rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=3cf4/1/0x4000000000000000 softirq=264063/264064 fqs=1 rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P32466/1:b..l P5235/1:b..l P32416/1:b..l P12/1:b..l rcu: (detected by 0, t=10505 jiffies, g=241497, q=395 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 32462 Comm: syz.6.5707 Not tainted 6.16.0-next-20250808-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:_raw_spin_unlock_irqrestore+0x0/0x110 kernel/locking/spinlock.c:193 Code: cc cc cc cc e8 31 48 b6 f5 5b e9 db 4d 00 00 cc 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1e fa 55 48 89 e5 41 57 41 56 41 54 53 48 83 e4 e0 48 83 ec RSP: 0018:ffffc90000a08c80 EFLAGS: 00000046 RAX: 0000000000000000 RBX: ffff888058ef3340 RCX: 0000000000000001 RDX: 0000000000000001 RSI: 0000000000000802 RDI: ffffffff99cec090 RBP: ffff888058b1be80 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff5200014116c R12: ffff888058b1be88 R13: ffff888058b1be70 R14: dffffc0000000000 R15: 1ffff1100b1637d0 FS: 00007f1d7f23b6c0(0000) GS:ffff888125d15000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f1302f72020 CR3: 000000002cdba000 CR4: 00000000003526f0 DR0: 0000000002000000 DR1: 0000000000000003 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: debug_object_activate+0x2e2/0x420 lib/debugobjects.c:836 debug_hrtimer_activate kernel/time/hrtimer.c:445 [inline] debug_activate kernel/time/hrtimer.c:484 [inline] enqueue_hrtimer+0x30/0x3a0 kernel/time/hrtimer.c:1088 __run_hrtimer kernel/time/hrtimer.c:1778 [inline] __hrtimer_run_queues+0x656/0xc60 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline] __sysvec_apic_timer_interrupt+0x108/0x410 arch/x86/kernel/apic/apic.c:1056 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1050 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:finish_task_switch+0x26b/0x950 kernel/sched/core.c:5225 Code: 0f 84 3c 01 00 00 48 85 db 0f 85 63 01 00 00 e9 27 05 00 00 4c 8b 75 d0 4c 89 e7 e8 4f 67 ec 09 e8 ba 45 36 00 fb 4c 8b 65 c0 <49> 8d bc 24 18 16 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0 RSP: 0018:ffffc90004c17538 EFLAGS: 00000282 RAX: 8160bfc4f3b2bc00 RBX: 0000000000000000 RCX: 8160bfc4f3b2bc00 RDX: 0000000000000000 RSI: ffffffff8d9b8efe RDI: ffffffff8be34700 RBP: ffffc90004c17590 R08: ffffffff8fa39a37 R09: 1ffffffff1f47346 R10: dffffc0000000000 R11: fffffbfff1f47347 R12: ffff88802c73bc00 R13: dffffc0000000000 R14: ffff88801ce95a00 R15: ffff8880b873ab58 context_switch kernel/sched/core.c:5360 [inline] __schedule+0x17a0/0x4cc0 kernel/sched/core.c:6961 __schedule_loop kernel/sched/core.c:7043 [inline] schedule+0x165/0x360 kernel/sched/core.c:7058 schedule_timeout+0x9a/0x270 kernel/time/sleep_timeout.c:75 do_wait_for_common kernel/sched/completion.c:100 [inline] __wait_for_common kernel/sched/completion.c:121 [inline] wait_for_common kernel/sched/completion.c:132 [inline] wait_for_completion+0x2bf/0x5d0 kernel/sched/completion.c:153 rdmsr_safe_on_cpu+0x150/0x230 arch/x86/lib/msr-smp.c:181 msr_read+0x14d/0x250 arch/x86/kernel/msr.c:66 vfs_read+0x200/0xa30 fs/read_write.c:570 ksys_read+0x145/0x250 fs/read_write.c:715 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f1d7e38ebe9 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:00007f1d7f23b038 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00007f1d7e5b5fa0 RCX: 00007f1d7e38ebe9 RDX: 0000000000018ff8 RSI: 0000200000019680 RDI: 0000000000000003 RBP: 00007f1d7e411e19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f1d7e5b6038 R14: 00007f1d7e5b5fa0 R15: 00007ffc4547ed38 task:kworker/u8:0 state:R running task stack:19768 pid:12 tgid:12 ppid:2 task_flags:0x4208060 flags:0x00004000 Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7288 irqentry_exit+0x6f/0x90 kernel/entry/common.c:197 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:707 RIP: 0010:__orc_find arch/x86/kernel/unwind_orc.c:99 [inline] RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:227 [inline] RIP: 0010:unwind_next_frame+0x1334/0x2390 arch/x86/kernel/unwind_orc.c:494 Code: 0f b6 04 08 84 c0 75 27 49 63 07 4c 01 f8 49 8d 4f 04 4c 39 e0 48 0f 46 e9 49 8d 47 fc 48 0f 47 d8 4d 0f 46 ef 48 39 