syzbot

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BUG: KCSAN: data-race in xprt_connect / xprt_unlock_connect

write to 0xffff8880259ffcc0 of 8 bytes by task 8485 on cpu 1:
 xprt_unlock_connect+0x7b/0x150 net/sunrpc/xprt.c:820
 xs_udp_setup_socket+0x347/0x410 net/sunrpc/xprtsock.c:2059
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2272
 worker_thread+0x635/0xb90 kernel/workqueue.c:2418
 kthread+0x1fa/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffff8880259ffcc0 of 8 bytes by task 10641 on cpu 0:
 xprt_release_write net/sunrpc/xprt.c:386 [inline]
 xprt_connect+0x2ec/0x4d0 net/sunrpc/xprt.c:870
 call_connect+0x105/0x150 net/sunrpc/clnt.c:2056
 __rpc_execute+0x11c/0x950 net/sunrpc/sched.c:886
 rpc_execute+0xc5/0x140 net/sunrpc/sched.c:962
 rpc_run_task+0x375/0x390 net/sunrpc/clnt.c:1140
 rpc_call_sync net/sunrpc/clnt.c:1169 [inline]
 rpc_ping net/sunrpc/clnt.c:2685 [inline]
 rpc_create_xprt+0x1c3/0x410 net/sunrpc/clnt.c:477
 rpc_create+0x346/0x430 net/sunrpc/clnt.c:593
 nfs_create_rpc_client+0x2a8/0x330 fs/nfs/client.c:536
 nfs_init_client+0x3d/0xa0 fs/nfs/client.c:653
 nfs_get_client+0x869/0x940 fs/nfs/client.c:430
 nfs_init_server fs/nfs/client.c:692 [inline]
 nfs_create_server+0x44b/0xfe0 fs/nfs/client.c:996
 nfs_try_get_tree+0x19d/0x6c0 fs/nfs/super.c:939
 nfs_get_tree+0xa48/0xa70 fs/nfs/fs_context.c:1347
 vfs_get_tree+0x4a/0x190 fs/super.c:1549
 do_new_mount fs/namespace.c:2875 [inline]
 path_mount+0x119d/0x1c10 fs/namespace.c:3205
 do_mount fs/namespace.c:3218 [inline]
 __do_sys_mount fs/namespace.c:3426 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3403
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3403
 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: 0 PID: 10641 Comm: syz-executor.4 Not tainted 5.10.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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