On 08/30/2010 03:01 PM, Ferenc Wagner wrote: > Daniel Lezcano<[email protected]> writes: > >> The cgroup is not removed automatically by the cgroup infrastructure >> when all the tasks die, it's how the cgroup is implemented. So it is >> up to lxc-start to remove the cgroup after the pid 1 of the container >> exits. If lxc-start was killed, this directory will not be removed and >> will stay there. >> >> If you start your container again, lxc-start will try to remove this >> directory if it is present and recreate a new cgroup. > > I understand now, thanks for the clarification! > >> there is a linux specific process control, where the kernel sends a >> signal to a child process when its parent dies. >> >> PR_SET_PDEATHSIG (since Linux 2.1.57) >> Set the parent process death signal of the calling process to >> arg2 (either a signal value in the range 1..maxsig, or 0 to >> clear). This is the signal that the calling process will get >> when its parent dies. This value is cleared for the child of >> a fork(2). >> >> This prctl is used in lxc as a safe guard in case lxc-start is killed >> widely, in order to wipe out container's processes. > > Neat, I again leart something interesting. Thanks! > >> When the container init exits, it sends a SIGKILL to all the child >> processes and reap them (aka wait), that happens at the kernel level >> (zap_pid_ns). Hence, in userspace, when wait('init') returns you have >> the guarantee there are no more processes in the container. > > Thanks for the detailed info, very useful. > >> I meant the prctl(PR_SET_PDEATHSIG) is broken on 2.6.32 > > Beyond repair? 2.6.32 is a long-time-supported branch, the fix should > be backported to it if at all possible. Do you think it is?
The patchset is small, IMHO there is a chance we can have the patchset backported. Serge can give us some clarifications about this I think. Thanks -- Daniel ------------------------------------------------------------------------------ Sell apps to millions through the Intel(R) Atom(Tm) Developer Program Be part of this innovative community and reach millions of netbook users worldwide. Take advantage of special opportunities to increase revenue and speed time-to-market. Join now, and jumpstart your future. http://p.sf.net/sfu/intel-atom-d2d _______________________________________________ Lxc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/lxc-users