dd 76 a2 7b ef ff ff 44 89 f9 80 e1 07 80 c1 03 38 c1 7c cc 4c 89 ff 48 RSP: 0018:ffffc900001174d8 EFLAGS: 00000202 RAX: ffffffff8fb6b9e0 RBX: ffffffff8fb6b9e4 RCX: ffffffff8fb6b9e8 RDX: ffffffff8fb6b9dc RSI: ffffffff903257a4 RDI: ffffffff8be346a0 RBP: ffffffff8fb6b9e8 R08: 0000000000000003 R09: ffffffff8172c195 R10: ffffc900001175f8 R11: ffffffff81ac40a0 R12: ffffffff8167ea78 R13: ffffffff8fb6b9e4 R14: ffffc900001175a8 R15: ffffffff8fb6b9e4 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 unpoison_slab_object mm/kasan/common.c:330 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:356 kasan_slab_alloc include/linux/kasan.h:250 [inline] slab_post_alloc_hook mm/slub.c:4180 [inline] slab_alloc_node mm/slub.c:4229 [inline] kmem_cache_alloc_noprof+0x1c1/0x3c0 mm/slub.c:4236 skb_clone+0x212/0x3a0 net/core/skbuff.c:2049 batadv_iv_ogm_send_to_if net/batman-adv/bat_iv_ogm.c:387 [inline] batadv_iv_ogm_emit net/batman-adv/bat_iv_ogm.c:420 [inline] batadv_iv_send_outstanding_bat_ogm_packet+0x5b5/0x7e0 net/batman-adv/bat_iv_ogm.c:1702 process_one_work kernel/workqueue.c:3236 [inline] process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 task:syz.8.5696 state:R running task stack:25096 pid:32416 tgid:32416 ppid:31987 task_flags:0x40044c flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7288 irqentry_exit+0x6f/0x90 kernel/entry/common.c:197 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:707 RIP: 0010:__read_once_word_nocheck+0x3/0x10 include/asm-generic/rwonce.h:69 Code: b0 00 48 ba 00 00 00 00 00 fc ff df e9 88 fc ff ff 66 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 48 8b 07 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffc90003d8f350 EFLAGS: 00000202 RAX: 00007f5009bc14a5 RBX: ffffc90003d88000 RCX: 1ffff920007b1e01 RDX: ffffc90003d8f438 RSI: 0000000000000003 RDI: ffffc90003d8ffd8 RBP: ffffc90003d90000 R08: 0000000000000022 R09: ffffffff8172c195 R10: ffffc90003d8f478 R11: ffffffff81ac40a0 R12: ffffc90003d8ff58 R13: 1ffff920007b1e86 R14: ffffc90003d8f428 R15: 1ffff920007b1e87 deref_stack_regs arch/x86/kernel/unwind_orc.c:421 [inline] unwind_next_frame+0xe39/0x2390 arch/x86/kernel/unwind_orc.c:596 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:47 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:548 slab_free_hook mm/slub.c:2378 [inline] slab_free mm/slub.c:4680 [inline] kmem_cache_free+0x2f6/0x400 mm/slub.c:4782 exit_mmap+0x53f/0xb50 mm/mmap.c:1305 __mmput+0x118/0x420 kernel/fork.c:1130 exit_mm+0x1da/0x2c0 kernel/exit.c:582 do_exit+0x648/0x2300 kernel/exit.c:949 do_group_exit+0x21c/0x2d0 kernel/exit.c:1102 get_signal+0x1286/0x1340 kernel/signal.c:3034 arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop+0x75/0x110 kernel/entry/common.c:40 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline] do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f5009bc14a5 RSP: 002b:00007ffe4e16f630 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6 RAX: 0000000000000000 RBX: 0000000000000005 RCX: 00007f5009bc14a5 RDX: 00007ffe4e16f670 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000003 R08: 0000000000000000 R09: 000000000002a674 R10: 0000000000000000 R11: 0000000000000293 R12: 000000000033fed1 R13: 00007ffe4e16f790 R14: ffffffffffffffff R15: 00007ffe4e16f7b0 task:udevd state:R running task stack:22856 pid:5235 tgid:5235 ppid:1 task_flags:0x400140 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:7145 preempt_schedule+0xae/0xc0 kernel/sched/core.c:7169 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] _raw_spin_unlock_irqrestore+0xfd/0x110 kernel/locking/spinlock.c:194 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline] __wake_up_common_lock+0x190/0x1f0 kernel/sched/wait.c:127 sock_def_readable+0x1fb/0x550 net/core/sock.c:3564 __netlink_sendskb net/netlink/af_netlink.c:1265 [inline] netlink_sendskb+0xa1/0x140 net/netlink/af_netlink.c:1271 netlink_unicast+0x397/0x9e0 net/netlink/af_netlink.c:1361 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:714 [inline] __sock_sendmsg+0x219/0x270 net/socket.c:729 ____sys_sendmsg+0x505/0x830 net/socket.c:2614 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668 __sys_sendmsg