==================================================================
BUG: KCSAN: data-race in ext4_ext_insert_extent / ext4_mark_iloc_dirty

write to 0xffff88811e59c48c of 4 bytes by task 14721 on cpu 1:
 ext4_ext_insert_extent+0x1209/0x2b50 fs/ext4/extents.c:2120
 ext4_ext_map_blocks+0x1776/0x20c0 fs/ext4/extents.c:4265
 ext4_map_blocks+0x6a6/0xf60 fs/ext4/inode.c:626
 mpage_map_one_extent+0x16e/0x390 fs/ext4/inode.c:2377
 mpage_map_and_submit_extent fs/ext4/inode.c:2430 [inline]
 ext4_writepages+0xcf6/0x1cb0 fs/ext4/inode.c:2782
 do_writepages+0x7b/0x150 mm/page-writeback.c:2354
 __filemap_fdatawrite_range+0x19b/0x1d0 mm/filemap.c:421
 __filemap_fdatawrite mm/filemap.c:429 [inline]
 filemap_flush+0x1f/0x30 mm/filemap.c:456
 ext4_alloc_da_blocks+0x4c/0x130 fs/ext4/inode.c:3146
 ext4_release_file+0x36/0x180 fs/ext4/file.c:142
 __fput+0x1df/0x460 fs/file_table.c:281
 ____fput+0x11/0x20 fs/file_table.c:314
 task_work_run+0x8e/0x110 kernel/task_work.c:123
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop arch/x86/entry/common.c:216 [inline]
 __prepare_exit_to_usermode+0x1c8/0x230 arch/x86/entry/common.c:246
 __syscall_return_slowpath arch/x86/entry/common.c:329 [inline]
 do_syscall_64+0xb9/0x120 arch/x86/entry/common.c:368
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88811e59c48c of 4 bytes by task 14727 on cpu 0:
 ext4_do_update_inode fs/ext4/inode.c:5042 [inline]
 ext4_mark_iloc_dirty+0xcb2/0x1630 fs/ext4/inode.c:5624
 __ext4_mark_inode_dirty+0x2b9/0x3f0 fs/ext4/inode.c:5818
 ext4_dirty_inode+0xa6/0xc0 fs/ext4/inode.c:5854
 __mark_inode_dirty+0x72/0x7d0 fs/fs-writeback.c:2258
 mark_inode_dirty include/linux/fs.h:2192 [inline]
 generic_write_end+0x174/0x2a0 fs/buffer.c:2203
 ext4_da_write_end+0x55e/0x6d0 fs/ext4/inode.c:3092
 generic_perform_write+0x233/0x380 mm/filemap.c:3310
 ext4_buffered_write_iter+0x2b1/0x390 fs/ext4/file.c:270
 ext4_file_write_iter+0x4a3/0xfd0 fs/ext4/file.c:498
 call_write_iter include/linux/fs.h:1907 [inline]
 do_iter_readv_writev+0x321/0x3c0 fs/read_write.c:694
 do_iter_write+0x10e/0x470 fs/read_write.c:999
 vfs_iter_write+0x4c/0x70 fs/read_write.c:1040
 iter_file_splice_write+0x41a/0x770 fs/splice.c:750
 do_splice_from fs/splice.c:846 [inline]
 direct_splice_actor+0x95/0x160 fs/splice.c:1016
 splice_direct_to_actor+0x365/0x660 fs/splice.c:971
 do_splice_direct+0xf2/0x170 fs/splice.c:1059
 do_sendfile+0x562/0xb10 fs/read_write.c:1521
 __do_sys_sendfile64 fs/read_write.c:1576 [inline]
 __se_sys_sendfile64 fs/read_write.c:1568 [inline]
 __x64_sys_sendfile64+0xa9/0x130 fs/read_write.c:1568
 do_syscall_64+0x71/0x120 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 14727 Comm: syz-executor.4 Not tainted 5.8.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================