syzbot

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (1 GPs behind) idle=94f/1/0x4000000000000000 softirq=22182/22183 fqs=503 
	(t=10502 jiffies g=26061 q=157)
rcu: rcu_preempt kthread timer wakeup didn't happen for 9469 jiffies! g26061 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=19646
rcu: rcu_preempt kthread starved for 9472 jiffies! g26061 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27032 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5027 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6373
 schedule+0x11b/0x1f0 kernel/sched/core.c:6456
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x2bf/0x1080 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0xa4/0x360 kernel/rcu/tree.c:2145
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_safe_halt drivers/acpi/processor_idle.c:108 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:562
NMI backtrace for cpu 1
CPU: 1 PID: 7853 Comm: syz.9.607 Not tainted 5.15.173-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x46a/0x4a0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x181/0x2a0 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_dump_cpu_stacks+0x223/0x390 kernel/rcu/tree_stall.h:349
 print_cpu_stall+0x320/0x600 kernel/rcu/tree_stall.h:633
 check_cpu_stall kernel/rcu/tree_stall.h:727 [inline]
 rcu_pending kernel/rcu/tree.c:3932 [inline]
 rcu_sched_clock_irq+0x8d9/0x1150 kernel/rcu/tree.c:2619
 update_process_times+0x196/0x200 kernel/time/timer.c:1818
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x386/0x550 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1688 [inline]
 __hrtimer_run_queues+0x55b/0xcf0 kernel/time/hrtimer.c:1752
 hrtimer_interrupt+0x392/0x980 kernel/time/hrtimer.c:1814
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x13b/0x4b0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:check_kcov_mode kernel/kcov.c:172 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:227 [inline]
RIP: 0010:__sanitizer_cov_trace_switch+0x64/0xe0 kernel/kcov.c:329
Code: c5 00 ea 8e 8a 4c 8b 4c 24 20 65 4c 8b 1d 74 f7 81 7e 31 d2 eb 08 48 ff c2 49 39 d2 74 71 4c 8b 74 d6 10 65 8b 05 64 f7 81 7e <25> 00 01 ff 00 74 11 3d 00 01 00 00 75 de 41 83 bb 34 16 00 00 00
RSP: 0018:ffffc90003296f30 EFLAGS: 00000202
RAX: 0000000000000201 RBX: 0000000000000000 RCX: 000000000000008b
RDX: 0000000000000001 RSI: ffffffff8db21450 RDI: 0000000000000011
RBP: ffff8880786cbf88 R08: 0000000000000001 R09: ffffffff8901dfa1
R10: 0000000000000008 R11: ffff888074bd0000 R12: 0000000000000000
R13: ffff888077c808d8 R14: 0000000000000006 R15: dffffc0000000000
 xfrm_flowi_sport include/net/xfrm.h:846 [inline]
 __xfrm4_selector_match net/xfrm/xfrm_policy.c:205 [inline]
 xfrm_selector_match+0x761/0x1030 net/xfrm/xfrm_policy.c:228
 xfrm_sk_policy_lookup+0x221/0x800 net/xfrm/xfrm_policy.c:2195
 xfrm_lookup_with_ifid+0x23f/0x2420 net/xfrm/xfrm_policy.c:3078
 xfrm_lookup net/xfrm/xfrm_policy.c:3220 [inline]
 xfrm_lookup_route+0x38/0x1a0 net/xfrm/xfrm_policy.c:3231
 ip_route_output_ports include/net/route.h:169 [inline]
 __ip_queue_xmit+0x8d7/0x1d90 net/ipv4/ip_output.c:488
 l2tp_xmit_queue net/l2tp/l2tp_core.c:1012 [inline]
 l2tp_xmit_core net/l2tp/l2tp_core.c:1104 [inline]
 l2tp_xmit_skb+0xf9a/0x1750 net/l2tp/l2tp_core.c:1120
 pppol2tp_sendmsg+0x388/0x5f0 net/l2tp/l2tp_ppp.c:319
 sock_sendmsg_nosec net/socket.c:704 [inline]
 __sock_sendmsg net/socket.c:716 [inline]
 sock_sendmsg net/socket.c:739 [inline]
 kernel_sendmsg+0x205/0x2e0 net/socket.c:763
 sock_no_sendpage+0x156/0x1c0 net/core/sock.c:3036
 kernel_sendpage+0x25f/0x390 net/socket.c:3541
 sock_sendpage+0x7f/0xb0 net/socket.c:1025
 pipe_to_sendpage+0x260/0x350 fs/splice.c:364
 splice_from_pipe_feed fs/splice.c:418 [inline]
 __splice_from_pipe+0x33b/0x890 fs/splice.c:562
 splice_from_pipe fs/splice.c:597 [inline]
 generic_splice_sendpage+0x195/0x220 fs/splice.c:746
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0xe3/0x1c0 fs/splice.c:936
 splice_direct_to_actor+0x500/0xc10 fs/splice.c:891
 do_splice_direct+0x285/0x3d0 fs/splice.c:979
 do_sendfile+0x622/0x1000 fs/read_write.c:1249
 __do_sys_sendfile64 fs/read_write.c:1317 [inline]
 __se_sys_sendfile64+0x178/0x1e0 fs/read_write.c:1303
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f0658e68759
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:00007f06572e0038 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f065901ff80 RCX: 00007f0658e68759
RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000006
RBP: 00007f0658edb75e R08: 0000000000000000 R09: 0000000000000000
R10: 000080001d00c0d0 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f065901ff80 R15: 00007ffc029998a8
 </TASK>
vkms_vblank_simulate: vblank timer overrun