rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P3361/3:b..l P8505/1:b..l rcu: (detected by 0, t=10502 jiffies, g=29109, q=1175 ncpus=2) task:syz.3.722 state:D stack:24872 pid:8505 tgid:8505 ppid:5586 task_flags:0x400040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5526 [inline] __schedule+0x16d9/0x5700 kernel/sched/core.c:7277 __schedule_loop kernel/sched/core.c:7354 [inline] schedule_rtlock+0x30/0x70 kernel/sched/core.c:7433 rtlock_slowlock_locked+0x35c9/0x3c20 kernel/locking/rtmutex.c:1895 rtlock_slowlock kernel/locking/rtmutex.c:1922 [inline] rtlock_lock kernel/locking/spinlock_rt.c:43 [inline] __rt_spin_lock kernel/locking/spinlock_rt.c:49 [inline] rt_spin_lock+0x165/0x400 kernel/locking/spinlock_rt.c:57 spin_lock_bh include/linux/spinlock_rt.h:90 [inline] lock_sock_nested+0x7e/0x130 net/core/sock.c:3849 lock_sock include/net/sock.h:1713 [inline] tipc_release+0xc4/0x2500 net/tipc/socket.c:639 __sock_release+0xa0/0x1f0 net/socket.c:735 sock_close+0x1c/0x30 net/socket.c:1526 __fput+0x42a/0xa80 fs/file_table.c:512 task_work_run+0x1d9/0x270 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:70 [inline] exit_to_user_mode_loop+0x204/0x770 kernel/entry/common.c:101 __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:343 [inline] do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb408c4e159 RSP: 002b:00007ffff9569a68 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007fb408ed7da0 RCX: 00007fb408c4e159 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007fb408ed7da0 R08: 0000000000000006 R09: 0000000000000000 R10: 00007fb408ed7cb0 R11: 0000000000000246 R12: 000000000006316e R13: 00007fb408ed609c R14: 0000000000062eac R15: 00007fb408ed6090 task:kworker/u8:12 state:R running task stack:20504 pid:3361 tgid:3361 ppid:2 task_flags:0x4208060 flags:0x00080000 Workqueue: tipc_send tipc_conn_send_work Call Trace: context_switch kernel/sched/core.c:5526 [inline] __schedule+0x16d9/0x5700 kernel/sched/core.c:7277 preempt_schedule_irq+0x4b/0x90 kernel/sched/core.c:7599 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x14f/0x910 kernel/entry/common.c:167 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:679 RIP: 0010:lock_acquire+0x232/0x350 kernel/locking/lockdep.c:5947 Code: ff ff ff e8 20 41 b5 09 f7 44 24 10 00 02 00 00 0f 84 38 ff ff ff 65 48 8b 05 52 7c 03 11 48 3b 44 24 50 75 33 fb 48 83 c4 58 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 48 8d 3d 87 3a 13 RSP: 0018:ffffc9000f666948 EFLAGS: 00000286 RAX: dda3612a5535ab00 RBX: 0000000000000000 RCX: 0000000000000046 RDX: 0000000077b090b0 RSI: ffffffff8dadc083 RDI: ffffffff8bcc2e80 RBP: ffff88802c570000 R08: ffffffff8177e1bf R09: 0000000000000000 R10: ffffc9000f666a88 R11: fffff52001eccd5d R12: ffffffff8e1c3c80 R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000246 rcu_lock_acquire include/linux/rcupdate.h:309 [inline] rcu_read_lock include/linux/rcupdate.h:849 [inline] class_rcu_constructor include/linux/rcupdate.h:1216 [inline] unwind_next_frame+0xac/0x2550 arch/x86/kernel/unwind_orc.c:495 __unwind_start+0x514/0x660 arch/x86/kernel/unwind_orc.c:787 unwind_start arch/x86/include/asm/unwind.h:64 [inline] arch_stack_walk+0xe3/0x150 arch/x86/kernel/stacktrace.c:24 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 unpoison_slab_object mm/kasan/common.c:340 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4683 [inline] slab_alloc_node mm/slub.c:4996 [inline] kmem_cache_alloc_node_noprof+0x3fc/0x660 mm/slub.c:5068 __alloc_skb+0x1db/0x7a0 net/core/skbuff.c:704 alloc_skb_fclone include/linux/skbuff.h:1434 [inline] tipc_buf_acquire net/tipc/msg.c:72 [inline] tipc_msg_create+0x4c/0x4c0 net/tipc/msg.c:104 tipc_group_proto_xmit+0xce/0x790 net/tipc/group.c:710 tipc_group_member_evt+0xd97/0x1270 