syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
	(detected by 1, t=10502 jiffies, g=59585, q=815)
rcu: All QSes seen, last rcu_preempt kthread activity 10463 (4294992605-4294982142), jiffies_till_next_fqs=1, root ->qsmask 0x0
syz-executor.0  R  running task    27960 16367   8721 0x00000000
Call Trace:
 <IRQ>
 sched_show_task+0x411/0x560 kernel/sched/core.c:5952
 print_other_cpu_stall kernel/rcu/tree_stall.h:430 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:558 [inline]
 rcu_pending kernel/rcu/tree.c:3030 [inline]
 rcu_sched_clock_irq+0x188c/0x1aa0 kernel/rcu/tree.c:2276
 update_process_times+0x12d/0x180 kernel/time/timer.c:1726
 tick_sched_handle kernel/time/tick-sched.c:171 [inline]
 tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1314
 __run_hrtimer kernel/time/hrtimer.c:1517 [inline]
 __hrtimer_run_queues+0x3f3/0x840 kernel/time/hrtimer.c:1579
 hrtimer_interrupt+0x37c/0xda0 kernel/time/hrtimer.c:1641
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1119 [inline]
 smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1144
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:752 [inline]
RIP: 0010:lock_acquire+0x1ae/0x250 kernel/locking/lockdep.c:4487
Code: c1 e8 03 42 80 3c 30 00 74 0c 48 c7 c7 10 d3 2a 89 e8 56 67 58 00 48 83 3d 6e 07 cf 07 00 0f 84 9c 00 00 00 48 8b 7d c0 57 9d <0f> 1f 44 00 00 48 83 c4 30 5b 41 5c 41 5d 41 5e 41 5f 5d c3 44 89
RSP: 0000:ffffc90002e47db0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff1255a62 RBX: 0000000000000000 RCX: 2f6a86943080f3c2
RDX: dffffc0000000000 RSI: ffff888051310ad8 RDI: 0000000000000282
RBP: ffffc90002e47e08 R08: dffffc0000000000 R09: fffffbfff140651b
R10: fffffbfff140651b R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000000001 R14: dffffc0000000000 R15: ffff88803eced598
 down_read_trylock+0x1ae/0x300 kernel/locking/rwsem.c:1523
 do_user_addr_fault+0x382/0xaf0 arch/x86/mm/fault.c:1383
 do_page_fault+0x13b/0x250 arch/x86/mm/fault.c:1517
 page_fault+0x39/0x40 arch/x86/entry/entry_64.S:1203
RIP: 0033:0x405899
Code: d0 ff ff ff 01 48 8b 7c 24 28 c7 44 24 34 00 00 00 00 e8 ca ed 01 00 85 c0 75 23 48 6b 44 24 20 18 8b 7c 24 1c 48 03 44 24 38 <48> 8b 48 10 48 8b 50 08 48 8b 30 e8 67 09 01 00 89 44 24 34 64 f0
RSP: 002b:00007f13b5baba70 EFLAGS: 00010202
RAX: 0000000025d72438 RBX: 00007f13b5bac6d4 RCX: 0000000000416247
RDX: 8f1e36020de31e6a RSI: 0000000000000000 RDI: 0000000000000004
RBP: 000000000076bf20 R08: 00007f13b5baba70 R09: 000000000076bf20
R10: 0000000000000000 R11: 0000000000000000 R12: 00000000ffffffff
R13: 0000000000000be8 R14: 00000000004cdca6 R15: 000000000076bf2c
rcu: rcu_preempt kthread starved for 10488 jiffies! g59585 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    28984    10      2 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:3380 [inline]
 __schedule+0x87f/0xcd0 kernel/sched/core.c:4080
 schedule+0x188/0x210 kernel/sched/core.c:4154
 schedule_timeout+0x14f/0x240 kernel/time/timer.c:1895
 rcu_gp_fqs_loop kernel/rcu/tree.c:1658 [inline]
 rcu_gp_kthread+0xe8d/0x17e0 kernel/rcu/tree.c:1818
 kthread+0x332/0x350 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352