[$] Dentry negativity
Back in 2017, Waiman Long posted a patch
set placing limits on the number of "negative dentries" stored by the
kernel. The better part of three years later, that work continues with,
seemingly, no better prospects for getting into the mainline. It would be
understandable, though, if many people out there don't really know what
negative dentries are or why kernel developers care about them. That, at
least, can be fixed, even if the underlying problem seems to be more
difficult.