In recent kernel, bdflush(2) syscall is deprecated and not effective to anything.
Adding some statement about this situation to DESCRIPTION or NOTES section will be helpful for readers.
I think affected pages are: bdflush(2) and syscalls(2)
The bdflush(2) man page has long carried this text:
Note: Since Linux 2.6, this system call is deprecated and does
nothing. It is likely to disappear altogether in a future ker‐
nel release. Nowadays, the task performed by bdflush() is han‐
dled by the kernel pdflush thread.
As far as I can see, the system call still exists, at least for x86-32.
If something further has changed (which exact recent kernel version, and, ideally a commit ID), please add this info to this bug.
I'm sorry for I missed the note. I close this bug.