syzbot

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BUG: KCSAN: data-race in xprt_clear_locked / xprt_prepare_transmit

read to 0xffff8881041a2cc0 of 8 bytes by task 7411 on cpu 0:
 xprt_lock_write net/sunrpc/xprt.c:303 [inline]
 xprt_prepare_transmit+0x6c/0x120 net/sunrpc/xprt.c:1366
 call_connect+0xfc/0x1a0 net/sunrpc/clnt.c:2088
 __rpc_execute+0xf5/0x610 net/sunrpc/sched.c:922
 rpc_execute+0x1b5/0x1c0 net/sunrpc/sched.c:997
 rpc_run_task+0x379/0x440 net/sunrpc/clnt.c:1133
 rpc_call_sync+0xa7/0x130 net/sunrpc/clnt.c:1162
 rpc_ping net/sunrpc/clnt.c:2714 [inline]
 rpc_create_xprt+0x376/0x3d0 net/sunrpc/clnt.c:482
 rpc_create+0x296/0x4a0 net/sunrpc/clnt.c:595
 nfs_create_rpc_client+0x348/0x3c0 fs/nfs/client.c:522
 nfs_init_client fs/nfs/client.c:637 [inline]
 nfs_init_client+0x69/0xc0 fs/nfs/client.c:624
 nfs_get_client+0x7a6/0x8c0 fs/nfs/client.c:422
 nfs_init_server+0x1c0/0x790 fs/nfs/client.c:675
 nfs_create_server+0xcc/0x3d0 fs/nfs/client.c:962
 nfs_try_mount+0xa0/0x560 fs/nfs/super.c:1904

write to 0xffff8881041a2cc0 of 8 bytes by task 1515 on cpu 1:
 xprt_clear_locked+0x24/0xb0 net/sunrpc/xprt.c:184
 __xprt_lock_write_next+0xb5/0xd0 net/sunrpc/xprt.c:329
 xprt_release_xprt net/sunrpc/xprt.c:358 [inline]
 xprt_release_xprt+0x56/0x70 net/sunrpc/xprt.c:354
 xprt_release_write net/sunrpc/xprt.c:385 [inline]
 xprt_release_write net/sunrpc/xprt.c:380 [inline]
 xprt_autoclose+0x139/0x150 net/sunrpc/xprt.c:658
 process_one_work+0x3d4/0x890 kernel/workqueue.c:2269
 worker_thread+0xa0/0x800 kernel/workqueue.c:2415
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 1515 Comm: kworker/u5:0 Not tainted 5.3.0+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: xprtiod xprt_autoclose
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