syzbot

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BUG: KCSAN: data-race in xprt_connect / xprt_unlock_connect

write to 0xffff88811f593cc0 of 8 bytes by task 32155 on cpu 0:
 xprt_unlock_connect+0x7b/0x150 net/sunrpc/xprt.c:881
 xs_udp_setup_socket+0x363/0x430 net/sunrpc/xprtsock.c:2061
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2275
 worker_thread+0x616/0xa70 kernel/workqueue.c:2421
 kthread+0x20b/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff88811f593cc0 of 8 bytes by task 1498 on cpu 1:
 xprt_release_write net/sunrpc/xprt.c:447 [inline]
 xprt_connect+0x2ec/0x4d0 net/sunrpc/xprt.c:931
 call_connect+0x105/0x150 net/sunrpc/clnt.c:2053
 __rpc_execute+0x11c/0x950 net/sunrpc/sched.c:891
 rpc_execute+0x104/0x1a0 net/sunrpc/sched.c:968
 rpc_run_task+0x397/0x3b0 net/sunrpc/clnt.c:1140
 rpc_call_sync net/sunrpc/clnt.c:1169 [inline]
 rpc_ping net/sunrpc/clnt.c:2682 [inline]
 rpc_create_xprt+0x1c3/0x420 net/sunrpc/clnt.c:477
 rpc_create+0x34c/0x440 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+0x455/0x1030 fs/nfs/client.c:996
 nfs_try_get_tree+0x19d/0x6c0 fs/nfs/super.c:958
 nfs_get_tree+0xbb2/0xbf0 fs/nfs/fs_context.c:1383
 vfs_get_tree+0x4a/0x1a0 fs/super.c:1497
 do_new_mount fs/namespace.c:2903 [inline]
 path_mount+0x11b9/0x1c00 fs/namespace.c:3233
 do_mount fs/namespace.c:3246 [inline]
 __do_sys_mount fs/namespace.c:3454 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3431
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3431
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 1498 Comm: syz-executor.3 Tainted: G        W         5.12.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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