I have a 3/60 which exhibits this bug where everything using some
shared-library dumps core.  I've seen it on other machines, but so
rarely that I could not "home in" on it.  I have greater hopes now!

Can anyone provide clues as to when this bug does or does not bite?

I've narrowed this down a little:  The evidence I have shows that
one page of a shared library has the wrong contents - consistently.
The FS is OK, because when this bug does NOT occur, everything works
normally.  When this bug DOES occur, then mmap() access to the file
shows the garbage page, and read() access shows the correct content.
(Oh how I wish for coherent VM and buffer cache...)

At the moment I suspect that either pagein is not actually reading
in the page (leaving it's old contents) or the VM system is giving
me the wrong page.  I'm not sure how to find out.

Any help appreciated!
Gordon