about process lockup (state 'getblk')

[Rina]

i saw recently a few posts about some processes freezing (getting into
state 'getblk' for a long time) while scanning some large directories.
i'm facing the same problem on a 4.6-release while scanning using 'find'
and piping to remove large, nested directories on a local filesystem. it
got into the state 'biowr' after half hour or so.

there's no error message in dmesg nor /var/log/messages. is this one of
the known issues? can anybody advise on how to investigate where the
freezing/lock up may occur, or what the most feasible workaround is?

thanks.

Rina