==================================================================
BUG: KCSAN: data-race in batadv_hard_if_event / batadv_mcast_mla_update

write to 0xffff88815bc6f610 of 1 bytes by task 10150 on cpu 0:
 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]
 unregister_netdevice_queue+0x1fd/0x230 net/core/dev.c:11887
 unregister_netdevice include/linux/netdevice.h:3374 [inline]
 nsim_destroy+0x100/0x380 drivers/net/netdevsim/netdev.c:1064
 __nsim_dev_port_del+0xcd/0x100 drivers/net/netdevsim/dev.c:1428
 nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1440 [inline]
 nsim_dev_reload_destroy+0x1a6/0x2d0 drivers/net/netdevsim/dev.c:1661
 nsim_drv_remove+0x3e/0x100 drivers/net/netdevsim/dev.c:1676
 nsim_bus_remove+0x15/0x20 drivers/net/netdevsim/bus.c:398
 device_remove drivers/base/dd.c:567 [inline]
 __device_release_driver drivers/base/dd.c:1273 [inline]
 device_release_driver_internal+0x2e5/0x4f0 drivers/base/dd.c:1296
 device_release_driver+0x19/0x20 drivers/base/dd.c:1319
 bus_remove_device+0x26f/0x290 drivers/base/bus.c:579
 device_del+0x372/0x780 drivers/base/core.c:3855
 device_unregister+0x15/0x40 drivers/base/core.c:3896
 nsim_bus_dev_del drivers/net/netdevsim/bus.c:462 [inline]
 del_device_store+0x1dc/0x240 drivers/net/netdevsim/bus.c:226
 bus_attr_store+0x54/0x70 drivers/base/bus.c:172
 sysfs_kf_write+0xf3/0x110 fs/sysfs/file.c:145
 kernfs_fop_write_iter+0x1cd/0x2d0 fs/kernfs/file.c:334
 new_sync_write fs/read_write.c:591 [inline]
 vfs_write+0x79b/0x950 fs/read_write.c:684
 ksys_write+0xeb/0x1b0 fs/read_write.c:736
 __do_sys_write fs/read_write.c:747 [inline]
 __se_sys_write fs/read_write.c:744 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:744
 x64_sys_call+0x2a45/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88815bc6f610 of 1 bytes by task 109 on cpu 1:
 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: 1 UID: 0 PID: 109 Comm: kworker/u8:4 Not tainted 6.15.0-rc2-syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: bat_events batadv_mcast_mla_update
==================================================================
bridge0: port 1(bridge_slave_0) entered blocking state
bridge0: port 1(bridge_slave_0) entered forwarding state
GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog
IPVS: Schedule: port zero only supported in persistent services, check your ipvs configuration