2.4.20: pids disappear & reappear in /proc

2.4.20: pids disappear & reappear in /proc

[Paolo Campanella]

Hi all

I have a dual-Xeon Intel SMP box running kernel 2.4.20-20.9 (RH9, custom
build enabling some ACPI options etc).

Recently, after a reboot, I've started seeing processes disappear &
reappear in ps output. The problem seems to be in /proc itself, e.g.:

[root@za /]# cat /var/run/httpd-ssl.pid
898
[root@za /]# ls /proc/ | grep 898
[root@za /]# ls /proc/898/
cmdline  cpu  cwd  environ  exe  fd  maps  mem  mounts  root  stat 
statm  status

Process 898 is a 1.3 Apache daemon, so no threading. If I check back
later, this process might have reappeared in ps, but some other process
might have disappeared. Also, some PIDs are duplicated in /proc, but
this duplication comes and goes.

I've done lots of checking for signs of rootkits & exploits, and have
found nothing so far. Maybe hardware failure? Any suggestions welcome.


Thanks

Paolo