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BUG: KCSAN: data-race in enqueue_timer / sctp_addr_wq_mgmt

read to 0xffff88810a30f058 of 8 bytes by task 17192 on cpu 0:
 sctp_addr_wq_mgmt+0x2ae/0x410 net/sctp/protocol.c:740
 sctp_inet6addr_event+0x3e0/0x440 net/sctp/ipv6.c:93
 notifier_call_chain+0xd7/0x160 kernel/notifier.c:83
 __atomic_notifier_call_chain kernel/notifier.c:173 [inline]
 atomic_notifier_call_chain+0x3c/0x60 kernel/notifier.c:183
 inet6addr_notifier_call_chain+0x2e/0x40 net/ipv6/addrconf_core.c:109
 ipv6_add_addr+0xccf/0xf40 net/ipv6/addrconf.c:1150
 addrconf_add_linklocal+0x15f/0x2a0 net/ipv6/addrconf.c:3190
 addrconf_addr_gen+0x1ff/0x230 net/ipv6/addrconf.c:3317
 addrconf_dev_config+0x1c0/0x280 net/ipv6/addrconf.c:3360
 addrconf_notify+0x1fa/0x1550 net/ipv6/addrconf.c:3595
 notifier_call_chain+0xd7/0x160 kernel/notifier.c:83
 __raw_notifier_call_chain kernel/notifier.c:361 [inline]
 raw_notifier_call_chain+0x37/0x50 kernel/notifier.c:368
 call_netdevice_notifiers_info net/core/dev.c:1893 [inline]
 call_netdevice_notifiers_info+0x9a/0x120 net/core/dev.c:1878
 netdev_state_change net/core/dev.c:1378 [inline]
 netdev_state_change+0xb2/0xd0 net/core/dev.c:1371
 linkwatch_do_dev+0xd8/0xf0 net/core/link_watch.c:159
 __linkwatch_run_queue+0x1a9/0x510 net/core/link_watch.c:204
 linkwatch_event+0x54/0x70 net/core/link_watch.c:243
 process_one_work+0x3d4/0x890 kernel/workqueue.c:2264
 worker_thread+0xa0/0x800 kernel/workqueue.c:2410
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

write to 0xffff88810a30f058 of 8 bytes by task 98 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
 __queue_delayed_work+0x13b/0x1d0 kernel/workqueue.c:1644
 queue_delayed_work_on+0xf3/0x110 kernel/workqueue.c:1669
 queue_delayed_work include/linux/workqueue.h:509 [inline]
 batadv_nc_start_timer net/batman-adv/network-coding.c:79 [inline]
 batadv_nc_worker+0x29d/0x390 net/batman-adv/network-coding.c:740
 process_one_work+0x3d4/0x890 kernel/workqueue.c:2264
 worker_thread+0xa0/0x800 kernel/workqueue.c:2410
 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: 98 Comm: kworker/u4:2 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: bat_events batadv_nc_worker
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