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BUG: KCSAN: data-race in batadv_hard_if_event / batadv_mcast_mla_update

write to 0xffff88811889c810 of 1 bytes by task 8671 on cpu 1:
 batadv_hardif_remove_interface net/batman-adv/hard-interface.c:930 [inline]
 batadv_hard_if_event+0x896/0xfb0 net/batman-adv/hard-interface.c:988
 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:2206
 call_netdevice_notifiers_extack net/core/dev.c:2244 [inline]
 call_netdevice_notifiers net/core/dev.c:2258 [inline]
 unregister_netdevice_many_notify+0x98a/0x1280 net/core/dev.c:11887
 unregister_netdevice_many net/core/dev.c:11951 [inline]
 unregister_netdevice_queue+0x1f4/0x220 net/core/dev.c:11821
 unregister_netdevice include/linux/netdevice.h:3337 [inline]
 nsim_destroy+0xbd/0x330 drivers/net/netdevsim/netdev.c:1021
 __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_dev_reload_down+0x77/0xa0 drivers/net/netdevsim/dev.c:968
 devlink_reload+0xab/0x5a0 net/devlink/dev.c:461
 devlink_nl_reload_doit+0x4dd/0x8f0 net/devlink/dev.c:584
 genl_family_rcv_msg_doit net/netlink/genetlink.c:1115 [inline]
 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
 genl_rcv_msg+0x620/0x6d0 net/netlink/genetlink.c:1210
 netlink_rcv_skb+0x12c/0x230 net/netlink/af_netlink.c:2533
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]
 netlink_unicast+0x599/0x670 net/netlink/af_netlink.c:1338
 netlink_sendmsg+0x5cc/0x6e0 net/netlink/af_netlink.c:1882
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg+0x140/0x180 net/socket.c:733
 ____sys_sendmsg+0x326/0x4b0 net/socket.c:2573
 ___sys_sendmsg net/socket.c:2627 [inline]
 __sys_sendmsg+0x19d/0x230 net/socket.c:2659
 __do_sys_sendmsg net/socket.c:2664 [inline]
 __se_sys_sendmsg net/socket.c:2662 [inline]
 __x64_sys_sendmsg+0x46/0x50 net/socket.c:2662
 x64_sys_call+0x2734/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811889c810 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+0x21b/0x1700 net/batman-adv/multicast.c:948
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4db/0xa20 kernel/workqueue.c:3319
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3400
 kthread+0x4ae/0x520 kernel/kthread.c:464
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 51 Comm: kworker/u8:3 Not tainted 6.14.0-rc6-syzkaller-00244-g31d7109a19f6 #0
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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