==================================================================
BUG: KCSAN: data-race in __mark_inode_dirty / move_expired_inodes

write to 0xffff888136002778 of 8 bytes by task 3016 on cpu 0:
 move_expired_inodes+0x1ca/0x4a0 fs/fs-writeback.c:1257
 queue_io+0xe1/0x2b0 fs/fs-writeback.c:1304
 wb_writeback+0x255/0x660 fs/fs-writeback.c:1903
 wb_check_start_all fs/fs-writeback.c:2031 [inline]
 wb_do_writeback+0x3f9/0x5d0 fs/fs-writeback.c:2057
 wb_workfn+0xc8/0x430 fs/fs-writeback.c:2091
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2275
 worker_thread+0x616/0xa70 kernel/workqueue.c:2421
 kthread+0x20b/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff888136002778 of 8 bytes by task 12784 on cpu 1:
 __mark_inode_dirty+0xd8/0x6f0 fs/fs-writeback.c:2295
 generic_update_time fs/inode.c:1766 [inline]
 update_time fs/inode.c:1779 [inline]
 file_update_time+0x3a4/0x3e0 fs/inode.c:1995
 file_modified+0x62/0x80 fs/inode.c:2018
 ext4_dio_write_checks fs/ext4/file.c:441 [inline]
 ext4_dio_write_iter fs/ext4/file.c:505 [inline]
 ext4_file_write_iter+0xbab/0x10b0 fs/ext4/file.c:661
 call_write_iter include/linux/fs.h:1977 [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+0x40a/0x750 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+0xf5/0x170 fs/splice.c:979
 do_sendfile+0x7a6/0xe20 fs/read_write.c:1260
 __do_sys_sendfile64 fs/read_write.c:1325 [inline]
 __se_sys_sendfile64 fs/read_write.c:1311 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1311
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 12784 Comm: syz-executor.4 Not tainted 5.12.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================