per page reference count.

I'm getting a strange problem I cant figure out. When some
processes die I get an assertion failure in free_pset(). The
cause is a per-page structure that has a non-zero reference count.
In this particular case it was the testsh process. I looked at
the page sets before quitting the shell and I noticed that the
highest block in the stack memory region (0x7fff0000 and up)
had a reference count of two. Later on when the pages are
dereferenced, the count drops to one and when the free_pset routine
is called it catches this. I checked the other processes running
at the same time and none of the others seemed to have stack pages
with more than one reference.

Why would the reference count on a stack page by 2?

I dont think this error is due to me since this stuff is all
handled in os/kern/* files which I have not modified. Is this
a known problem? Has it since been fixed? (I'm using the old
sources I got in september).

                               Tim N.
Received on Mon Nov 21 13:45:34 1994