25d0 net/ipv4/route.c:2875 ip_route_output_key_hash+0x18d/0x2a0 net/ipv4/route.c:2705 __ip_route_output_key include/net/route.h:169 [inline] ip_route_output_flow+0x2a/0x150 net/ipv4/route.c:2932 udp_sendmsg+0x141a/0x21a0 net/ipv4/udp.c:1409 sock_sendmsg_nosec net/socket.c:787 [inline] __sock_sendmsg net/socket.c:802 [inline] ____sys_sendmsg+0x80a/0x9f0 net/socket.c:2698 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2752 __sys_sendmmsg+0x27c/0x4e0 net/socket.c:2841 __do_sys_sendmmsg net/socket.c:2868 [inline] __se_sys_sendmmsg net/socket.c:2865 [inline] __x64_sys_sendmmsg+0xa0/0xc0 net/socket.c:2865 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f548859cdd9 RSP: 002b:00007f5489416028 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007f5488816180 RCX: 00007f548859cdd9 RDX: 0000000000000300 RSI: 0000200000004d00 RDI: 0000000000000008 RBP: 00007f5488632d69 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000f00 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f5488816218 R14: 00007f5488816180 R15: 00007f548893fa48 task:syz-executor state:R running task stack:21512 pid:5645 tgid:5645 ppid:5621 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5388 [inline] __schedule+0x1821/0x5740 kernel/sched/core.c:7189 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:7370 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:169 [inline] _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:190 spin_unlock include/linux/spinlock.h:390 [inline] copy_pte_range mm/memory.c:1331 [inline] copy_pmd_range+0x4f04/0x5970 mm/memory.c:1392 copy_pud_range mm/memory.c:1429 [inline] copy_p4d_range mm/memory.c:1453 [inline] copy_page_range+0xbe8/0x11f0 mm/memory.c:1539 dup_mmap+0xf40/0x1d90 mm/mmap.c:1840 dup_mm kernel/fork.c:1534 [inline] copy_mm+0x13b/0x4a0 kernel/fork.c:1586 copy_process+0x1f1c/0x4440 kernel/fork.c:2264 kernel_clone+0x284/0x8f0 kernel/fork.c:2721 __do_sys_clone kernel/fork.c:2862 [inline] __se_sys_clone kernel/fork.c:2846 [inline] __x64_sys_clone+0x1b6/0x230 kernel/fork.c:2846 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fe443bc5852 RSP: 002b:00007fe443f3fc60 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007fe443f3fc60 RCX: 00007fe443bc5852 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 00007fe443f3fdec R08: 0000000000000000 R09: 0000000000000001 R10: 00005555906ab7d0 R11: 0000000000000246 R12: 0000000000000001 R13: 00000000000927c0 R14: 000000000003eac9 R15: 00007fe443f3fe40 rcu: rcu_preempt kthread starved for 3810 jiffies! g47781 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:27544 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5388 [inline] __schedule+0x1821/0x5740 kernel/sched/core.c:7189 __schedule_loop kernel/sched/core.c:7268 [inline] schedule+0x164/0x360 kernel/sched/core.c:7283 schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 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: CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63 Code: 9b 7d 02 e9 93 f7 02 00 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 53 a1 20 00 fb f4 cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 RSP: 0018:ffffffff8e607dc0 EFLAGS: 00000246 RAX: 00000000004ef205 RBX: ffffffff819a93ba RCX: 0000000080000001 RDX: 0000000000000001 RSI: ffffffff8dfa6837 RDI: ffffffff8c28af60 RBP: ffffffff8e607eb0 R08: ffff8880b86339db R09: 1ffff110170c673b R10: dffffc0000000000 R11: ffffed10170c673c R12: 0000000000000000 R13: 1ffffffff1cd25d8 R14: 0000000000000000 R15: 1ffffffff1cd25d8 FS: 0000000000000000(0000) GS:ffff88812528d000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f1f1fe84e05 CR3: 0000000079af6000 CR4: 00000000003526f0 DR0: 0000000000000004 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: arch_safe_halt arch/x86/kernel/process.c:766 [inline] default_idle+0x9/0x20 arch/x86/kernel/process.c:767 default_idle_call+0x72/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:199 [inline] do_idle+0x36a/0x5f0 kernel/sched/idle.c:352 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:451 rest_init+0x2de/0x300 init/main.c:762 start_kernel+0x38a/0x3e0 init/main.c:1220 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x147 usb 3-1: pegasus_irq - nonzero urb status received: -71 usb 3-1: pegasus_irq - nonzero urb status received: -71 usb 3-1: pegasus_irq - nonzero urb status received: -71 usb 3-1: pegasus_irq - nonzero urb status received: -71 usb 3-1: pegasus_irq - nonzero urb status received: -71 usb 3-1: pegasus_irq - nonzero urb status received: -71 usb 3-1: pegasus_irq - nonzero urb status received: -71 usb 3-1: pegasus_irq - nonzero urb status received: -71 usb 3-1: pegasus_irq - nonzero urb status received: -71 usb 3-1: pegasus_irq - usb_submit_urb failed with result -19