rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-....: (9314 ticks this GP) idle=b444/1/0x4000000000000000 softirq=37073/37073 fqs=4584 rcu: hardirqs softirqs csw/system rcu: number: 4 6318 0 rcu: cputime: 0 1188 39453 ==> 52500(ms) rcu: (detected by 0, t=10502 jiffies, g=25141, q=455832 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 21 Comm: migration/1 Not tainted 6.15.0-rc6-syzkaller-00177-g882826f58b2c #0 PREEMPT(voluntary) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Stopper: 0x0 <- 0x0 RIP: 0010:io_serial_in+0x87/0xb0 drivers/tty/serial/8250/8250_port.c:410 Code: c3 ad fe 48 8d 7d 40 44 89 e1 48 b8 00 00 00 00 00 fc ff df 48 89 fa d3 e3 48 c1 ea 03 80 3c 02 00 75 1a 66 03 5d 40 89 da ec <5b> 0f b6 c0 5d 41 5c c3 cc cc cc cc e8 28 88 09 ff eb a2 e8 b1 88 RSP: 0018:ffffc900001a8498 EFLAGS: 00000002 RAX: dffffc0000000060 RBX: 00000000000003fd RCX: 0000000000000000 RDX: 00000000000003fd RSI: ffffffff82cea820 RDI: ffffffff938c7800 RBP: ffffffff938c77c0 R08: 0000000000000001 R09: 000000000000001f R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000020 R14: fffffbfff2718f52 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8882692c2000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fb1afb74fe0 CR3: 0000000008ea4000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: serial_in drivers/tty/serial/8250/8250.h:137 [inline] serial_lsr_in drivers/tty/serial/8250/8250.h:159 [inline] wait_for_lsr+0x137/0x210 drivers/tty/serial/8250/8250_port.c:2098 fifo_wait_for_lsr drivers/tty/serial/8250/8250_port.c:3348 [inline] serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3371 [inline] serial8250_console_write+0xf83/0x1890 drivers/tty/serial/8250/8250_port.c:3456 console_emit_next_record kernel/printk/printk.c:3138 [inline] console_flush_all+0x7fe/0xc60 kernel/printk/printk.c:3226 __console_flush_and_unlock kernel/printk/printk.c:3285 [inline] console_unlock+0xd8/0x210 kernel/printk/printk.c:3325 vprintk_emit+0x418/0x6d0 kernel/printk/printk.c:2450 dev_vprintk_emit drivers/base/core.c:4917 [inline] dev_printk_emit+0xfa/0x140 drivers/base/core.c:4928 __dev_printk+0xf5/0x270 drivers/base/core.c:4940 _dev_err+0xe4/0x120 drivers/base/core.c:4983 urb_irq_callback+0x454/0x700 drivers/input/misc/yealink.c:418 __usb_hcd_giveback_urb+0x38a/0x6e0 drivers/usb/core/hcd.c:1650 usb_hcd_giveback_urb+0x39b/0x450 drivers/usb/core/hcd.c:1734 dummy_timer+0x180e/0x3a20 drivers/usb/gadget/udc/dummy_hcd.c:1994 __run_hrtimer kernel/time/hrtimer.c:1761 [inline] __hrtimer_run_queues+0x1ff/0xad0 kernel/time/hrtimer.c:1825 hrtimer_run_softirq+0x17d/0x350 kernel/time/hrtimer.c:1842 handle_softirqs+0x205/0x8d0 kernel/softirq.c:579 __do_softirq kernel/softirq.c:613 [inline] invoke_softirq kernel/softirq.c:453 [inline] __irq_exit_rcu+0xfa/0x160 kernel/softirq.c:680 irq_exit_rcu+0x9/0x30 kernel/softirq.c:696 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0x90/0xb0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:finish_task_switch.isra.0+0x1e9/0x9e0 kernel/sched/core.c:5250 Code: 0f 85 5f 07 00 00 8b 0d 19 c4 2a 09 85 c9 0f 85 b9 02 00 00 48 89 df e8 f5 a3 d8 05 e8 e0 0e 36 00 fb 65 48 8b 1d bf cb 17 0b <48> 8d bb 50 15 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 RSP: 0018:ffffc9000016fc68 EFLAGS: 00000202 RAX: 0000000000000473 RBX: ffff888101ed1d40 RCX: ffffffff8184222f RDX: 0000000000000000 RSI: ffffffff88ad7713 RDI: ffffffff876851e0 RBP: ffffc9000016fca8 R08: 0000000000000001 R09: 0000000000000001 R10: ffffffff8a78cc97 R11: 0000000000000000 R12: ffff888104ecba80 R13: 0000000000000000 R14: ffff8881f5938418 R15: ffff8881f5938f18 context_switch kernel/sched/core.c:5385 [inline] __schedule+0x1332/0x3b00 kernel/sched/core.c:6767 __schedule_loop kernel/sched/core.c:6845 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6860 smpboot_thread_fn+0x8e6/0xae0 