Bug#102437: proc leaks memory with the bootstrap filesystem entry

[Marcus Brinkmann]

Package: hurd
Version: current

Hi,

this is really a nice obscure bug.

Calling proc_getprocinfo on PID 4 (root filesystem server) causes proc
to leak a couple of kilobytes (pages?) each time.  This can easily be
reproduced by

ps -F hurd 0
ps -F hurd 4
ps -F hurd 0

etc.  Do this right after booting, so RSS for proc is still under 1 MB (this
makes it easier to see).  To prove that PID 4 is the only process with this
problem, the below program iterates over all pids.  If you specify any command
line arguments, it will skip PID 4.  In this case, no memory is leaked.

This is most certainly a bootstrap issue.  Interestingly, the same behaviour
is exposed in a sub hurd (for the sub hurds root filesystem and the sub hurds
proc server).  I have no concrete idea yet to what the actual bug is.
Any hints, as always, appreciated.

BTW, fork() makes proc leak memory as well.  Reproduce with "forks 1000 10000".
This seems to be an unrelated bug,
which I plan to investigate after this one is fixed.

Thanks,
Marcus