The zombie has involved into /dev/null

Wed Nov 16 12:26:12 UTC 2011

On Wednesday 16 November 2011 14:35:04 Ivan Voras wrote:
> So, if I understand you correctly, you are reporting a bug in which a
> jailed process is holding (the jailed instance of) /dev/null open and
> "umount -f" doesn't work on the jailed /dev ?

Hello, Yes, correct.

> 
> On 14/11/2011 23:52, Slono Slono wrote:
> > On one of servers where installed cacti in jail there is strange enough
> > situation. Sometimes processes poller.php haven't time to successful
> > complete until to beginning of the following session (absence of lock is
> > other problem - its ok) therefore processes breed yet won't begin them
> > kill. During such moments appear zombie processes. However, these zombie
> > show that keep devfs the device. Possibly because are started as
> > 
> > php <path_to_poller>/poller.php 2>/dev/null 2>&1
> > 
> > Sending  of any signals (SIGCHILD too) changes nothing. Strange that with
> > -f (force) optons through a umount command is impossible to unmount
> > devfs with which worked as the zombie.
> > 
> > ps axf  shows:
> > ..
> > 
> > 99551  ??  DsJ      0:00.12 /usr/local/bin/php
> > /usr/local/share/cacti/poller.php 99554  ??  ZJ       0:00.02 <defunct>
> > .
> > 
> > lsof -p 99551
> > COMMAND   PID USER   FD   TYPE             DEVICE SIZE/OFF    NODE NAME
> > php     99551 root  cwd   VBAD                                    
> > (revoked) php     99551 root  rtd   VDIR     225,1035534442        3 
> > 678909 /usr/jails/jails/mon php     99551 root  jld   VDIR    
> > 225,1035534442        3  678909 /usr/jails/jails/mon php     99551 root 
> > txt   VREG     225,1035534442  3261754 1620922
> > /usr/jails/jails-data/mon-data/usr/local/bin/php php     99551 root  txt
> >   VREG     225,1035534442   246776  626780
> > /usr/jails/jails-data/mon-data/libexec/ld-elf.so.1 php     99551 root 
> > txt   VREG     225,1035534442    33600  626862
> > /usr/jails/jails-data/mon-data/lib/libcrypt.so.5 php     99551 root  txt
> >   VREG     225,1035534442   377814 1267501
> > /usr/jails/jails-data/mon-data/usr/local/lib/libpcre.so.0 php     99551
> > root  txt   VREG     225,1035534442   150656  626861
> > /usr/jails/jails-data/mon-data/lib/libm.so.5 php     99551 root  txt  
> > VREG     225,1035534442  1495740  649173
> > /usr/jails/jails-data/mon-data/usr/local/lib/libxml2.so.5 php     99551
> > root  txt   VREG     225,1035534442    84848  626828
> > /usr/jails/jails-data/mon-data/lib/libz.so.5 php     99551 root  txt  
> > VREG     225,1035534442  1074175  649584
> > /usr/jails/jails-data/mon-data/usr/local/lib/libiconv.so.3 php     99551
> > root  txt   VREG     225,1035534442  1270640  626857
> > /usr/jails/jails-data/mon-data/lib/libc.so.7 php     99551 root  txt  
> > VREG     225,1035534442    74189  636259
> > /usr/jails/jails-data/mon-data/usr/local/lib/php/20090626/session.so php
> >     99551 root  txt   VREG     225,1035534442    63195  637380
> > /usr/jails/jails-data/mon-data/usr/local/lib/php/20090626/xml.so php    
> > 99551 root  txt   VREG     225,1035534442    40650  638507
> > /usr/jails/jails-data/mon-data/usr/local/lib/php/20090626/snmp.so php   
> >  99551 root  txt   VREG     225,1035534442   337128  665903
> > /usr/jails/jails-data/mon-data/usr/lib/libssl.so.6 php     99551 root 
> > txt   VREG     225,1035534442   730269 8050234
> > /usr/jails/jails-data/mon-data/usr/local/lib/libnetsnmp.so.30 php    
> > 99551 root  txt   VREG     225,1035534442    35264  626850
> > /usr/jails/jails-data/mon-data/lib/libkvm.so.5 php     99551 root  txt  
> > VREG     225,1035534442    19720  626858
> > /usr/jails/jails-data/mon-data/lib/libdevstat.so.7 php     99551 root 
> > txt   VREG     225,1035534442  1693344  626824
> > /usr/jails/jails-data/mon-data/lib/libcrypto.so.6 php     99551 root 
> > txt   VREG     225,1035534442   105904  666224
> > /usr/jails/jails-data/mon-data/usr/lib/libelf.so.1 php     99551 root 
> > txt   VREG     225,1035534442    61034  635955
> > /usr/jails/jails-data/mon-data/usr/local/lib/php/20090626/mysql.so php  
> >   99551 root  txt   VREG     225,1035534442    54114  637132
> > /usr/jails/jails-data/mon-data/usr/local/lib/php/20090626/sockets.so php
> >     99551 root    0u  PIPE 0xfffffe07514ab5b0    16384        
> > ->0xfffffe07514ab708 php     99551 root    1w  VCHR               0,27  
> >    0t0      27 /usr/jails/jails/mon/dev (devfs) (like character special
> > /dev/null) php     99551 root    2w  VCHR               0,27      0t0   
> >   27 /usr/jails/jails/mon/dev (devfs) (like character special /dev/null)
> > php     99551 root    3u  unix 0xfffffe074ad832a8      0t0        
> > ->(none) php     99551 root    5u  PIPE 0xfffffe043c62fcb8        0     
> >    ->0xfffffe043c62fb60
> > 
> > mount -t devfs |grep mon
> > devfs on /usr/jails/jails/mon/dev (devfs, local, multilabel)
> > 
> > umount -f /usr/jails/jails/mon/dev
> > umount: unmount of /usr/jails/jails/mon/dev failed: Device busy
> > 
> > However apparently devfs is unmount when executed jail stop:
> > 
> > ls -la /usr/jails/jails/mon/dev
> > total 5
> > drwxr-xr-x  2 root  wheel  2 Nov 14 22:36 .
> > drwxr-xr-x  3 root  wheel  3 Nov 14 22:36 ..
> > 
> > As can be that zombie blocks devfs or that in system there is an
> > information on active mount when the file system isn't present
> > 
> > PS: FreeBSD 9.0-RC2 amd64
> > 
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