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BUG: KCSAN: data-race in ext4_dio_write_end_io / ondemand_readahead

write to 0xffff888135d29168 of 8 bytes by task 6571 on cpu 1:
 i_size_write include/linux/fs.h:907 [inline]
 ext4_dio_write_end_io+0xd3/0x100 fs/ext4/file.c:397
 iomap_dio_complete+0xb8/0x3e0 fs/iomap/direct-io.c:78
 iomap_dio_rw+0x56/0x80 fs/iomap/direct-io.c:683
 ext4_dio_write_iter fs/ext4/file.c:564 [inline]
 ext4_file_write_iter+0xab3/0x11f0 fs/ext4/file.c:675
 call_write_iter include/linux/fs.h:2074 [inline]
 do_iter_readv_writev+0x2de/0x380 fs/read_write.c:725
 do_iter_write+0x192/0x5c0 fs/read_write.c:851
 vfs_iter_write+0x4c/0x70 fs/read_write.c:892
 iter_file_splice_write+0x43a/0x790 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x650 fs/splice.c:891
 do_splice_direct+0x106/0x190 fs/splice.c:979
 do_sendfile+0x675/0xc40 fs/read_write.c:1245
 __do_sys_sendfile64 fs/read_write.c:1310 [inline]
 __se_sys_sendfile64 fs/read_write.c:1296 [inline]
 __x64_sys_sendfile64+0x102/0x140 fs/read_write.c:1296
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888135d29168 of 8 bytes by task 6581 on cpu 0:
 i_size_read include/linux/fs.h:885 [inline]
 do_page_cache_ra mm/readahead.c:255 [inline]
 ondemand_readahead+0x498/0x700 mm/readahead.c:551
 page_cache_async_ra+0xb5/0xe0 mm/readahead.c:608
 filemap_readahead mm/filemap.c:2565 [inline]
 filemap_get_pages mm/filemap.c:2605 [inline]
 filemap_read+0x504/0x1430 mm/filemap.c:2676
 generic_file_read_iter+0x72/0x320 mm/filemap.c:2822
 ext4_file_read_iter+0x1db/0x290
 call_read_iter include/linux/fs.h:2068 [inline]
 generic_file_splice_read+0x24f/0x330 fs/splice.c:311
 do_splice_to fs/splice.c:796 [inline]
 splice_direct_to_actor+0x2aa/0x650 fs/splice.c:870
 do_splice_direct+0x106/0x190 fs/splice.c:979
 do_sendfile+0x675/0xc40 fs/read_write.c:1245
 __do_sys_sendfile64 fs/read_write.c:1310 [inline]
 __se_sys_sendfile64 fs/read_write.c:1296 [inline]
 __x64_sys_sendfile64+0x102/0x140 fs/read_write.c:1296
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000285000 -> 0x0000000000294000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 6581 Comm: syz-executor.5 Not tainted 5.17.0-rc2-syzkaller-00060-g88808fbbead4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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