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BUG: KCSAN: data-race in batadv_hard_if_event / batadv_mcast_mla_update

write to 0xffff888114973210 of 1 bytes by task 3418 on cpu 1:
 batadv_hardif_remove_interface net/batman-adv/hard-interface.c:924 [inline]
 batadv_hard_if_event+0x838/0xf50 net/batman-adv/hard-interface.c:982
 notifier_call_chain kernel/notifier.c:85 [inline]
 raw_notifier_call_chain+0x6f/0x1d0 kernel/notifier.c:453
 call_netdevice_notifiers_info+0xae/0x100 net/core/dev.c:2174
 call_netdevice_notifiers_extack net/core/dev.c:2212 [inline]
 call_netdevice_notifiers net/core/dev.c:2226 [inline]
 unregister_netdevice_many_notify+0xd12/0x1600 net/core/dev.c:11971
 unregister_netdevice_many net/core/dev.c:12035 [inline]
 default_device_exit_batch+0x500/0x560 net/core/dev.c:12527
 ops_exit_list net/core/net_namespace.c:177 [inline]
 cleanup_net+0x4f0/0x8a0 net/core/net_namespace.c:654
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4de/0xa20 kernel/workqueue.c:3319
 worker_thread+0x52c/0x710 kernel/workqueue.c:3400
 kthread+0x4b7/0x540 kernel/kthread.c:464
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff888114973210 of 1 bytes by task 51 on cpu 0:
 batadv_mcast_mla_forw_flags_get net/batman-adv/multicast.c:252 [inline]
 batadv_mcast_mla_flags_get net/batman-adv/multicast.c:289 [inline]
 __batadv_mcast_mla_update net/batman-adv/multicast.c:909 [inline]
 batadv_mcast_mla_update+0x21d/0x1710 net/batman-adv/multicast.c:948
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4de/0xa20 kernel/workqueue.c:3319
 worker_thread+0x52c/0x710 kernel/workqueue.c:3400
 kthread+0x4b7/0x540 kernel/kthread.c:464
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 51 Comm: kworker/u8:3 Not tainted 6.15.0-rc1-syzkaller-00325-g7cdabafc0012 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: bat_events batadv_mcast_mla_update
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