On Sun, Mar 01, 2009 at 02:02:31PM -0600, Serge E. Hallyn wrote: > Quoting Alexey Dobriyan (adobriyan@xxxxxxxxx): > > On Fri, Feb 27, 2009 at 01:31:12AM +0300, Alexey Dobriyan wrote: > > > This is collecting and start of dumping part of cleaned up OpenVZ C/R > > > implementation, FYI. > > > > OK, here is second version which shows what to do with shared objects > > (cr_dump_nsproxy(), cr_dump_task_struct()), introduced more checks > > (still no unlinked files) and dumps some more information including > > structures connections (cr_pos_*) > > > > Dumping pids in under thinking because in OpenVZ pids are saved as > > numbers due to CLONE_NEWPID is not allowed in container. In presense > > of multiple CLONE_NEWPID levels this must present a big problem. Looks > > like there is now way to not dump pids as separate object. > > > > As result, struct cr_image_pid is variable-sized, don't know how this will > > play later. > > > > Also, pid refcount check for external pointers is busted right now, > > because /proc inode pins struct pid, so there is almost always refcount > > vs ->o_count mismatch. > > > > No restore yet. ;-) > > Hi Alexey, > > thanks for posting this. Of course there are some predictable responses > (I like the simplicity of pure in-kernel, Dave will not :) but this > needs to be posted to make us talk about it. > > A few more comments that came to me while looking it over: > > 1. cap_sys_admin check is unfortunate. In discussions about Oren's > patchset we've agreed that not having that check from the outset forces > us to consider security with each new patch and feature, which is a good > thing. Removing CAP_SYS_ADMIN on restore? > 2. if any tasks being checkpointed are frozen, checkpoint has the > side effect of thawing them, right? Haven't tried, but should be a bug, yes. It will be "thaw or kill" depending on "flags". > 3. wrt pids, i guess what you really want is to store the pids from > init_tsk's level down to the task's lowest pid, right? Then you > manually set each of those on restart? Any higher pids of course > don't matter. Yes, numbers are really meant to be from init_tsk level. > 4. do you have any thoughts on what to do with the mntns info at > restart? Will you try to detect mounts which need to be re-created? > How? Haven't thought, but it will be tricky for sure :^) > 5. Since you're always setting f_pos, this won't work straight over > a pipe? Do you figure that's just not a worthwhile feature? So far there were no loops when dumping data structures, but I _think_ there will be some, so seeking over dumpfile would be inevitable. > Were you saying (in response to Dave) that you're having private > discussions about whether to pursue posting this as an alternative > to Oren's patchset? If so, any updates on those discussions? Right now, no. _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
