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BUG: KCSAN: data-race in ext4_setattr / ext4_writepages

write to 0xffff88810d7d9c10 of 8 bytes by task 14406 on cpu 1:
 i_size_write include/linux/fs.h:870 [inline]
 ext4_setattr+0xe19/0xf60 fs/ext4/inode.c:5483
 notify_change+0x86d/0xa60 fs/attr.c:336
 do_truncate+0xe0/0x120 fs/open.c:64
 handle_truncate fs/namei.c:2912 [inline]
 do_open fs/namei.c:3258 [inline]
 path_openat+0x1a30/0x20a0 fs/namei.c:3371
 do_filp_open+0xbd/0x1d0 fs/namei.c:3398
 do_sys_openat2+0xa3/0x250 fs/open.c:1172
 do_sys_open fs/open.c:1188 [inline]
 __do_sys_creat fs/open.c:1262 [inline]
 __se_sys_creat fs/open.c:1256 [inline]
 __x64_sys_creat+0x62/0x80 fs/open.c:1256
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88810d7d9c10 of 8 bytes by task 14399 on cpu 0:
 i_size_read include/linux/fs.h:848 [inline]
 mpage_submit_page fs/ext4/inode.c:2095 [inline]
 mpage_map_and_submit_buffers fs/ext4/inode.c:2349 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2488 [inline]
 ext4_writepages+0xe21/0x1e70 fs/ext4/inode.c:2801
 do_writepages+0x7b/0x150 mm/page-writeback.c:2352
 __filemap_fdatawrite_range+0x19d/0x1d0 mm/filemap.c:422
 file_write_and_wait_range+0x9f/0x120 mm/filemap.c:761
 ext4_sync_file+0x105/0x6e0 fs/ext4/fsync.c:151
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2737 [inline]
 ext4_buffered_write_iter+0x38f/0x3e0 fs/ext4/file.c:278
 ext4_file_write_iter+0x47a/0x1060 fs/ext4/file.c:503
 call_write_iter include/linux/fs.h:1901 [inline]
 do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740
 do_iter_write+0x112/0x4c0 fs/read_write.c:866
 vfs_iter_write+0x4c/0x70 fs/read_write.c:907
 iter_file_splice_write+0x41a/0x770 fs/splice.c:686
 do_splice_from fs/splice.c:764 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:933
 splice_direct_to_actor+0x345/0x650 fs/splice.c:888
 do_splice_direct+0xf5/0x170 fs/splice.c:976
 do_sendfile+0x5e0/0xcf0 fs/read_write.c:1257
 __do_sys_sendfile64 fs/read_write.c:1312 [inline]
 __se_sys_sendfile64 fs/read_write.c:1304 [inline]
 __x64_sys_sendfile64+0xa9/0x130 fs/read_write.c:1304
 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: 14399 Comm: syz-executor.1 Not tainted 5.11.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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