syzbot

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-....: (1 GPs behind) idle=21e/1/0x4000000000000000 softirq=59805/59806 fqs=115 
	(t=10501 jiffies g=80069 q=2054)
rcu: rcu_preempt kthread starved for 320 jiffies! g80069 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:28888 pid:   13 ppid:     2 flags:0x00004000
Call Trace:
 context_switch kernel/sched/core.c:4327 [inline]
 __schedule+0x90c/0x21a0 kernel/sched/core.c:5078
 schedule+0xcf/0x270 kernel/sched/core.c:5157
 schedule_timeout+0x148/0x250 kernel/time/timer.c:1878
 rcu_gp_fqs_loop kernel/rcu/tree.c:1940 [inline]
 rcu_gp_kthread+0xbbe/0x1d70 kernel/rcu/tree.c:2113
 kthread+0x3b1/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
NMI backtrace for cpu 1
CPU: 1 PID: 20276 Comm: syz-executor.3 Not tainted 5.11.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:120
 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105
 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x1f4/0x230 kernel/rcu/tree_stall.h:337
 print_cpu_stall kernel/rcu/tree_stall.h:569 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:643 [inline]
 rcu_pending kernel/rcu/tree.c:3751 [inline]
 rcu_sched_clock_irq.cold+0x48e/0xedf kernel/rcu/tree.c:2580
 update_process_times+0x16d/0x200 kernel/time/timer.c:1782
 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226
 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1369
 __run_hrtimer kernel/time/hrtimer.c:1519 [inline]
 __hrtimer_run_queues+0x1c0/0xe40 kernel/time/hrtimer.c:1583
 hrtimer_interrupt+0x334/0x940 kernel/time/hrtimer.c:1645
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1089 [inline]
 __sysvec_apic_timer_interrupt+0x146/0x540 arch/x86/kernel/apic/apic.c:1106
 run_sysvec_on_irqstack_cond arch/x86/include/asm/irq_stack.h:91 [inline]
 sysvec_apic_timer_interrupt+0x48/0x100 arch/x86/kernel/apic/apic.c:1100
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:629
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x25/0x50 kernel/locking/spinlock.c:191
Code: f8 5d c3 66 90 55 48 89 fd 48 83 c7 18 53 48 89 f3 48 8b 74 24 10 e8 aa c6 5b f8 48 89 ef e8 52 7b 5c f8 f6 c7 02 75 1a 53 9d <bf> 01 00 00 00 e8 91 82 50 f8 65 8b 05 8a e8 04 77 85 c0 74 0a 5b
RSP: 0000:ffffc90000db0bd0 EFLAGS: 00000216
RAX: 0000000000d2d346 RBX: 0000000000000216 RCX: ffffffff81585217
RDX: 0000000000000000 RSI: 0000000000000102 RDI: 0000000000000000
RBP: ffffffff8fdc4488 R08: 0000000000000001 R09: ffffffff8f8668cf
R10: fffffbfff1f0cd19 R11: 000000000000003f R12: 000000000000000a
R13: 000000000000000a R14: dead000000000100 R15: dffffc0000000000
 __debug_check_no_obj_freed lib/debugobjects.c:997 [inline]
 debug_check_no_obj_freed+0x20c/0x420 lib/debugobjects.c:1018
 slab_free_hook mm/slub.c:1539 [inline]
 slab_free_freelist_hook+0x107/0x150 mm/slub.c:1580
 slab_free mm/slub.c:3143 [inline]
 kmem_cache_free+0x82/0x350 mm/slub.c:3159
 inet_twsk_free+0x123/0x180 net/ipv4/inet_timewait_sock.c:73
 inet_twsk_put+0x78/0xa0 net/ipv4/inet_timewait_sock.c:80
 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1417
 expire_timers kernel/time/timer.c:1462 [inline]
 __run_timers.part.0+0x67c/0xa50 kernel/time/timer.c:1731
 __run_timers kernel/time/timer.c:1712 [inline]
 run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1744
 __do_softirq+0x29b/0x9f6 kernel/softirq.c:343
 asm_call_irq_on_stack+0xf/0x20
 </IRQ>
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline]
 do_softirq_own_stack+0xaa/0xd0 arch/x86/kernel/irq_64.c:77
 invoke_softirq kernel/softirq.c:226 [inline]
 __irq_exit_rcu kernel/softirq.c:420 [inline]
 irq_exit_rcu+0x134/0x200 kernel/softirq.c:432
 sysvec_apic_timer_interrupt+0x4d/0x100 arch/x86/kernel/apic/apic.c:1100
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:629
RIP: 0010:preempt_schedule_irq+0x49/0x90 kernel/sched/core.c:5340
Code: 55 53 65 48 8b 1c 25 00 f0 01 00 48 89 dd 48 c1 ed 03 48 01 c5 bf 01 00 00 00 e8 c2 72 51 f8 e8 4d 7e 7c f8 fb bf 01 00 00 00 <e8> 02 d1 ff ff 9c 58 fa f6 c4 02 75 27 bf 01 00 00 00 e8 d0 60 51
RSP: 0000:ffffc90016c7fe68 EFLAGS: 00000206
RAX: 000000000002c3a9 RBX: ffff88801f9c9bc0 RCX: 1ffffffff1b46ad9
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001
RBP: ffffed1003f39378 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff8178a758 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 irqentry_exit_cond_resched kernel/entry/common.c:385 [inline]
 irqentry_exit_cond_resched kernel/entry/common.c:377 [inline]
 irqentry_exit+0x7a/0xa0 kernel/entry/common.c:415
 asm_sysvec_irq_work+0x12/0x20 arch/x86/include/asm/idtentry.h:655
RIP: 0010:exit_to_user_mode_loop kernel/entry/common.c:161 [inline]
RIP: 0010:exit_to_user_mode_prepare+0x10e/0x250 kernel/entry/common.c:201
Code: f6 c4 02 0f 85 0f 01 00 00 65 48 8b 04 25 00 f0 01 00 48 8b 18 f7 c3 0e 30 02 00 0f 84 2f ff ff ff e8 56 6a 17 00 fb f6 c3 08 <74> bf e8 ab de 9a 07 f6 c7 10 74 ba 48 89 ef e8 ce ca 32 00 f7 c3
RSP: 0000:ffffc90016c7ff30 EFLAGS: 00000202
RAX: 000000000002c3a7 RBX: 0000000000000008 RCX: 1ffffffff1b46ad9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90016c7ff58 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff8178a758 R11: 0000000000000001 R12: ffff88801f9c9bc0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 irqentry_exit_to_user_mode+0x5/0x30 kernel/entry/common.c:307
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:629
RIP: 0033:0x465b09
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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0c17e2e188 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 000000000056bf60 RCX: 0000000000465b09
RDX: 0000000000042000 RSI: 0000000000000004 RDI: 0000000000000003
RBP: 00000000004b069f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffc67ed432f R14: 00007f0c17e2e300 R15: 0000000000022000