Re: Userspace checkpoint/restart hack: cryo

[kathys <kathys-8fk3Idey6ehBDgjK7y7TUQ@public.gmane.org>]

Serge E. Hallyn wrote:
> Quoting kathys (kathys-QcUrd9fbWu1x7SfHBjqd8AC/G2K4zDHf@public.gmane.org):
>   
>> Serge E. Hallyn wrote:
>>     
>>> Quoting Nadia Derbey (Nadia.Derbey-6ktuUTfB/bM@public.gmane.org):
>>>   
>>>       
>>>> Serge E. Hallyn wrote:
>>>>     
>>>>         
>>>>> Quoting Nadia Derbey (Nadia.Derbey-6ktuUTfB/bM@public.gmane.org):
>>>>>
>>>>>       
>>>>>           
>>>>>> Cedric Le Goater wrote:
>>>>>>
>>>>>>         
>>>>>>             
>>>>>>>           
>>>>>>>               
>>>>>>>> Looks like it has worked for me (msg1 creates 1000 msg queues, sleeps
>>>>>>>> for a while and then removes the msg queues).
>>>>>>>>             
>>>>>>>>                 
>>>>>>> cool. which kernel are you using ? 
>>>>>>>
>>>>>>> C.
>>>>>>>
>>>>>>>
>>>>>>>           
>>>>>>>               
>>>>>> 2.6.25-mm1 (sorry for the late answer - plenty of days off in 
>>>>>> France in May).
>>>>>>
>>>>>> Regards,
>>>>>> Nadia
>>>>>>         
>>>>>>             
>>>>> I'm playing with features in cryo, and keeping a git tree at:
>>>>>
>>>>> git://git.sr71.net/~hallyn/cryodev.git
>>>>>
>>>>> It's meant to exploit the extras which are in the -lxc kernel at
>>>>> lxc.sf.net.  Current latest kernel patch is at
>>>>> http://lxc.sourceforge.net/patches/2.6.26/2.6.26-rc2-mm1-lxc4/ This -lxc
>>>>> tree contains, for instance, Nadia's next_id patches, exploitation for
>>>>> setting ids for sysvipc and for tasks at fork, and updated ipc_setall
>>>>> patches (also using next_id).  The version of cryo in my git tree
>>>>> exploits these.  If you're root when you restart a task, it will clone a
>>>>> new set of namespaces and recreate your sysvipc objects, and it will
>>>>> reset your pids (even if you're not root if the pids are available).
>>>>>       
>>>>>           
>>>> Serge,
>>>>
>>>> I noticed that the sys_hijack() has disappeared from the lxc dev 
>>>> tree:  would you mind putting it back. I think it might be useful if 
>>>> we want to  start a task in a newly defined cgroup, checkpoint it and 
>>>> then try to  restart it. We will need to 'join' the restarted 
>>>> container to check if  everything has correctly be restarted. Or may 
>>>> be is there another way to  do that?
>>>>     
>>>>         
>>> Well it *could* be done similar to how cryo itself works, by ptracing
>>> the destination task and making it fork a task which execve()s a process
>>> to do the querying.  But yuck.
>>>
>>> Kathy, I'm sorry, I know I asked you to take sys_hijack() out.  Could
>>> you please put it back in?  Preferably at the end of the queue, as I don't
>>> want other patches having to be ported on top of it since its future is
>>> very suspect...  Let me know if you have trouble porting it, but it
>>> should be pretty simple.
>>>   
>>>       
>> I added sys_hijack() (namespaces-introduce-sys_hijack.patch) back, with  
>> a little bit of massaging to get it to port properly (as Cedrics  
>> clone64-change-clone_flag-type-to-u64.patch changes unsigned long to  
>> u64) but was unable to compile. I received the following errors:
>>
>> /scratch/kathys/containers/kernel_trees/upstream/kernel/fork.c: In  
>> function 'do_fork_task':
>> /scratch/kathys/containers/kernel_trees/upstream/kernel/fork.c:1342:  
>> warning: format '%1lx' expects type 'long unsigned int', but argument 3  
>> has type 'u64'
>> /scratch/kathys/containers/kernel_trees/upstream/kernel/fork.c: At top  
>> level:
>> /scratch/kathys/containers/kernel_trees/upstream/kernel/fork.c:1416:  
>> error: conflicting types for 'do_fork'
>>     
>  
>   
>> /scratch/kathys/containers/kernel_trees/upstream/include/linux/sched.h:1868: 
>> error: previous declaration of 'do_fork' was here
>>     
>
> Did you change the do_fork definition in sched.h?
>
> -serge
>
>   
I changed definition in sched.h to match do_fork in fork.c
>> I changed the patch as follows so it would apply properly, but I can't  
>> work out why it breaks now, but not previously:
>>
>> Original patch from 2.6.26-rc2-mm1-lxc3:
>> @@ -1307,13 +1313,8 @@ static int fork_traceflag(unsigned clone
>> return 0;
>> }
>>
>> -/*
>> - * Ok, this is the main fork-routine.
>> - *
>> - * It copies the process, and if successful kick-starts
>> - * it and waits for it to finish using the VM if required.
>> - */
>> -long do_fork(unsigned long clone_flags,
>> +long do_fork_task(struct cgroup *cgroup,
>> + unsigned long clone_flags,
>> unsigned long stack_start,
>> struct pt_regs *regs,
>> unsigned long stack_size,
>>
>>
>> Changed to:
>>
>> @@ -1308,13 +1314,8 @@ static int fork_traceflag(u64 clone_flag
>> return 0;
>> }
>>
>> -/*
>> - * Ok, this is the main fork-routine.
>> - *
>> - * It copies the process, and if successful kick-starts
>> - * it and waits for it to finish using the VM if required.
>> - */
>> -long do_fork(u64 clone_flags,
>> +long do_fork_task(struct cgroup *cgroup,
>> + u64 clone_flags,
>> unsigned long stack_start,
>> struct pt_regs *regs,
>> unsigned long stack_size,
>>
>>
>>
>>     
>>> thanks,
>>> -serge
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>>>
>>>   
>>>       
>
>