kernel/smpboot.c:160 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: rcu_preempt kthread starved for 1168 jiffies! g25141 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 yealink 5-1:36.0: unexpected response 0 rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. yealink 5-1:36.0: urb_ctl_callback - urb status -71 rcu: RCU grace-period kthread stack dump: task:rcu_preempt state:R yealink 5-1:36.0: urb_irq_callback - urb status -71 running task stack:27720 pid:15 tgid:15 ppid:2 task_flags:0x208040 flags:0x00004000 yealink 5-1:36.0: unexpected response 0 Call Trace: yealink 5-1:36.0: urb_ctl_callback - urb status -71 context_switch kernel/sched/core.c:5382 [inline] __schedule+0x132a/0x3b00 kernel/sched/core.c:6767 yealink 5-1:36.0: urb_irq_callback - urb status -71 yealink 5-1:36.0: unexpected response 0 yealink 5-1:36.0: urb_ctl_callback - urb status -71 yealink 5-1:36.0: urb_irq_callback - urb status -71 __schedule_loop kernel/sched/core.c:6845 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6860 yealink 5-1:36.0: unexpected response 0 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 yealink 5-1:36.0: urb_ctl_callback - urb status -71 yealink 5-1:36.0: urb_irq_callback - urb status -71 yealink 5-1:36.0: unexpected response 0 yealink 5-1:36.0: urb_ctl_callback - urb status -71 yealink 5-1:36.0: urb_irq_callback - urb status -71 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2046 yealink 5-1:36.0: unexpected response 0 yealink 5-1:36.0: urb_irq_callback - usb_submit_urb failed -19 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2248 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 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: 0 UID: 0 PID: 5400 Comm: udevd Not tainted 6.15.0-rc6-syzkaller-00177-g882826f58b2c #0 PREEMPT(voluntary) 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+0x4af/0x1290 kernel/smp.c:885 Code: 48 48 8b 44 24 20 49 89 c4 83 e0 07 49 c1 ec 03 48 89 c5 4d 01 f4 83 c5 03 e8 5d ea 0b 00 f3 90 41 0f b6 04 24 40 38 c5 7c 08 <84> c0 0f 85 de 0b 00 00 8b 43 08 31 ff 83 e0 01 41 89 c5 89 c6 e8 RSP: 0018:ffffc900124e77e0 EFLAGS: 00000206 RAX: 0000000000000000 RBX: ffff8881f593d780 RCX: ffffffff81708109 RDX: ffff88810c7f3a80 RSI: ffffffff817080e3 RDI: 0000000000000005 RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffffed103eb27af1 R13: 0000000000000001 R14: dffffc0000000000 R15: ffff8881f5839500 FS: 0000000000000000(0000) GS:ffff8882691c2000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f54685ef000 CR3: 000000015f614000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1052 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1291 [inline] flush_tlb_mm_range+0x322/0x1780 arch/x86/mm/tlb.c:1381 tlb_flush arch/x86/include/asm/tlb.h:23 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:480 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:470 [inline] tlb_flush_mmu mm/mmu_gather.c:403 [inline] tlb_finish_mmu+0x3c9/0x7b0 mm/mmu_gather.c:496 exit_mmap+0x403/0xb90 mm/mmap.c:1297 __mmput kernel/fork.c:1379 [inline] mmput+0xdb/0x430 kernel/fork.c:1401 exit_mm kernel/exit.c:589 [inline] do_exit+0x9d1/0x2c30 kernel/exit.c:940 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102 get_signal+0x2673/0x26d0 kernel/signal.c:3034 arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x147/0x260 kernel/entry/common.c:218 do_syscall_64+0xda/0x260 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f2ffbb70407 Code: Unable to access opcode bytes at 0x7f2ffbb703dd. RSP: 002b:00007ffc71f68f00 EFLAGS: 00000202 ORIG_RAX: 0000000000000000 RAX: fffffffffffffffc RBX: 00007f2ffba82880 RCX: 00007f2ffbb70407 RDX: 0000000000001000 RSI: 00007ffc71f693e0 RDI: 0000000000000008 RBP: 0000000000000008 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000556ebd09e500 R13: 00007ffc71f68fe0 R14: 00007ffc71f693e0 R15: 0000556eb5069bcc