rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=e70c/1/0x4000000000000000 softirq=27097/27098 fqs=31 rcu: (detected by 0, t=10504 jiffies, g=33089, q=175 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 9563 Comm: syz.1.1354 Not tainted 6.6.102-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:constant_test_bit arch/x86/include/asm/bitops.h:207 [inline] RIP: 0010:arch_test_bit arch/x86/include/asm/bitops.h:239 [inline] RIP: 0010:tif_need_resched include/linux/thread_info.h:184 [inline] RIP: 0010:tracing_gen_ctx_irq_test+0x97/0x140 kernel/trace/trace.c:2707 Code: 00 00 44 89 e6 81 e6 00 fe 00 00 44 0f 44 f0 31 ff e8 4d 82 fc ff 65 48 8b 1d 75 ad 7a 7e 48 89 d8 48 c1 e8 03 42 80 3c 38 00 <74> 08 48 89 df e8 af c5 53 00 48 8b 03 d1 e8 83 e0 04 41 09 c6 65 RSP: 0018:ffffc90005666bd0 EFLAGS: 00000046 RAX: 1ffff1100fda1000 RBX: ffff88807ed08000 RCX: 0000000000000002 RDX: ffff88807ed08000 RSI: 0000000000000400 RDI: 0000000000000000 RBP: 0000000000000001 R08: ffffc90005666e8f R09: 0000000000000000 R10: ffffc90005666e80 R11: fffff52000accdd2 R12: 0000000000000402 R13: 1ffff92000accd84 R14: 0000000000000081 R15: dffffc0000000000 FS: 00007fea17de66c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000001340 CR3: 000000007795c000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: tracing_gen_ctx_flags include/linux/trace_events.h:195 [inline] tracing_gen_ctx include/linux/trace_events.h:202 [inline] perf_trace_buf_update+0xa0/0x220 kernel/trace/trace_event_perf.c:429 perf_tp_event+0xf9/0x13a0 kernel/events/core.c:10329 perf_trace_run_bpf_submit+0xf4/0x1c0 kernel/events/core.c:10267 perf_trace_preemptirq_template+0x281/0x340 include/trace/events/preemptirq.h:14 trace_irq_enable+0xbf/0xe0 include/trace/events/preemptirq.h:40 trace_hardirqs_on+0x18/0x40 kernel/trace/trace_preemptirq.c:56 asm_sysvec_irq_work+0x1a/0x20 arch/x86/include/asm/idtentry.h:723 RIP: 0010:rcu_read_unlock_special+0x88/0x4c0 kernel/rcu/tree_plugin.h:682 Code: f1 f1 f1 00 f2 f2 f2 4a 89 04 2b 66 42 c7 44 2b 09 f3 f3 42 c6 44 2b 0b f3 65 44 8b 35 39 58 93 7e 41 f7 c6 00 00 f0 00 74 45 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 66 42 c7 44 2b RSP: 0018:ffffc90005667160 EFLAGS: 00000206 RAX: a909b389dccd7300 RBX: 1ffff92000acce34 RCX: a909b389dccd7300 RDX: dffffc0000000000 RSI: ffffffff8aaab9c0 RDI: ffffffff8afc66c0 RBP: ffffc90005667260 R08: ffffffff90da35ef R09: 1ffffffff21b46bd R10: dffffc0000000000 R11: fffffbfff21b46be R12: ffffffff8cd35400 R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000002 __rcu_read_unlock+0x7c/0xd0 kernel/rcu/tree_plugin.h:426 rcu_read_unlock include/linux/rcupdate.h:818 [inline] hsr_forward_skb+0x1803/0x2120 net/hsr/hsr_forward.c:625 hsr_dev_xmit+0x13d/0x200 net/hsr/hsr_device.c:220 __netdev_start_xmit include/linux/netdevice.h:4943 [inline] netdev_start_xmit include/linux/netdevice.h:4957 [inline] xmit_one net/core/dev.c:3607 [inline] dev_hard_start_xmit+0x246/0x740 net/core/dev.c:3623 __dev_queue_xmit+0x1a64/0x35a0 net/core/dev.c:4413 packet_snd net/packet/af_packet.c:3137 [inline] packet_sendmsg+0x3b47/0x4d30 net/packet/af_packet.c:3169 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg net/socket.c:745 [inline] ____sys_sendmsg+0x5bf/0x950 net/socket.c:2595 ___sys_sendmsg+0x220/0x290 net/socket.c:2649 __sys_sendmsg net/socket.c:2678 [inline] __do_sys_sendmsg net/socket.c:2687 [inline] __se_sys_sendmsg+0x1a5/0x270 net/socket.c:2685 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fea16f8ebe9 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:00007fea17de6038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007fea171b5fa0 RCX: 00007fea16f8ebe9 