rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P1182/1:b..l P154/1:b..l (detected by 0, t=10502 jiffies, g=8889, q=161) task:kworker/u4:2 state:R running task stack:26368 pid: 154 ppid: 2 flags:0x00004000 Workqueue: bat_events batadv_nc_worker Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11bb/0x4390 kernel/sched/core.c:6395 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6799 irqentry_exit+0x63/0x70 kernel/entry/common.c:432 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 RIP: 0010:lock_acquire+0x1f2/0x3f0 kernel/locking/lockdep.c:5627 Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f6 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b RSP: 0018:ffffc900010cfa40 EFLAGS: 00000206 RAX: 0000000000000001 RBX: 0000000000000000 RCX: a2e0928e9d751600 RDX: 0000000000000000 RSI: ffffffff8a0b2b40 RDI: ffffffff8a59a880 RBP: ffffc900010cfb58 R08: dffffc0000000000 R09: fffffbfff1ff7a19 R10: fffffbfff1ff7a19 R11: 1ffffffff1ff7a18 R12: ffffffff8c11c720 R13: 1ffff92000219f54 R14: 0000000000000246 R15: dffffc0000000000 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313 rcu_read_lock include/linux/rcupdate.h:740 [inline] batadv_nc_process_nc_paths+0xb2/0x350 net/batman-adv/network-coding.c:691 batadv_nc_worker+0x3e5/0x5c0 net/batman-adv/network-coding.c:732 process_one_work+0x863/0x1000 kernel/workqueue.c:2310 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 task:kworker/u4:3 state:R running task stack:23592 pid: 1182 ppid: 2 flags:0x00004000 Workqueue: netns cleanup_net Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11bb/0x4390 kernel/sched/core.c:6395 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6799 irqentry_exit+0x63/0x70 kernel/entry/common.c:432 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 RIP: 0010:lock_acquire+0x1f2/0x3f0 kernel/locking/lockdep.c:5627 Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f6 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b RSP: 0018:ffffc900053e7900 EFLAGS: 00000206 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 738c0576337c6b00 RDX: 0000000000000000 RSI: ffffffff8a0b2b40 RDI: ffffffff8a59a880 RBP: ffffc900053e7a20 R08: dffffc0000000000 R09: fffffbfff1ff7a19 R10: fffffbfff1ff7a19 R11: 1ffffffff1ff7a18 R12: ffffffff8c11c720 R13: 1ffff92000a7cf2c R14: 0000000000000246 R15: dffffc0000000000 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313 rcu_read_lock include/linux/rcupdate.h:740 [inline] inet_twsk_purge+0x119/0x810 net/ipv4/inet_timewait_sock.c:268 ops_exit_list net/core/net_namespace.c:177 [inline] cleanup_net+0x77b/0xb80 net/core/net_namespace.c:635 process_one_work+0x863/0x1000 kernel/workqueue.c:2310 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 rcu: rcu_preempt kthread starved for 10558 jiffies! g8889 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:27584 pid: 15 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11bb/0x4390 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914 rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972 rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 4461 Comm: syz.3.20 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 RIP: 0010:lock_is_held_type+0x4c/0x190 kernel/locking/lockdep.c:5659 Code: 3d 9c 7d c0 03 00 0f 84 03 01 00 00 65 8b 05 cb 28 59 76 85 c0 0f 85 f4 00 00 00 65 48 8b 1d 3b 1f 59 76 83 bb ec 0a 00 00 00 <0f> 85 df 00 00 00 41 89 f7 49 89 fe 48 c7 04 24 00 00 00 00 9c 8f RSP: 0018:ffffc90002f7fad8 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffff888021735940 RCX: ffff888021735940 RDX: 0000000000000000 RSI: 00000000ffffffff RDI: ffffffff8c11c7e0 RBP: 00000000ffffffff R08: 0000000000000000 R09: fffffbfff1778666 R10: fffffbfff1778666 R11: 1ffffffff1778660 R12: dffffc0000000000 R13: 1ffff920005effff R14: ffffffff8a596d20 R15: 0000000000000000 FS: 0000555558be8500(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000020000006b000 CR3: 0000000074890000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_is_held include/linux/lockdep.h:287 [inline] ___might_sleep+0xf2/0x600 kernel/sched/core.c:9624 __might_fault+0x6b/0x110 mm/memory.c:5354 _copy_to_user+0x29/0x130 lib/usercopy.c:35 copy_to_user include/linux/uaccess.h:200 [inline] copy_siginfo_to_user+0x20/0x80 kernel/signal.c:3367 __setup_rt_frame arch/x86/kernel/signal.c:490 [inline] setup_rt_frame arch/x86/kernel/signal.c:780 [inline] handle_signal arch/x86/kernel/signal.c:824 [inline] arch_do_signal_or_restart+0xd56/0x1300 arch/x86/kernel/signal.c:869 handle_signal_work kernel/entry/common.c:154 [inline] exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7fb8404f4fc9 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:00007ffc46c54e58 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 00007fb84074bfa0 RCX: 00007fb8404f4fc9 RDX: 000020000006b000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007fb840577f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fb84074bfa0 R14: 00007fb84074bfa0 R15: 0000000000000004 sched: RT throttling activated