syzbot

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BUG: KCSAN: data-race in expire_timers / try_to_del_timer_sync

write to 0xffff88813bd1bc48 of 8 bytes by interrupt on cpu 1:
 expire_timers+0x164/0x260 kernel/time/timer.c:1451
 __run_timers+0x328/0x3c0 kernel/time/timer.c:1747
 run_timer_softirq+0x19/0x30 kernel/time/timer.c:1760
 __do_softirq+0x12c/0x2b1 kernel/softirq.c:298
 asm_call_irq_on_stack+0xf/0x20
 __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+0x32/0x40 arch/x86/kernel/irq_64.c:77
 do_softirq kernel/softirq.c:343 [inline]
 __local_bh_enable_ip+0xba/0xd0 kernel/softirq.c:195
 local_bh_enable+0x1b/0x20 include/linux/bottom_half.h:32
 get_next_corpse net/netfilter/nf_conntrack_core.c:2221 [inline]
 nf_ct_iterate_cleanup+0x2c2/0x360 net/netfilter/nf_conntrack_core.c:2244
 nf_ct_iterate_cleanup_net+0x77/0xb0 net/netfilter/nf_conntrack_core.c:2329
 masq_device_event+0x6b/0x80 net/netfilter/nf_nat_masquerade.c:88
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0x53/0xb0 kernel/notifier.c:410
 call_netdevice_notifiers_info net/core/dev.c:2035 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2047 [inline]
 call_netdevice_notifiers net/core/dev.c:2061 [inline]
 dev_close_many+0x202/0x310 net/core/dev.c:1636
 rollback_registered_many+0x252/0xe40 net/core/dev.c:9399
 unregister_netdevice_many net/core/dev.c:10626 [inline]
 default_device_exit_batch+0x250/0x3d0 net/core/dev.c:11109
 ops_exit_list net/core/net_namespace.c:190 [inline]
 cleanup_net+0x4cc/0x8a0 net/core/net_namespace.c:604
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2272
 worker_thread+0x635/0xb90 kernel/workqueue.c:2418
 kthread+0x1fa/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffff88813bd1bc48 of 8 bytes by task 11 on cpu 0:
 try_to_del_timer_sync+0xe3/0x2c0 kernel/time/timer.c:1231
 del_timer_sync kernel/time/timer.c:1371 [inline]
 schedule_timeout+0x108/0x280 kernel/time/timer.c:1872
 rcu_gp_fqs_loop kernel/rcu/tree.c:1925 [inline]
 rcu_gp_kthread+0x98d/0x1320 kernel/rcu/tree.c:2099
 kthread+0x1fa/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 11 Comm: rcu_preempt Not tainted 5.10.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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