rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=ca6c/1/0x4000000000000000 softirq=89254/89254 fqs=2 rcu: (detected by 0, t=10506 jiffies, g=84497, q=405 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 15364 Comm: syz.0.2514 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x70 kernel/kcov.c:210 Code: e6 b1 5e 00 48 89 df 5b e9 6d 52 64 00 be 03 00 00 00 5b e9 d2 51 f5 02 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1e fa 65 8b 05 c5 3f 06 12 48 8b 34 24 65 48 8b 15 a1 3f 06 RSP: 0018:ffffc90000a08d70 EFLAGS: 00000046 RAX: 0000000080010002 RBX: 0000000000000000 RCX: ffffffff89a35fad RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88803710a540 RBP: ffff88806beb4000 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000000 R11: ffffc90000a08ff8 R12: 0000000000000000 R13: ffff888032cdfc00 R14: ffff888032cdfc00 R15: ffff888032cdfc00 FS: 00007f8d259a66c0(0000) GS:ffff888124425000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000006680 CR3: 000000007bac4000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 00000000fda3b69a DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: taprio_set_budgets+0x251/0x310 net/sched/sch_taprio.c:680 advance_sched+0x66e/0xd20 net/sched/sch_taprio.c:984 __run_hrtimer kernel/time/hrtimer.c:2032 [inline] __hrtimer_run_queues+0x462/0x9c0 kernel/time/hrtimer.c:2096 hrtimer_interrupt+0x3e5/0x940 kernel/time/hrtimer.c:2215 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline] __sysvec_apic_timer_interrupt+0x109/0x470 arch/x86/kernel/apic/apic.c:1068 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0x9e/0xc0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:percpu_down_read_internal include/linux/percpu-rwsem.h:64 [inline] RIP: 0010:percpu_down_read include/linux/percpu-rwsem.h:77 [inline] RIP: 0010:cpus_read_lock+0x6c/0x170 kernel/cpu.c:490 Code: bf 01 00 00 00 e8 b4 50 0e 00 e8 af 0c cf 09 31 ff 89 c3 89 c6 e8 a4 f5 42 00 58 85 db 75 5d e8 ea fa 42 00 8b 1d 64 0b a1 0c <31> ff 89 de e8 8b f5 42 00 85 db 0f 85 bd 00 00 00 e8 ce fa 42 00 RSP: 0018:ffffc900078f7c90 EFLAGS: 00000287 RAX: 00000000000000d2 RBX: 0000000000000000 RCX: ffffc900068ab000 RDX: 0000000000080000 RSI: ffffffff81c67576 RDI: ffff88803710a540 RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000000 R11: ffffffffffffffff R12: 1ffff92000f1efb6 R13: 1ffff92000f1ef9f R14: 000000000d004021 R15: 0000000000000000 class_cpus_read_lock_constructor include/linux/cpuhplock.h:49 [inline] clock_was_set+0x96/0x850 kernel/time/hrtimer.c:988 do_settimeofday64+0x330/0x4d0 kernel/time/timekeeping.c:1684 do_sys_settimeofday64+0x1dc/0x260 kernel/time/time.c:195 __do_sys_clock_settime kernel/time/posix-timers.c:1139 [inline] __se_sys_clock_settime kernel/time/posix-timers.c:1123 [inline] __x64_sys_clock_settime+0x1c1/0x2a0 kernel/time/posix-timers.c:1123 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f8d24b9ce59 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:00007f8d259a6028 EFLAGS: 00000246 ORIG_RAX: 00000000000000e3 RAX: ffffffffffffffda RBX: 00007f8d24e15fa0 RCX: 00007f8d24b9ce59 RDX: 0000000000000000 RSI: 0000200000000240 RDI: 0000000000000000 RBP: 00007f8d24c32e6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f8d24e16038 R14: 00007f8d24e15fa0 R15: 00007ffeed8c1728 rcu: rcu_preempt kthread starved for 10495 jiffies! g84497 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:29168 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5504 [inline] __schedule+0x125c/0x6730 kernel/sched/core.c:7228 __schedule_loop kernel/sched/core.c:7307 [inline] schedule+0xdd/0x390 kernel/sched/core.c:7322 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2123 rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2325 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 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: CPU: 0 UID: 0 PID: 15357 Comm: syz.1.2511 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0x589/0x16c0 kernel/smp.c:892 Code: b8 00 00 00 00 00 fc ff df 48 8b 54 24 08 49 89 d5 49 89 d4 49 c1 ed 03 41 83 e4 07 49 01 c5 41 83 c4 03 e8 39 93 0c 00 f3 90 <41> 0f b6 45 00 41 38 c4 7c 08 84 c0 0f 85 2c 0f 00 00 8b 45 08 31 RSP: 0018:ffffc90003fb7650 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff81fcdd4d RDX: ffff888036f94a80 RSI: ffffffff81fcdd27 RDI: ffff888036f94a80 RBP: ffff8880b8541080 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000003 R13: ffffed10170a8211 R14: 0000000000000001 R15: ffff8880b843c700 FS: 0000000000000000(0000) GS:ffff888124325000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fef36846e9c CR3: 0000000067498000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1057 __flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline] flush_tlb_mm_range+0x45f/0x16f0 arch/x86/mm/tlb.c:1451 tlb_flush arch/x86/include/asm/tlb.h:23 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:509 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:499 [inline] tlb_flush_mmu mm/mmu_gather.c:423 [inline] tlb_finish_mmu+0x3fe/0x810 mm/mmu_gather.c:549 exit_mmap+0x454/0xa00 mm/mmap.c:1313 __mmput+0x12a/0x410 kernel/fork.c:1181 mmput+0x67/0x80 kernel/fork.c:1204 exit_mm kernel/exit.c:610 [inline] do_exit+0x8b1/0x2ae0 kernel/exit.c:992 do_group_exit+0xd5/0x2a0 kernel/exit.c:1147 get_signal+0x1ec7/0x21e0 kernel/signal.c:3038 arch_do_signal_or_restart+0x91/0x7e0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline] exit_to_user_mode_loop+0x139/0x6f0 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:318 [inline] do_syscall_64+0x666/0x870 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f5562b9ce59 Code: Unable to access opcode bytes at 0x7f5562b9ce2f. RSP: 002b:00007f55639ce028 EFLAGS: 00000246 ORIG_RAX: 0000000000000029 RAX: 00000000000000ac RBX: 00007f5562e16180 RCX: 00007f5562b9ce59 RDX: 000000000000000c RSI: 0000000000000003 RDI: 0000000000000010 RBP: 00007f5562c32e6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f5562e16218 R14: 00007f5562e16180 R15: 00007ffef117ecd8