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BUG: KCSAN: data-race in __add_to_page_cache_locked / dio_complete

write to 0xffff88811d5a3c18 of 8 bytes by task 14170 on cpu 1:
 __add_to_page_cache_locked+0x2cc/0x6e0 mm/filemap.c:868
 add_to_page_cache_lru+0xa0/0x1b0 mm/filemap.c:919
 generic_file_buffered_read+0xece/0x1fa0 mm/filemap.c:2409
 generic_file_read_iter+0x7d/0x3e0 mm/filemap.c:2507
 call_read_iter include/linux/fs.h:1868 [inline]
 generic_file_splice_read+0x22b/0x310 fs/splice.c:311
 do_splice_to fs/splice.c:889 [inline]
 splice_direct_to_actor+0x2a8/0x660 fs/splice.c:969
 do_splice_direct+0xf2/0x170 fs/splice.c:1078
 do_sendfile+0x56a/0xba0 fs/read_write.c:1238
 __do_sys_sendfile64 fs/read_write.c:1299 [inline]
 __se_sys_sendfile64 fs/read_write.c:1285 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1285
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88811d5a3c18 of 8 bytes by task 14164 on cpu 0:
 dio_complete+0x238/0x480 fs/direct-io.c:291
 do_blockdev_direct_IO+0x111c/0x1300 fs/direct-io.c:1367
 __blockdev_direct_IO+0x5e/0x70 fs/direct-io.c:1393
 blockdev_direct_IO include/linux/fs.h:3082 [inline]
 fat_direct_IO+0x108/0x1c0 fs/fat/inode.c:288
 generic_file_direct_write+0x25e/0x3e0 mm/filemap.c:3404
 __generic_file_write_iter+0x19c/0x330 mm/filemap.c:3591
 generic_file_write_iter+0x2f3/0x3e0 mm/filemap.c:3666
 call_write_iter include/linux/fs.h:1874 [inline]
 do_iter_readv_writev+0x32e/0x3d0 fs/read_write.c:721
 do_iter_write+0x112/0x4b0 fs/read_write.c:847
 vfs_iter_write+0x4c/0x70 fs/read_write.c:888
 iter_file_splice_write+0x41a/0x770 fs/splice.c:769
 do_splice_from fs/splice.c:865 [inline]
 direct_splice_actor+0x95/0x160 fs/splice.c:1035
 splice_direct_to_actor+0x365/0x660 fs/splice.c:990
 do_splice_direct+0xf2/0x170 fs/splice.c:1078
 do_sendfile+0x56a/0xba0 fs/read_write.c:1238
 __do_sys_sendfile64 fs/read_write.c:1299 [inline]
 __se_sys_sendfile64 fs/read_write.c:1285 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1285
 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: 0 PID: 14164 Comm: syz-executor.1 Not tainted 5.9.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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