BUG: KCSAN: data-race in prandom_seed / prandom_u32

read to 0xffff888237c28848 of 8 bytes by task 3183 on cpu 1:
 prandom_seed+0xbb/0x270 lib/random32.c:439
 addrconf_dad_begin net/ipv6/addrconf.c:3975 [inline]
 addrconf_dad_work+0x265/0xbb0 net/ipv6/addrconf.c:4100
 process_one_work+0x3d3/0x720 kernel/workqueue.c:2289
 worker_thread+0x618/0xa70 kernel/workqueue.c:2436
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30

write to 0xffff888237c28848 of 8 bytes by task 1964 on cpu 0:
 siprand_u32 lib/random32.c:372 [inline]
 prandom_u32+0x10e/0x190 lib/random32.c:387
 mld_ifc_start_work net/ipv6/mcast.c:1071 [inline]
 mld_ifc_work+0x6dd/0x800 net/ipv6/mcast.c:2656
 process_one_work+0x3d3/0x720 kernel/workqueue.c:2289
 worker_thread+0x618/0xa70 kernel/workqueue.c:2436
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30

value changed: 0xc84fa857de86d87b -> 0xbbc494319de7bbed

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1964 Comm: kworker/0:8 Not tainted 5.18.0-rc5-syzkaller-00178-g30c8e80f7932-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: mld mld_ifc_work
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