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BUG: KCSAN: data-race in enqueue_timer / wbt_wait

read to 0xffff8880b110d618 of 8 bytes by task 18455 on cpu 0:
 blk_stat_is_active block/blk-stat.h:131 [inline]
 wbt_wait+0x177/0x250 block/blk-wbt.c:593
 __rq_qos_throttle+0x47/0x70 block/blk-rq-qos.c:72
 rq_qos_throttle block/blk-rq-qos.h:182 [inline]
 blk_mq_make_request+0x29c/0xf60 block/blk-mq.c:1971
 generic_make_request block/blk-core.c:1064 [inline]
 generic_make_request+0x196/0x740 block/blk-core.c:1006
 submit_bio+0x96/0x3c0 block/blk-core.c:1190
 submit_bh_wbc+0x40f/0x460 fs/buffer.c:3095
 __block_write_full_page+0x4e9/0x870 fs/buffer.c:1767
 block_write_full_page+0x1c0/0x1e0 fs/buffer.c:2953
 blkdev_writepage+0x2e/0x40 fs/block_dev.c:609
 __writepage+0x40/0xb0 mm/page-writeback.c:2303
 write_cache_pages+0x47a/0xb40 mm/page-writeback.c:2238
 generic_writepages mm/page-writeback.c:2329 [inline]
 generic_writepages+0x79/0xc0 mm/page-writeback.c:2318
 blkdev_writepages+0x27/0x40 fs/block_dev.c:2031
 do_writepages+0x6b/0x170 mm/page-writeback.c:2344
 __writeback_single_inode+0xaf/0x8e0 fs/fs-writeback.c:1449
 writeback_sb_inodes+0x4ba/0xa50 fs/fs-writeback.c:1713
 __writeback_inodes_wb+0xe8/0x1b0 fs/fs-writeback.c:1782
 wb_writeback+0x557/0x6a0 fs/fs-writeback.c:1891
 wb_check_old_data_flush fs/fs-writeback.c:1993 [inline]
 wb_do_writeback fs/fs-writeback.c:2046 [inline]
 wb_workfn+0x7bb/0x970 fs/fs-writeback.c:2075
 process_one_work+0x3d4/0x890 kernel/workqueue.c:2269
 worker_thread+0xa0/0x800 kernel/workqueue.c:2415
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

write to 0xffff8880b110d618 of 8 bytes by interrupt on cpu 1:
 hlist_add_head include/linux/list.h:787 [inline]
 enqueue_timer+0x6c/0x210 kernel/time/timer.c:540
 __internal_add_timer+0x4f/0x60 kernel/time/timer.c:553
 internal_add_timer kernel/time/timer.c:595 [inline]
 __mod_timer kernel/time/timer.c:1053 [inline]
 mod_timer kernel/time/timer.c:1100 [inline]
 add_timer+0x250/0x550 kernel/time/timer.c:1136
 dsp_cmx_send+0x8cd/0xcf0 drivers/isdn/mISDN/dsp_cmx.c:1850
 call_timer_fn+0x5f/0x2f0 kernel/time/timer.c:1404
 expire_timers kernel/time/timer.c:1449 [inline]
 __run_timers kernel/time/timer.c:1773 [inline]
 __run_timers kernel/time/timer.c:1740 [inline]
 run_timer_softirq+0xc0c/0xcd0 kernel/time/timer.c:1786
 __do_softirq+0x115/0x33f kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0xbb/0xe0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:536 [inline]
 smp_apic_timer_interrupt+0xe6/0x280 arch/x86/kernel/apic/apic.c:1137
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
 __tsan_func_entry+0x0/0x10 kernel/kcsan/core.c:487
 __local_bh_enable_ip+0x56/0x80 kernel/softirq.c:184
 local_bh_enable include/linux/bottom_half.h:32 [inline]
 get_next_corpse net/netfilter/nf_conntrack_core.c:2013 [inline]
 nf_ct_iterate_cleanup+0x129/0x2e0 net/netfilter/nf_conntrack_core.c:2036
 nf_ct_iterate_cleanup_net net/netfilter/nf_conntrack_core.c:2121 [inline]
 nf_ct_iterate_cleanup_net+0xe2/0xf0 net/netfilter/nf_conntrack_core.c:2106
 masq_device_event+0x8a/0x90 net/netfilter/nf_nat_masquerade.c:88
 notifier_call_chain+0xd7/0x160 kernel/notifier.c:95
 __raw_notifier_call_chain kernel/notifier.c:396 [inline]
 raw_notifier_call_chain+0x37/0x50 kernel/notifier.c:403
 call_netdevice_notifiers_info+0x48/0xc0 net/core/dev.c:1668
 call_netdevice_notifiers_extack net/core/dev.c:1680 [inline]
 call_netdevice_notifiers net/core/dev.c:1694 [inline]
 dev_close_many+0x264/0x3a0 net/core/dev.c:1437
 rollback_registered_many+0x2fb/0xa00 net/core/dev.c:8499
 unregister_netdevice_many net/core/dev.c:9675 [inline]
 unregister_netdevice_many+0x62/0x240 net/core/dev.c:9670
 default_device_exit_batch+0x234/0x270 net/core/dev.c:10146
 ops_exit_list.isra.0+0xa2/0xc0 net/core/net_namespace.c:175
 cleanup_net+0x405/0x6b0 net/core/net_namespace.c:597
 process_one_work+0x3d4/0x890 kernel/workqueue.c:2269
 worker_thread+0xa0/0x800 kernel/workqueue.c:2415
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 18377 Comm: kworker/u4:8 Not tainted 5.4.0-rc6+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
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