rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P2/1:b..l P13136/1:b..l P4981/1:b..l rcu: (detected by 1, t=10502 jiffies, g=71961, q=889 ncpus=2) task:klogd state:R running task stack:23288 pid:4981 tgid:4981 ppid:1 task_flags:0x400100 flags:0x00080800 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_irqrestore include/linux/spinlock_api_smp.h:179 [inline] _raw_spin_unlock_irqrestore+0x74/0x80 kernel/locking/spinlock.c:198 spin_unlock_irqrestore include/linux/spinlock.h:408 [inline] __wake_up_common_lock+0x190/0x1f0 kernel/sched/wait.c:127 sock_def_readable+0x1eb/0x550 net/core/sock.c:3614 unix_dgram_sendmsg+0xdfd/0x18d0 net/unix/af_unix.c:2297 sock_sendmsg_nosec net/socket.c:787 [inline] __sock_sendmsg net/socket.c:802 [inline] __sys_sendto+0x672/0x710 net/socket.c:2265 __do_sys_sendto net/socket.c:2272 [inline] __se_sys_sendto net/socket.c:2268 [inline] __x64_sys_sendto+0xde/0x100 net/socket.c:2268 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fe5f2299407 RSP: 002b:00007ffdaf947b80 EFLAGS: 00000202 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007fe5f2149c80 RCX: 00007fe5f2299407 RDX: 0000000000000093 RSI: 00007ffdaf947cc0 RDI: 0000000000000003 RBP: 00007ffdaf9480f0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000004000 R11: 0000000000000202 R12: 00007ffdaf948108 R13: 00007ffdaf947cc0 R14: 0000000000000078 R15: 00007ffdaf947cc0 task:syz.3.1954 state:R running task stack:26472 pid:13136 tgid:13115 ppid:5632 task_flags:0x40044c flags:0x00080003 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:539 [inline] irqentry_exit+0x14f/0x8b0 kernel/entry/common.c:164 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lockdep_enabled kernel/locking/lockdep.c:118 [inline] RIP: 0010:lock_acquire+0x8b/0x350 kernel/locking/lockdep.c:5844 Code: 0f 84 ca 01 00 00 83 3d 72 b9 8e 0e 00 0f 84 d3 00 00 00 48 8b b4 24 90 00 00 00 4c 89 ef e8 2c 40 8f 00 83 3d 55 b9 8e 0e 00 <0f> 84 ce 00 00 00 65 8b 05 18 e1 96 11 85 c0 0f 85 bf 00 00 00 65 RSP: 0018:ffffc90003d97178 EFLAGS: 00000202 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000080000001 RDX: 0000000000000000 RSI: ffffffff8176e273 RDI: 1ffffffff1d2b984 RBP: ffffffff8176e256 R08: 0000000000000000 R09: 0000000000000000 R10: dffffc0000000000 R11: ffffffff81b0e0e0 R12: 0000000000000002 R13: ffffffff8e95cc20 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:300 [inline] rcu_read_lock include/linux/rcupdate.h:838 [inline] class_rcu_constructor include/linux/rcupdate.h:1181 [inline] unwind_next_frame+0xc3/0x2550 arch/x86/kernel/unwind_orc.c:495 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 save_stack+0x122/0x230 mm/page_owner.c:165 __reset_page_owner+0x71/0x1f0 mm/page_owner.c:320 reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1397 [inline] __free_frozen_pages+0xc1c/0xd30 mm/page_alloc.c:2938 __slab_free+0x274/0x2c0 mm/slub.c:5613 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_kmalloc+0x22/0xb0 mm/kasan/common.c:406 kasan_kmalloc include/linux/kasan.h:263 [inline] __do_kmalloc_node mm/slub.c:5296 [inline] __kmalloc_noprof+0x35c/0x760 mm/slub.c:5308 kmalloc_noprof include/linux/slab.h:954 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] kobject_get_path+0xc5/0x2f0 lib/kobject.c:161 kobject_uevent_env+0x2a1/0x9e0 lib/kobject_uevent.c:548 __device_release_driver drivers/base/dd.c:1364 [inline] device_release_driver_internal+0x76f/0x870 drivers/base/dd.c:1375 driver_detach+0x1f3/0x2d0 drivers/base/dd.c:1438 bus_remove_driver+0x226/0x320 drivers/base/bus.c:825 usb_gadget_unregister_driver+0x4e/0x70 drivers/usb/gadget/udc/core.c:1752 raw_release+0xd7/0x260 drivers/usb/gadget/legacy/raw_gadget.c:463 __fput+0x44f/0xa60 fs/file_table.c:510 task_work_run+0x1d9/0x270 kernel/task_work.c:233 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x70f/0x22c0 kernel/exit.c:976 