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BUG: KCSAN: data-race in ext4_ext_insert_extent / ext4_mark_iloc_dirty

write to 0xffff88810d70f740 of 4 bytes by task 10958 on cpu 0:
 ext4_ext_store_pblock fs/ext4/ext4_extents.h:255 [inline]
 ext4_ext_insert_extent+0x19b2/0x2b00 fs/ext4/extents.c:2115
 ext4_ext_map_blocks+0x1750/0x1fc0 fs/ext4/extents.c:4259
 ext4_map_blocks+0x6c3/0xf20 fs/ext4/inode.c:625
 mpage_map_one_extent+0x10d/0x390 fs/ext4/inode.c:2376
 mpage_map_and_submit_extent fs/ext4/inode.c:2429 [inline]
 ext4_writepages+0xa2c/0x1e10 fs/ext4/inode.c:2781
 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+0xfc/0x690 fs/ext4/fsync.c:151
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2725 [inline]
 ext4_buffered_write_iter+0x363/0x3b0 fs/ext4/file.c:276
 ext4_file_write_iter+0x480/0x10b0 fs/ext4/file.c:501
 call_write_iter include/linux/fs.h:1887 [inline]
 do_iter_readv_writev+0x2cb/0x360 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+0x42a/0x780 fs/splice.c:769
 do_splice_from fs/splice.c:865 [inline]
 direct_splice_actor+0x95/0x150 fs/splice.c:1035
 splice_direct_to_actor+0x365/0x660 fs/splice.c:990
 do_splice_direct+0xf5/0x170 fs/splice.c:1078
 do_sendfile+0x574/0xb70 fs/read_write.c:1238
 __do_sys_sendfile64 fs/read_write.c:1293 [inline]
 __se_sys_sendfile64 fs/read_write.c:1285 [inline]
 __x64_sys_sendfile64+0xa9/0x130 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 0xffff88810d70f740 of 4 bytes by task 10946 on cpu 1:
 ext4_do_update_inode fs/ext4/inode.c:5042 [inline]
 ext4_mark_iloc_dirty+0xe51/0x1640 fs/ext4/inode.c:5624
 __ext4_mark_inode_dirty+0x4d6/0x5f0 fs/ext4/inode.c:5818
 ext4_dirty_inode+0xa6/0xc0 fs/ext4/inode.c:5854
 __mark_inode_dirty+0x74/0x740 fs/fs-writeback.c:2260
 mark_inode_dirty include/linux/fs.h:2169 [inline]
 generic_write_end+0x15e/0x250 fs/buffer.c:2202
 ext4_da_write_end+0x58d/0x750 fs/ext4/inode.c:3091
 generic_perform_write+0x23e/0x3a0 mm/filemap.c:3544
 ext4_buffered_write_iter+0x2ce/0x3b0 fs/ext4/file.c:269
 ext4_file_write_iter+0x480/0x10b0 fs/ext4/file.c:501
 call_write_iter include/linux/fs.h:1887 [inline]
 do_iter_readv_writev+0x2cb/0x360 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+0x42a/0x780 fs/splice.c:769
 do_splice_from fs/splice.c:865 [inline]
 direct_splice_actor+0x95/0x150 fs/splice.c:1035
 splice_direct_to_actor+0x365/0x660 fs/splice.c:990
 do_splice_direct+0xf5/0x170 fs/splice.c:1078
 do_sendfile+0x574/0xb70 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: 1 PID: 10946 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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