==================================================================
BUG: KCSAN: data-race in unix_inflight / wait_for_unix_gc

write to 0xffffffff8456fb54 of 4 bytes by task 3902 on cpu 0:
 unix_inflight+0x1e8/0x280 net/unix/scm.c:63
 unix_attach_fds+0x10c/0x1e0 net/unix/scm.c:121
 unix_scm_to_skb net/unix/af_unix.c:1534 [inline]
 unix_stream_sendmsg+0x56d/0xa90 net/unix/af_unix.c:1877
 sock_sendmsg_nosec net/socket.c:654 [inline]
 sock_sendmsg net/socket.c:674 [inline]
 ____sys_sendmsg+0x360/0x4d0 net/socket.c:2350
 ___sys_sendmsg net/socket.c:2404 [inline]
 __sys_sendmmsg+0x315/0x4b0 net/socket.c:2490
 __do_sys_sendmmsg net/socket.c:2519 [inline]
 __se_sys_sendmmsg net/socket.c:2516 [inline]
 __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2516
 do_syscall_64+0x34/0x50 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffffffff8456fb54 of 4 bytes by task 3885 on cpu 1:
 wait_for_unix_gc+0x24/0x140 net/unix/garbage.c:196
 unix_dgram_sendmsg+0x5f/0x1610 net/unix/af_unix.c:1632
 sock_sendmsg_nosec net/socket.c:654 [inline]
 sock_sendmsg net/socket.c:674 [inline]
 ____sys_sendmsg+0x360/0x4d0 net/socket.c:2350
 ___sys_sendmsg net/socket.c:2404 [inline]
 __sys_sendmmsg+0x315/0x4b0 net/socket.c:2490
 __do_sys_sendmmsg net/socket.c:2519 [inline]
 __se_sys_sendmmsg net/socket.c:2516 [inline]
 __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2516
 do_syscall_64+0x34/0x50 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3885 Comm: syz-executor.3 Not tainted 5.12.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================