RDX: 0000000000000000 RSI: 0000200000000fc0 RDI: 000000000000000b RBP: 00007fea17011e19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fea171b6038 R14: 00007fea171b5fa0 R15: 00007ffeed0fbc28 rcu: rcu_preempt kthread starved for 10350 jiffies! g33089 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:26568 pid:17 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5380 [inline] __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699 schedule+0xbd/0x170 kernel/sched/core.c:6773 schedule_timeout+0x160/0x280 kernel/time/timer.c:2167 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1866 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.6.102-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:148 Code: cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d e3 e6 3a 00 f3 0f 1e fa fb f4 cc cc cc cc cc cc cc cc cc cc cc cc 66 0f 1f 00 55 41 57 41 56 RSP: 0018:ffffc900000077f8 EFLAGS: 00000246 RAX: ffffffff813a13aa RBX: 0000000000000003 RCX: ffffffff8ca93380 RDX: 0000000000000100 RSI: ffffffff8aaab9c0 RDI: ffffffff8afc66c0 RBP: ffffc900000078d0 R08: ffffffff90da35ef R09: 1ffffffff21b46bd R10: dffffc0000000000 R11: fffffbfff21b46be R12: dffffc0000000000 R13: 0000000000000200 R14: 0000000000000003 R15: 1ffff92000000f04 FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2e822ff8 CR3: 0000000064139000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline] kvm_wait+0x22f/0x290 arch/x86/kernel/kvm.c:1058 pv_wait arch/x86/include/asm/paravirt.h:598 [inline] pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline] __pv_queued_spin_lock_slowpath+0x61a/0x9d0 kernel/locking/qspinlock.c:511 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:586 [inline] queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline] queued_spin_lock include/asm-generic/qspinlock.h:114 [inline] do_raw_spin_lock+0x24e/0x2c0 kernel/locking/spinlock_debug.c:115 spin_lock_bh include/linux/spinlock.h:356 [inline] send_hsr_supervision_frame+0x210/0xa60 net/hsr/hsr_device.c:300 hsr_announce+0x192/0x340 net/hsr/hsr_device.c:379 call_timer_fn+0x16e/0x530 kernel/time/timer.c:1700 expire_timers kernel/time/timer.c:1751 [inline] __run_timers+0x52d/0x7d0 kernel/time/timer.c:2022 run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2035 handle_softirqs+0x280/0x820 kernel/softirq.c:578 __do_softirq kernel/softirq.c:612 [inline] invoke_softirq kernel/softirq.c:452 [inline] __irq_exit_rcu+0xc7/0x190 kernel/softirq.c:661 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline] sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:148 Code: cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d e3 e6 3a 00 f3 0f 1e fa fb f4 cc cc cc cc cc cc cc cc cc cc cc cc 66 0f 1f 00 55 41 57 41 56 RSP: 0018:ffffffff8ca07d80 EFLAGS: 000002c6 RAX: f1f8fcb3deb80e00 RBX: ffffffff8161914b RCX: f1f8fcb3deb80e00 RDX: 0000000000000001 RSI: ffffffff8aaab9c0 RDI: ffffffff8afc66c0 RBP: ffffffff8ca07eb8 R08: ffff8880b8e36d4b R09: 1ffff110171c6da9 R10: dffffc0000000000 R11: ffffed10171c6daa R12: ffffffff8e4a8828 R13: 0000000000000000 R14: 0000000000000000 R15: 1ffffffff1952670 arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:753 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97 cpuidle_idle_call kernel/sched/idle.c:170 [inline] do_idle+0x1eb/0x510 kernel/sched/idle.c:282 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:380 rest_init+0x2e2/0x300 init/main.c:732 arch_call_rest_init+0xe/0x10 init/main.c:829 start_kernel+0x459/0x4e0 init/main.c:1074 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:555 x86_64_start_kernel+0x60/0x60 arch/x86/kernel/head64.c:536 secondary_startup_64_no_verify+0x179/0x17b