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BUG: KCSAN: data-race in alloc_empty_file / percpu_counter_add_batch

read to 0xffffffff85a08548 of 8 bytes by task 24004 on cpu 1:
 get_nr_files fs/file_table.c:66 [inline]
 alloc_empty_file+0x2d/0x180 fs/file_table.c:142
 path_openat+0x74/0x36e0 fs/namei.c:3514
 do_filp_open+0x11e/0x1b0 fs/namei.c:3555
 do_open_execat+0x111/0x3d0 fs/exec.c:857
 __do_execve_file.isra.0+0xe4f/0x11d0 fs/exec.c:1762
 do_execveat_common fs/exec.c:1868 [inline]
 do_execve fs/exec.c:1885 [inline]
 __do_sys_execve fs/exec.c:1961 [inline]
 __se_sys_execve fs/exec.c:1956 [inline]
 __x64_sys_execve+0x62/0x80 fs/exec.c:1956
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffffffff85a08548 of 8 bytes by task 24002 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_dec include/linux/percpu_counter.h:184 [inline]
 file_free fs/file_table.c:57 [inline]
 __fput+0x35d/0x520 fs/file_table.c:298
 ____fput+0x1f/0x30 fs/file_table.c:313
 task_work_run+0xf6/0x130 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x562/0x18f0 kernel/exit.c:817
 do_group_exit+0xb4/0x1c0 kernel/exit.c:921
 __do_sys_exit_group kernel/exit.c:932 [inline]
 __se_sys_exit_group kernel/exit.c:930 [inline]
 __x64_sys_exit_group+0x2e/0x30 kernel/exit.c:930
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 24002 Comm: blkid Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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