net/tipc/group.c:894 tipc_sk_proto_rcv+0x2d3/0x1810 net/tipc/socket.c:2175 tipc_sk_filter_rcv+0x3005/0x3240 net/tipc/socket.c:2357 tipc_sk_enqueue net/tipc/socket.c:2450 [inline] tipc_sk_rcv+0x8c4/0x2b30 net/tipc/socket.c:2502 tipc_topsrv_kern_evt net/tipc/topsrv.c:630 [inline] tipc_conn_send_to_sock net/tipc/topsrv.c:286 [inline] tipc_conn_send_work+0x6cd/0xa50 net/tipc/topsrv.c:306 process_one_work kernel/workqueue.c:3396 [inline] process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560 kthread+0x38b/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: rcu_preempt kthread timer wakeup didn't happen for 9339 jiffies! g29109 f0x0 RCU_GP_WAIT_FQS(5) ->state=I rcu: Possible timer handling issue on cpu=1 timer-softirq=16513 rcu: rcu_preempt kthread starved for 9340 jiffies! g29109 f0x0 RCU_GP_WAIT_FQS(5) ->state=I ->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:27784 pid:18 tgid:18 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5526 [inline] __schedule+0x16d9/0x5700 kernel/sched/core.c:7277 __schedule_loop kernel/sched/core.c:7354 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7369 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2122 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2330 kthread+0x38b/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: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 8507 Comm: syz.3.722 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 RIP: 0010:__lock_acquire+0x121/0x2de0 kernel/locking/lockdep.c:5184 Code: 48 01 d1 48 39 cf 74 16 45 31 f6 48 89 df 31 d2 e8 14 f0 ff ff 48 85 c0 0f 84 b9 13 00 00 48 8b 4c 24 08 44 8b b1 08 0c 00 00 <49> 83 fe 30 0f 93 c1 83 3d 71 be 0c 18 00 74 02 31 c9 84 c9 0f 85 RSP: 0018:ffffc9000125f060 EFLAGS: 00000046 RAX: ffffffff934c32a8 RBX: ffffc9000125f9b0 RCX: ffff88802ef70000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff99ae8a20 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001 R10: dffffc0000000000 R11: fffffbfff1f640d0 R12: ffffc9000125f9b0 R13: 0000000000000001 R14: 0000000000000004 R15: 0000000000000000 FS: 00007fb406ea66c0(0000) GS:ffff888125ccb000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fca67b1f12d CR3: 000000005bf14000 CR4: 00000000003526f0 Call Trace: lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:155 [inline] _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:181 rtlock_slowlock kernel/locking/rtmutex.c:1921 [inline] rtlock_lock kernel/locking/spinlock_rt.c:43 [inline] __rt_spin_lock kernel/locking/spinlock_rt.c:49 [inline] rt_spin_lock+0x157/0x400 kernel/locking/spinlock_rt.c:57 spin_lock_bh include/linux/spinlock_rt.h:90 [inline] tipc_skb_peek_port net/tipc/msg.h:1225 [inline] tipc_sk_rcv+0x2c0/0x2b30 net/tipc/socket.c:2496 tipc_node_xmit+0x218/0xf10 net/tipc/node.c:1708 tipc_node_xmit_skb net/tipc/node.c:1773 [inline] tipc_node_distr_xmit+0x2da/0x420 net/tipc/node.c:1788 tipc_group_join+0x571/0x710 net/tipc/group.c:208 tipc_sk_join+0x480/0x6a0 net/tipc/socket.c:3107 tipc_setsockopt+0x73e/0x9a0 net/tipc/socket.c:3205 do_sock_setsockopt+0x17c/0x1b0 net/socket.c:2397 __sys_setsockopt net/socket.c:2422 [inline] __do_sys_setsockopt net/socket.c:2428 [inline] __se_sys_setsockopt net/socket.c:2425 [inline] __x64_sys_setsockopt+0x143/0x1b0 net/socket.c:2425 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb408c4e159 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fb406ea6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 00007fb408ed5fa0 RCX: 00007fb408c4e159 RDX: 0000000000000087 RSI: 000000000000010f RDI: 0000000000000004 RBP: 00007fb408ce506b R08: 0000000000000010 R09: 0000000000000000 R10: 0000200000000440 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fb408ed6038 R14: 00007fb408ed5fa0 R15: 00007ffff9569908