==================================================================
BUG: KCSAN: data-race in mptcp_worker / sk_stream_wait_memory

write to 0xffff88806f15c36a of 1 bytes by task 4763 on cpu 0:
 mptcp_check_for_eof net/mptcp/protocol.c:505 [inline]
 mptcp_worker+0x5c9/0x1070 net/mptcp/protocol.c:1409
 process_one_work+0x3e1/0x9a0 kernel/workqueue.c:2269
 worker_thread+0x665/0xbe0 kernel/workqueue.c:2415
 kthread+0x20d/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff88806f15c36a of 1 bytes by task 30902 on cpu 1:
 sk_stream_wait_memory+0x44d/0x6e0 net/core/stream.c:145
 mptcp_sendmsg+0x7b6/0x1470 net/mptcp/protocol.c:912
 inet6_sendmsg+0x5f/0x80 net/ipv6/af_inet6.c:638
 sock_sendmsg_nosec net/socket.c:651 [inline]
 sock_sendmsg net/socket.c:671 [inline]
 sock_write_iter+0x1a1/0x200 net/socket.c:998
 call_write_iter include/linux/fs.h:1882 [inline]
 new_sync_write fs/read_write.c:503 [inline]
 vfs_write+0x665/0x6f0 fs/read_write.c:586
 ksys_write+0xce/0x180 fs/read_write.c:639
 __do_sys_write fs/read_write.c:651 [inline]
 __se_sys_write fs/read_write.c:648 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:648
 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: 30902 Comm: syz-executor.2 Not tainted 5.9.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================