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BUG: KCSAN: data-race in unix_release_sock / unix_stream_sendpage

write to 0xffff888121f95a6a of 1 bytes by task 10394 on cpu 0:
 unix_release_sock+0x4fd/0x660 net/unix/af_unix.c:542
 unix_release+0x3e/0x70 net/unix/af_unix.c:842
 __sock_release+0x85/0x160 net/socket.c:592
 sock_close+0x24/0x30 net/socket.c:1270
 __fput+0x1e1/0x520 fs/file_table.c:280
 ____fput+0x1f/0x30 fs/file_table.c:313
 task_work_run+0xf6/0x130 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2b4/0x2c0 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x384/0x3a0 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888121f95a6a of 1 bytes by task 10398 on cpu 1:
 unix_stream_sendpage+0x1ed/0x8f0 net/unix/af_unix.c:1920
 kernel_sendpage+0x7b/0xc0 net/socket.c:3776
 sock_sendpage+0x6c/0x90 net/socket.c:937
 pipe_to_sendpage+0x102/0x1a0 fs/splice.c:458
 splice_from_pipe_feed fs/splice.c:512 [inline]
 __splice_from_pipe+0x295/0x4a0 fs/splice.c:636
 splice_from_pipe+0xbb/0x100 fs/splice.c:671
 generic_splice_sendpage+0x45/0x60 fs/splice.c:844
 do_splice_from fs/splice.c:863 [inline]
 direct_splice_actor+0xa0/0xc0 fs/splice.c:1037
 splice_direct_to_actor+0x22b/0x540 fs/splice.c:992
 do_splice_direct+0x161/0x1e0 fs/splice.c:1080
 do_sendfile+0x384/0x7f0 fs/read_write.c:1464
 __do_sys_sendfile64 fs/read_write.c:1525 [inline]
 __se_sys_sendfile64 fs/read_write.c:1511 [inline]
 __x64_sys_sendfile64+0x12a/0x140 fs/read_write.c:1511
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 10398 Comm: syz-executor.3 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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