Bug 5694
| Summary: | netstat -p symptom of how /proc/pid/* acts when process is swapped out | ||
|---|---|---|---|
| Product: | [Retired] Red Hat Linux | Reporter: | James Manning <jmm> |
| Component: | net-tools | Assignee: | Michael K. Johnson <johnsonm> |
| Status: | CLOSED CURRENTRELEASE | QA Contact: | |
| Severity: | low | Docs Contact: | |
| Priority: | low | ||
| Version: | 6.1 | ||
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | i386 | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2000-02-08 15:22:22 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
Assigned to dledford Actually, it looks like the core problem is that /proc/$PID/exe, normally symlink to the executable's place in filesystem namespace, goes away for processes with no pages in core. Sorry, ignore that last comment, just strace'd again and netstat *does* use /proc/pid/cmdline :) Closing this bug as our testing showed that this defect is not observed when tested against current 7.2 release. |
Message from netstat -ap (*run as root*): (Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.) Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 1 rtsa1.raleigh.ibm.:1023 vox.raleigh.ibm:printer SYN_SENT 451/lpd [snip] tcp 0 0 rtsa1.raleigh.ibm.:1075 serv15.raleigh.i:telnet ESTABLISHED 1919/ tcp 0 0 rtsa1.raleigh.ibm.:1074 serv15.raleigh.i:telnet ESTABLISHED 1918/telnet [snip] (sorry for any wrapping) I think this means: This is line 387 of netstat.c meaning prg_cache_loaded != 1 Since prg_cache_loaded is set to 1 at line 303, this appears to mean that the prg_cache_add() from line 370 is getting called and hence sets prg_cache_loaded to 2. The prg_cache_add() getting executed doesn't appear to be a big deal since it appears to be the snprintf() call before it that generates the ending of netstat -p output *** After digging through and trying to find patterns, it looks like that any process that has no resident pages in memory (and hence "ps" stat output will show "W") has its accompanying /proc/pid/* entries messed up... in particular, even though this machine has 4 telnet sessions from 4 xterm's to the same machine, 3 of the 4 are swapped out and now their cmdline is empty: [root@rtsa1 /root]# cat /proc/{1919,2024,2040}/cmdline [root@rtsa1 /root]# Yes, this machine *does* swap a lot :) [root@rtsa1 /root]# free total used free shared buffers cached Mem: 64136 61540 2596 17356 1344 24756 -/+ buffers/cache: 35440 28696 Swap: 192772 160108 32664 Hence it looks like netstat (among others) might assume that root can always get valid /proc/*/cmdline entries, although if processes are swapped out that's not the case. Please feel free to reassign this to net-tools and patch netstat.c to simply warn about this case --- netstat.c~1~ Thu Oct 7 15:32:10 1999 +++ netstat.c Thu Oct 7 15:33:52 1999 @@ -384,8 +384,12 @@ geteuid()); } else - fprintf(stderr, _("(Not all processes could be identified, non-owned process info\n" - " will not be shown, you would have to be root to see it all.)\n")); + if(geteuid()) + fprintf(stderr, _("(Not all processes could be identified, non-owned process info\n" + " will not be shown, you would have to be root to see it all.)\n")); + else + fprintf(stderr, _("(Not all processes could be identified because some were swapped out of memory\n")); + } #if HAVE_AFNETROM