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BUG: KCSAN: data-race in alloc_empty_file / percpu_counter_add_batch

read to 0xffffffff85c08548 of 8 bytes by task 15890 on cpu 1:
 get_nr_files fs/file_table.c:66 [inline]
 alloc_empty_file+0x2d/0x180 fs/file_table.c:142
 alloc_file+0x4e/0x2b0 fs/file_table.c:193
 alloc_file_pseudo+0x11c/0x1b0 fs/file_table.c:232
 sock_alloc_file+0x69/0x130 net/socket.c:398
 __sys_socketpair+0x258/0x450 net/socket.c:1595
 __do_sys_socketpair net/socket.c:1624 [inline]
 __se_sys_socketpair net/socket.c:1621 [inline]
 __x64_sys_socketpair+0x5e/0x80 net/socket.c:1621
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffffffff85c08548 of 8 bytes by task 15892 on cpu 0:
 percpu_counter_add_batch+0xca/0x150 lib/percpu_counter.c:91
 percpu_counter_add include/linux/percpu_counter.h:55 [inline]
 percpu_counter_inc include/linux/percpu_counter.h:179 [inline]
 alloc_empty_file+0xd2/0x180 fs/file_table.c:153
 alloc_file+0x4e/0x2b0 fs/file_table.c:193
 alloc_file_pseudo+0x11c/0x1b0 fs/file_table.c:232
 create_pipe_files+0x22a/0x3b0 fs/pipe.c:867
 __do_pipe_flags+0x51/0x180 fs/pipe.c:900
 do_pipe2+0x3f/0x150 fs/pipe.c:948
 __do_sys_pipe fs/pipe.c:971 [inline]
 __se_sys_pipe fs/pipe.c:969 [inline]
 __x64_sys_pipe+0x2a/0x40 fs/pipe.c:969
 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: 0 PID: 15892 Comm: syz-executor.5 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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