[CRIU] [PATCH 2/2] remap: add a dead pid /proc remap

[Pavel Emelyanov]

On 09/10/2014 07:51 PM, Tycho Andersen wrote:
> On Wed, Sep 10, 2014 at 07:21:55PM +0400, Pavel Emelyanov wrote:
>>
>>> @@ -227,6 +228,28 @@ static int open_remap_linked(struct reg_file_info *rfi,
>>>  	return 0;
>>>  }
>>>  
>>> +static int open_remap_dead_process(struct reg_file_info *rfi,
>>> +		RemapFilePathEntry *rfe)
>>> +{
>>> +	struct pstree_item *helper;
>>> +
>>> +	helper = alloc_pstree_item_with_rst();
>>> +	if (!helper)
>>> +		return -1;
>>> +
>>> +	helper->sid = root_item->sid;
>>> +	helper->pgid = root_item->sid;
>>> +	helper->pid.virt = rfe->remap_id;
>>
>> BTW, a helper with such pid may already be in the tree. E.g.
>> you have a dead task with pid 20 and living task with pgid 20.
>> In this case CRIU would create a helper with pid 20 to make
>> the pgid restore for the latter one work.
> 
> Good point. Another possibility is that two other tasks have the same
> dead pid's files open. This code should check to see if the pid is
> already in the tree as a TASK_HELPER before it adds one, I suppose.

Yes you're right, this is also possible. Maybe this causes the bug
on session test Andrey pointed out.

> Tycho
> 
>>> +	helper->state = TASK_HELPER;
>>> +	helper->parent = root_item;
>>> +	list_add_tail(&helper->sibling, &root_item->children);
>>> +	task_entries->nr_helpers++;
>>> +
>>> +	pr_info("Added a helper for restoring /proc/%d\n", helper->pid.virt);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>>  static int collect_one_remap(void *obj, ProtobufCMessage *msg)
>>>  {
>>>  	int ret = -1;
>>
>