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BUG: KCSAN: data-race in __mark_inode_dirty / move_expired_inodes

write to 0xffff8881017a4888 of 8 bytes by task 1825 on cpu 0:
 move_expired_inodes+0x1ca/0x4c0 fs/fs-writeback.c:1400
 queue_io+0xe1/0x270 fs/fs-writeback.c:1447
 wb_writeback+0x265/0x700 fs/fs-writeback.c:2046
 wb_do_writeback+0x101/0x510 fs/fs-writeback.c:2193
 wb_workfn+0xc8/0x520 fs/fs-writeback.c:2234
 process_one_work+0x3e9/0x8f0 kernel/workqueue.c:2276
 worker_thread+0x636/0xae0 kernel/workqueue.c:2422
 kthread+0x262/0x280 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

read to 0xffff8881017a4888 of 8 bytes by task 13850 on cpu 1:
 __mark_inode_dirty+0xda/0x680 fs/fs-writeback.c:2416
 mark_inode_dirty include/linux/fs.h:2403 [inline]
 generic_write_end+0x157/0x180 fs/buffer.c:2198
 ext4_da_write_end+0x59b/0x730 fs/ext4/inode.c:3110
 generic_perform_write+0x22a/0x3c0 mm/filemap.c:3667
 ext4_buffered_write_iter+0x2f2/0x3f0 fs/ext4/file.c:269
 ext4_file_write_iter+0x2e7/0x11d0 fs/ext4/file.c:519
 call_write_iter include/linux/fs.h:2114 [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+0x773/0xda0 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_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000000007 -> 0x0000000000020087

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 13850 Comm: syz-executor.1 Not tainted 5.14.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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