syzbot

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BUG: KCSAN: data-race in xprt_connect / xprt_unlock_connect

write to 0xffff88811e933cc0 of 8 bytes by task 30527 on cpu 1:
 xprt_unlock_connect+0x9a/0xd0 net/sunrpc/xprt.c:808
 xs_udp_setup_socket+0xf6/0x3a0 net/sunrpc/xprtsock.c:2077
 process_one_work+0x424/0x930 kernel/workqueue.c:2268
 worker_thread+0x9a/0x7e0 kernel/workqueue.c:2414
 kthread+0x203/0x230 kernel/kthread.c:268
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

read to 0xffff88811e933cc0 of 8 bytes by task 30543 on cpu 0:
 xprt_release_write net/sunrpc/xprt.c:386 [inline]
 xprt_connect+0x306/0x390 net/sunrpc/xprt.c:857
 call_connect+0x106/0x190 net/sunrpc/clnt.c:2090
 __rpc_execute+0xee/0x730 net/sunrpc/sched.c:913
 rpc_execute+0x1a8/0x1c0 net/sunrpc/sched.c:991
 rpc_run_task+0x3d3/0x4a0 net/sunrpc/clnt.c:1140
 rpc_call_sync+0xab/0x130 net/sunrpc/clnt.c:1169
 rpc_ping net/sunrpc/clnt.c:2725 [inline]
 rpc_create_xprt+0x362/0x3c0 net/sunrpc/clnt.c:482
 rpc_create+0x2b5/0x4a0 net/sunrpc/clnt.c:598
 nfs_create_rpc_client+0x3e0/0x450 fs/nfs/client.c:535
 nfs_init_client fs/nfs/client.c:652 [inline]
 nfs_init_client+0x63/0xc0 fs/nfs/client.c:639
 nfs_get_client+0x8f9/0x9e0 fs/nfs/client.c:429
 nfs_init_server+0x202/0x760 fs/nfs/client.c:691
 nfs_create_server+0xc6/0x3b0 fs/nfs/client.c:978
 nfs_try_get_tree+0xa6/0x4c0 fs/nfs/super.c:922
 nfs_get_tree+0x5f2/0xc00 fs/nfs/fs_context.c:1291
 vfs_get_tree+0x52/0x190 fs/super.c:1547
 do_new_mount fs/namespace.c:2816 [inline]
 do_mount+0xff0/0x1590 fs/namespace.c:3141
 __do_sys_mount fs/namespace.c:3350 [inline]
 __se_sys_mount fs/namespace.c:3327 [inline]
 __x64_sys_mount+0x12b/0x1a0 fs/namespace.c:3327
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 30543 Comm: syz-executor.4 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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