net/socket.c:2700 [inline] __do_sys_sendmsg net/socket.c:2705 [inline] __se_sys_sendmsg net/socket.c:2703 [inline] __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2703 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb3de0a7407 RSP: 002b:00007ffd29b87570 EFLAGS: 00000202 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007fb3de8af880 RCX: 00007fb3de0a7407 RDX: 0000000000000000 RSI: 00007ffd29b875d0 RDI: 0000000000000004 RBP: 000055ff0f74c510 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00000000000000b6 R13: 000055ff0f74c9e0 R14: 0000000000000000 R15: 0000000000000000 task:syz.1.5709 state:R running task stack:26920 pid:32466 tgid:32466 ppid:29989 task_flags:0x40004c flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:7145 preempt_schedule+0xae/0xc0 kernel/sched/core.c:7169 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline] _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:391 [inline] zap_pte_range mm/memory.c:1756 [inline] zap_pmd_range mm/memory.c:1818 [inline] zap_pud_range mm/memory.c:1847 [inline] zap_p4d_range mm/memory.c:1868 [inline] unmap_page_range+0x3a79/0x4370 mm/memory.c:1889 unmap_single_vma mm/memory.c:1932 [inline] unmap_vmas+0x399/0x580 mm/memory.c:1976 exit_mmap+0x248/0xb50 mm/mmap.c:1280 __mmput+0x118/0x420 kernel/fork.c:1130 exit_mm+0x1da/0x2c0 kernel/exit.c:582 do_exit+0x648/0x2300 kernel/exit.c:949 do_group_exit+0x21c/0x2d0 kernel/exit.c:1102 __do_sys_exit_group kernel/exit.c:1113 [inline] __se_sys_exit_group kernel/exit.c:1111 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1111 x64_sys_call+0x21f7/0x2200 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f1302f8ebe9 RSP: 002b:00007ffff5539ce8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f1302f8ebe9 RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007ffff5539d4c R08: 0000000df5539ddf R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000246 R12: 00000000000000dd R13: 0000000000000000 R14: 000000000033eb97 R15: 00007ffff5539da0 rcu: rcu_preempt kthread starved for 10500 jiffies! g241497 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:26792 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961 __schedule_loop kernel/sched/core.c:7043 [inline] schedule+0x165/0x360 kernel/sched/core.c:7058 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+0x3f9/0x770 arch/x86/kernel/process.c:148 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: 1171 Comm: kworker/u8:9 Not tainted 6.16.0-next-20250808-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Workqueue: events_unbound toggle_allocation_gate RIP: 0010:native_pause arch/x86/include/asm/vdso/processor.h:13 [inline] RIP: 0010:cpu_relax arch/x86/include/asm/vdso/processor.h:18 [inline] RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xd31/0x12d0 kernel/smp.c:877 Code: 00 00 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 b6 62 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 61 5e 0b 00 eb 38 90 42 0f b6 04 2b 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 RSP: 0018:ffffc9000424f660 EFLAGS: 00000293 RAX: ffffffff81b4557b RBX: 1ffff110170e7f61 RCX: ffff888026bd8000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc9000424f7e0 R08: ffffffff8fa39a37 R09: 1ffffffff1f47346 R10: dffffc0000000000 R11: fffffbfff1f47347 R12: ffff8880b873fb08 R13: dffffc0000000000 R14: ffff8880b863b1c0 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff888125c15000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c31c270 CR3: 000000000df36000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 000000000000000e DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1044 on_each_cpu include/linux/smp.h:71 [inline] smp_text_poke_sync_each_cpu arch/x86/kernel/alternative.c:2653 [inline] smp_text_poke_batch_finish+0x5f9/0x1130 arch/x86/kernel/alternative.c:2863 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146 static_key_enable_cpuslocked+0x128/0x250 kernel/jump_label.c:210 static_key_enable+0x1a/0x20 kernel/jump_label.c:223 toggle_allocation_gate+0xad/0x240 mm/kfence/core.c:850 process_one_work kernel/workqueue.c:3236 [inline] process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245