do_group_exit+0x21b/0x2d0 kernel/exit.c:1119 get_signal+0x1284/0x1330 kernel/signal.c:3037 arch_do_signal_or_restart+0xbc/0x840 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline] exit_to_user_mode_loop+0xa9/0x680 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] do_syscall_64+0x353/0x580 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f15ddd9ce59 RSP: 002b:00007f15decbd0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007f15de016098 RCX: 00007f15ddd9ce59 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f15de016098 RBP: 00007f15de016090 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f15de016128 R14: 00007fffeee8e500 R15: 00007fffeee8e5e8 task:kthreadd state:R running task stack:25672 pid:2 tgid:2 ppid:0 task_flags:0x208040 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:539 [inline] irqentry_exit+0x14f/0x8b0 kernel/entry/common.c:164 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_is_held_type+0x106/0x150 kernel/locking/lockdep.c:5945 Code: 1a 00 00 b8 ff ff ff ff 65 0f c1 05 64 1d 91 07 83 f8 01 75 25 9c 58 a9 00 02 00 00 75 39 41 f7 c4 00 02 00 00 74 01 fb 89 d8 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 96 d8 68 f5 cc 90 0f 0b 90 48 c7 RSP: 0018:ffffc900000775b8 EFLAGS: 00000206 RAX: 0000000000000001 RBX: 0000000000000001 RCX: 0000000000000046 RDX: 0000000000000000 RSI: ffffffff8e216dde RDI: ffffffff8c28b8e0 RBP: 00000000ffffffff R08: ffffffff823ad05e R09: ffffffff8e95cc20 R10: 000000000000000d R11: ffffffff81b0e0e0 R12: 0000000000000246 R13: ffff88801d2e3e00 R14: ffffffff8e95cc20 R15: 0000000000000001 lookup_page_ext mm/page_ext.c:258 [inline] page_ext_lookup+0xe7/0x180 mm/page_ext.c:513 page_ext_iter_begin include/linux/page_ext.h:133 [inline] __update_page_owner_free_handle+0x103/0x470 mm/page_owner.c:284 __reset_page_owner+0x85/0x1f0 mm/page_owner.c:321 reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1397 [inline] __free_frozen_pages+0xc1c/0xd30 mm/page_alloc.c:2938 __slab_free+0x274/0x2c0 mm/slub.c:5613 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_kmalloc+0x22/0xb0 mm/kasan/common.c:406 kasan_kmalloc include/linux/kasan.h:263 [inline] __kmalloc_cache_noprof+0x31c/0x660 mm/slub.c:5420 kmalloc_noprof include/linux/slab.h:950 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] set_kthread_struct+0xbb/0x340 kernel/kthread.c:107 copy_process+0x1835/0x4440 kernel/fork.c:2193 kernel_clone+0x2d7/0x940 kernel/fork.c:2722 kernel_thread+0x13f/0x1b0 kernel/fork.c:2783 create_kthread kernel/kthread.c:459 [inline] kthreadd+0x4ec/0x6e0 kernel/kthread.c:817 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: rcu_preempt kthread starved for 9912 jiffies! g71961 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:27856 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+0x389/0x470 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: 1 UID: 0 PID: 0 Comm: swapper/1 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: cb 7e 02 e9 ee df 68 f5 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 e3 01 22 00 fb f4 c7 df 68 f5 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 RSP: 0018:ffffc90000197e20 EFLAGS: 00000246 RAX: 000000000277681d RBX: ffffffff819a845a RCX: 0000000080000001 RDX: 0000000000000001 RSI: ffffffff8dfa4398 RDI: ffffffff8c28b8e0 RBP: ffffc90000197f10 R08: ffff8880b87339db R09: 1ffff110170e673b R10: dffffc0000000000 R11: ffffed10170e673c R12: 0000000000000001 R13: 1ffff11003b53000 R14: 0000000000000001 R15: 1ffff11003b53000 FS: 0000000000000000(0000) GS:ffff88812539c000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffce489ac90 CR3: 0000000066b1b000 CR4: 0000000000350ef0 DR0: 0000000000000004 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 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 start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:312 common_startup_64+0x13e/0x147