syzbot

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BUG: KCSAN: data-race in __skb_wait_for_more_packets / unix_release_sock

write to 0xffff88812f95226a of 1 bytes by task 855 on cpu 0:
 unix_release_sock+0x25e/0x650 net/unix/af_unix.c:548
 unix_release+0x2f/0x50 net/unix/af_unix.c:859
 __sock_release net/socket.c:596 [inline]
 sock_close+0x6c/0x150 net/socket.c:1277
 __fput+0x243/0x4d0 fs/file_table.c:281
 ____fput+0x11/0x20 fs/file_table.c:314
 task_work_run+0x8e/0x110 kernel/task_work.c:151
 get_signal+0x3eb/0x1510 kernel/signal.c:2562
 arch_do_signal+0x25/0x260 arch/x86/kernel/signal.c:811
 exit_to_user_mode_loop kernel/entry/common.c:161 [inline]
 exit_to_user_mode_prepare+0xde/0x170 kernel/entry/common.c:191
 syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812f95226a of 1 bytes by task 859 on cpu 1:
 __skb_wait_for_more_packets+0xe0/0x2a0 net/core/datagram.c:106
 unix_dgram_recvmsg+0x1d2/0x840 net/unix/af_unix.c:2112
 unix_seqpacket_recvmsg+0x5a/0x70 net/unix/af_unix.c:2065
 sock_recvmsg_nosec net/socket.c:885 [inline]
 sock_recvmsg net/socket.c:903 [inline]
 sock_read_iter+0x19e/0x1e0 net/socket.c:976
 call_read_iter include/linux/fs.h:1881 [inline]
 generic_file_splice_read+0x22a/0x310 fs/splice.c:311
 sock_splice_read+0xa5/0xb0 net/socket.c:954
 do_splice_to fs/splice.c:788 [inline]
 do_splice+0xcf8/0xf30 fs/splice.c:1093
 __do_splice fs/splice.c:1137 [inline]
 __do_sys_splice fs/splice.c:1343 [inline]
 __se_sys_splice+0x2a6/0x390 fs/splice.c:1325
 __x64_sys_splice+0x74/0x80 fs/splice.c:1325
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 859 Comm: syz-executor.2 Not tainted 5.10.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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