rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=e9c4/1/0x4000000000000000 softirq=25935/25936 fqs=3 rcu: (detected by 1, t=10502 jiffies, g=15913, q=644 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 6591 Comm: syz.0.16 Not tainted 6.15.0-rc5-syzkaller-01021-g0b28182c73a3 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:arch_atomic_read arch/x86/include/asm/atomic.h:23 [inline] RIP: 0010:raw_atomic_read include/linux/atomic/atomic-arch-fallback.h:457 [inline] RIP: 0010:rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline] RIP: 0010:rcu_is_watching+0x5a/0xb0 kernel/rcu/tree.c:736 Code: f0 48 c1 e8 03 42 80 3c 38 00 74 08 4c 89 f7 e8 9c cd 7a 00 48 c7 c3 58 2b 77 92 49 03 1e 48 89 d8 48 c1 e8 03 42 0f b6 04 38 <84> c0 75 34 8b 03 65 ff 0d 49 08 cf 10 74 11 83 e0 04 c1 e8 02 5b RSP: 0018:ffffc90000007bd8 EFLAGS: 00000802 RAX: 0000000000000000 RBX: ffff8880b8832b58 RCX: efa3ef11a96b2700 RDX: 0000000000010000 RSI: ffffffff8bc1d480 RDI: ffffffff8bc1d440 RBP: ffff888041d9b550 R08: ffff888041d9b487 R09: 1ffff110083b3690 R10: dffffc0000000000 R11: ffffed10083b3691 R12: ffff888028668340 R13: ffffffff8977e16f R14: ffffffff8d975c10 R15: dffffc0000000000 FS: 00007f51588dd6c0(0000) GS:ffff8881260c0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020001480 CR3: 00000000290c6000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: trace_lock_release include/trace/events/lock.h:69 [inline] lock_release+0x4b/0x3e0 kernel/locking/lockdep.c:5877 __raw_spin_unlock include/linux/spinlock_api_smp.h:141 [inline] _raw_spin_unlock+0x16/0x50 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:391 [inline] advance_sched+0x99f/0xc90 net/sched/sch_taprio.c:981 __run_hrtimer kernel/time/hrtimer.c:1761 [inline] __hrtimer_run_queues+0x529/0xc60 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline] __sysvec_apic_timer_interrupt+0x108/0x410 arch/x86/kernel/apic/apic.c:1055 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0xa8/0x110 kernel/locking/spinlock.c:194 Code: 74 05 e8 cb a2 6d f6 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4f f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 f3 24 37 f6 65 8b 05 5c 55 1c 07 85 c0 74 40 48 c7 04 24 0e 36 RSP: 0018:ffffc90002e6ee60 EFLAGS: 00000206 RAX: efa3ef11a96b2700 RBX: 0000000000000a06 RCX: efa3ef11a96b2700 RDX: 0000000000000002 RSI: ffffffff8d7517fa RDI: 0000000000000001 RBP: ffffc90002e6eef0 R08: ffffffff8f7f2d77 R09: 1ffffffff1efe5ae R10: dffffc0000000000 R11: fffffbfff1efe5af R12: dffffc0000000000 R13: ffff8880286680f0 R14: ffff8880286682e8 R15: 1ffff920005cddcc spin_unlock_irqrestore include/linux/spinlock.h:406 [inline] taprio_change+0x3119/0x3f60 net/sched/sch_taprio.c:1972 taprio_init+0x959/0xbd0 net/sched/sch_taprio.c:2112 qdisc_create+0x7a9/0xea0 net/sched/sch_api.c:1333 __tc_modify_qdisc net/sched/sch_api.c:1758 [inline] tc_modify_qdisc+0x1426/0x2010 net/sched/sch_api.c:1822 rtnetlink_rcv_msg+0x779/0xb70 net/core/rtnetlink.c:6964 netlink_rcv_skb+0x219/0x490 net/netlink/af_netlink.c:2534 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline] netlink_unicast+0x758/0x8d0 net/netlink/af_netlink.c:1339 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg+0x219/0x270 net/socket.c:727 ____sys_sendmsg+0x505/0x830 net/socket.c:2566 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620 __sys_sendmsg net/socket.c:2652 [inline] __do_sys_sendmsg net/socket.c:2657 [inline] __se_sys_sendmsg net/socket.c:2655 [inline] __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f5157b85d29 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:00007f51588dd038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f5157d75fa0 RCX: 00007f5157b85d29 RDX: 0000000000000000 RSI: 00000000200007c0 RDI: 0000000000000004 RBP: 00007f5157c01b08 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f5157d75fa0 R15: 00007ffc602a93c8 rcu: rcu_preempt kthread starved for 10496 jiffies! g15913 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:26872 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x16e2/0x4cd0 kernel/sched/core.c:6767 __schedule_loop kernel/sched/core.c:6845 [inline] schedule+0x165/0x360 kernel/sched/core.c:6860 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2046 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2248 kthread+0x70e/0x8a0 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 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: 6588 Comm: dhcpcd-run-hook Not tainted 6.15.0-rc5-syzkaller-01021-g0b28182c73a3 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:csd_lock_wait kernel/smp.c:340 [inline] RIP: 0010:smp_call_function_many_cond+0xe69/0x11c0 kernel/smp.c:885 Code: 00 45 8b 2f 44 89 ee 83 e6 01 31 ff e8 20 6d 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 cb 68 0b 00 eb 37 f3 90 <43> 0f b6 04 2c 84 c0 75 10 41 f7 07 01 00 00 00 74 1e e8 b0 68 0b RSP: 0018:ffffc900032af700 EFLAGS: 00000293 RAX: ffffffff81b467a0 RBX: ffff8880b893ad40 RCX: ffff8880243b9e00 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc900032af860 R08: ffffffff8f7f2d77 R09: 1ffffffff1efe5ae R10: dffffc0000000000 R11: fffffbfff1efe5af R12: 1ffff11017108245 R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8880b8841228 FS: 0000000000000000(0000) GS:ffff8881261c0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f682508c7d0 CR3: 0000000062db4000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1052 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1275 [inline] flush_tlb_mm_range+0x6ae/0x12b0 arch/x86/mm/tlb.c:1365 tlb_flush arch/x86/include/asm/tlb.h:23 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:480 [inline] tlb_flush_mmu+0x1a7/0x680 mm/mmu_gather.c:403 tlb_finish_mmu+0xc3/0x1d0 mm/mmu_gather.c:496 exit_mmap+0x474/0xba0 mm/mmap.c:1297 __mmput+0x118/0x420 kernel/fork.c:1379 exit_mm+0x1da/0x2c0 kernel/exit.c:589 do_exit+0x859/0x2550 kernel/exit.c:940 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+0x21ba/0x21c0 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f6824f8a6c5 Code: Unable to access opcode bytes at 0x7f6824f8a69b. RSP: 002b:00007ffc3f20cb78 EFLAGS: 00000202 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007ffc3f20ce04 RCX: 00007f6824f8a6c5 RDX: 00000000000000e7 RSI: ffffffffffffff88 RDI: 0000000000000000 RBP: 0000000000000003 R08: 00007ffc3f20cc70 R09: 0000000000000002 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 00007ffc3f20ceb0 R14: 00007f682519a000 R15: 00005568de2c0d98