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BUG: KCSAN: data-race in ext4_mark_iloc_dirty / ext4_writepages

write to 0xffff888128f09ac0 of 8 bytes by task 30740 on cpu 1:
 mpage_map_and_submit_extent fs/ext4/inode.c:2477 [inline]
 ext4_writepages+0x12b9/0x1d40 fs/ext4/inode.c:2772
 do_writepages+0x6b/0x170 mm/page-writeback.c:2344
 __filemap_fdatawrite_range+0x1bb/0x220 mm/filemap.c:421
 __filemap_fdatawrite mm/filemap.c:429 [inline]
 filemap_flush+0x2a/0x40 mm/filemap.c:456
 ext4_alloc_da_blocks+0x72/0x170 fs/ext4/inode.c:3146
 ext4_release_file+0x107/0x200 fs/ext4/file.c:142
 __fput+0x1c3/0x4f0 fs/file_table.c:280
 ____fput+0x1b/0x30 fs/file_table.c:313
 task_work_run+0xf5/0x130 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2ae/0x2c0 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x36e/0x390 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888128f09ac0 of 8 bytes by task 30743 on cpu 0:
 ext4_do_update_inode fs/ext4/inode.c:4973 [inline]
 ext4_mark_iloc_dirty+0x7d8/0x1500 fs/ext4/inode.c:5578
 ext4_mark_inode_dirty+0xe6/0x420 fs/ext4/inode.c:5771
 ext4_dirty_inode+0xad/0xd0 fs/ext4/inode.c:5802
 __mark_inode_dirty+0x5b7/0x940 fs/fs-writeback.c:2258
 mark_inode_dirty include/linux/fs.h:2183 [inline]
 generic_write_end+0x1ba/0x1f0 fs/buffer.c:2199
 ext4_da_write_end+0x162/0x670 fs/ext4/inode.c:3092
 generic_perform_write+0x1d7/0x320 mm/filemap.c:3298
 ext4_buffered_write_iter+0x14e/0x280 fs/ext4/file.c:270
 ext4_dio_write_iter fs/ext4/file.c:549 [inline]
 ext4_file_write_iter+0x89b/0xd30 fs/ext4/file.c:640
 call_write_iter include/linux/fs.h:1901 [inline]
 aio_write+0x1de/0x2d0 fs/aio.c:1583
 __io_submit_one fs/aio.c:1831 [inline]
 io_submit_one+0x648/0xd80 fs/aio.c:1878
 __do_sys_io_submit fs/aio.c:1937 [inline]
 __se_sys_io_submit fs/aio.c:1907 [inline]
 __x64_sys_io_submit+0x104/0x2a0 fs/aio.c:1907
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 30743 Comm: syz-executor.1 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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