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BUG: KCSAN: data-race in alloc_empty_file / percpu_counter_add_batch

write to 0xffffffff85a08548 of 8 bytes by task 23548 on cpu 1:
 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
 sock_alloc_file+0x65/0x120 net/socket.c:397
 __sys_socketpair+0x293/0x450 net/socket.c:1600
 __do_sys_socketpair net/socket.c:1622 [inline]
 __se_sys_socketpair net/socket.c:1619 [inline]
 __x64_sys_socketpair+0x5e/0x80 net/socket.c:1619
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffffff85a08548 of 8 bytes by task 23654 on cpu 0:
 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_sys_open+0x3b3/0x4f0 fs/open.c:1097
 __do_sys_openat fs/open.c:1124 [inline]
 __se_sys_openat fs/open.c:1118 [inline]
 __x64_sys_openat+0x62/0x80 fs/open.c:1118
 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: 23654 Comm: syz-executor.4 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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