toolchain: LLVM 11.0.0
config: defconfig + fuzzing.config + kcsan.config
==================================================================
BUG: KCSAN: data-race in more_used_split+0x38/0x60

race at unknown origin, with read to 0xffff024b434f94c2 of 2 bytes by task 219 on cpu 0:
 more_used_split+0x38/0x60
 virtqueue_get_buf_ctx+0xac/0x734
 virtqueue_get_buf+0x34/0x44
 virtnet_send_command+0x1d8/0x2a8
 virtnet_set_rx_mode+0x2a8/0x3c4
 __dev_set_rx_mode+0x1dc/0x22c
 __dev_mc_add+0xa8/0xcc
 dev_mc_add+0x34/0x44
 igmp6_group_added+0x110/0x20c
 __ipv6_dev_mc_inc+0x5a4/0x628
 __ipv6_sock_mc_join+0x3b0/0x4f0
 ipv6_sock_mc_join+0x40/0x54
 do_ipv6_setsockopt+0x18d0/0x2758
 ipv6_setsockopt+0x70/0x164
 udpv6_setsockopt+0xb0/0xc8
 sock_common_setsockopt+0x80/0x9c
 __sys_setsockopt+0x1ac/0x268
 __arm64_sys_setsockopt+0x78/0x94
 invoke_syscall+0x74/0x1b0
 el0_svc_common+0x1a4/0x1d4
 do_el0_svc+0x4c/0xc8
 el0_svc+0x78/0x238
 el0t_64_sync_handler+0x68/0xac
 el0t_64_sync+0x180/0x184

value changed: 0x0018 -> 0x0019

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 219 Comm: systemd-resolve Not tainted 5.16.0-rc4-00002-g5854738642b4 #1
Hardware name: linux,dummy-virt (DT)
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