syzbot

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-....: (10500 ticks this GP) idle=352/1/0x4000000000000002 softirq=288483/288492 fqs=5250 
rcu: 	 (t=10502 jiffies g=226445 q=6823)
NMI backtrace for cpu 1
CPU: 1 PID: 5380 Comm: syz-executor.1 Not tainted 5.1.0-rc1+ #32
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1be/0x236 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x183/0x1cf kernel/rcu/tree.c:1223
 print_cpu_stall kernel/rcu/tree.c:1360 [inline]
 check_cpu_stall kernel/rcu/tree.c:1434 [inline]
 rcu_pending kernel/rcu/tree.c:3103 [inline]
 rcu_sched_clock_irq.cold+0x500/0xa4a kernel/rcu/tree.c:2544
 update_process_times+0x32/0x80 kernel/time/timer.c:1635
 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:161
 tick_sched_timer+0x47/0x130 kernel/time/tick-sched.c:1271
 __run_hrtimer kernel/time/hrtimer.c:1389 [inline]
 __hrtimer_run_queues+0x33e/0xde0 kernel/time/hrtimer.c:1451
 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1509
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1035 [inline]
 smp_apic_timer_interrupt+0x120/0x570 arch/x86/kernel/apic/apic.c:1060
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807
 </IRQ>
RIP: 0010:kimage_alloc_page+0xf0/0x9f0 kernel/kexec_core.c:707
Code: 7d d0 4c 39 ff 0f 84 95 04 00 00 e8 5a 76 08 00 49 8d 7e 08 48 89 f8 48 c1 e8 03 42 80 3c 28 00 0f 85 bf 07 00 00 4d 8b 66 08 <4c> 3b 65 a8 4d 8d 74 24 f8 75 ac 49 bf 00 00 00 00 00 fc ff df 48
RSP: 0018:ffff88805a347d90 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 1ffffd40000909f9 RBX: 0000160000000000 RCX: ffffc90008076000
RDX: 0000000000040000 RSI: ffffffff8167f936 RDI: ffffea0000484fc8
RBP: ffff88805a347e08 R08: ffff88809b8d0080 R09: 0000000000000002
R10: ffff88809b8d0928 R11: ffff88809b8d0080 R12: ffffea0000484f88
R13: dffffc0000000000 R14: ffffea0000484fc0 R15: 00000000056d4000
 kimage_load_normal_segment kernel/kexec_core.c:802 [inline]
 kimage_load_segment+0x25d/0x740 kernel/kexec_core.c:919
 do_kexec_load+0x41a/0x600 kernel/kexec.c:157
 __do_sys_kexec_load kernel/kexec.c:251 [inline]
 __se_sys_kexec_load kernel/kexec.c:226 [inline]
 __x64_sys_kexec_load+0x1d5/0x260 kernel/kexec.c:226
 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458209
Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fb533c80c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000f6
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000458209
RDX: 00000000200006c0 RSI: 0000000000000010 RDI: 0000000000000000
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb533c816d4
R13: 00000000004c3b35 R14: 00000000004d6a18 R15: 00000000ffffffff