huge cpu and memory usage by ld.so ?

[Luigi Rizzo]

On RELENG_7 (various versions between june and a few days ago) i
noticed that sometimes ld.so starts using huge amounts of memory
and CPU, both in terms of SIZE and RES.

I saw it first on 3 different machines doing a portupgrade -a
while X was active, but perhaps it is Xorg-related because even
stopping portupgrade the phenomenon continues, and the Xorg process
also comes next in terms of CPU usage (not memory though, it stays
down to reasonable levels).

This is the 'top' output during a portupgrade -a

  PID USERNAME    THR PRI NICE   SIZE    RES STATE  C   TIME   WCPU COMMAND
17385 luigi         1 107    0  2027M   220M RUN    1  19:20 51.37% ld-2.3.6.so

and it really goes up with time, at perhaps 50-100Mbytes per minute.

2 of the machines use the nvidia-driver, one is a Dell X1 laptop
with an i915 board.
Exiting from X seems to terminate the stray ld.so.

I am not sure how reproducible the thing is, or whether it is
a known issue (perhaps portupgrade is replacing some Xorg component
while the Xorg process is using it ?)

	cheers
	luigi