[Virtual-pkg-base-maintainers] Bug#671691: base: SHMEM - nattch not decremented on brk(2) or exit(2)

TxDoc d.adcock at lonestarbio.com
Sat May 5 23:19:42 UTC 2012


Package: base
Severity: normal

Installed MolecModeling package GAMESS which uses SHMEM(2) for transmitting data between
concurrent processes (master/slave).  When the slave process crashes (SIGILL error),
neither it nor the master (which then exits gracefully) decrements the "shm_nattch"
variable in "shmid_ds". (See "man 2 shmat" - "Upon _exit(2)...".)

Restarting the machine does not clear the shmem table entry (entries); neither does a
complete power-off / reboot sequence.

Subsequent to reboot, the command "ipcs -a" shows the still extant(?) shared
memory segments.

The command "ipcrm -m <shmid>" appears to function correctly, but a subsequent execution of
"ipcs -a" still shows the shmem segment in the kernel table.


The function "shmdt" is useless, because it does not know the "attach address" of the
shared memory segment from the earlier SHMAT operations.

-- System Information:
Debian Release: 6.0.4
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: powerpc (ppc)

Kernel: Linux 2.6.32-5-powerpc
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash





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