Re: [PATCH] de_thread: Don't confuse users do_each_thread.

[ebiederm@xmission.com (Eric W. Biederman)]

Oleg Nesterov <oleg@tv-sign.ru> writes:

> On 04/10, Eric W. Biederman wrote:
>>
>> I believe this is 2.6.17 material as the bug is present in
>> 2.6.17-rc1 and the fix is simple.
>>
>> ...
>>
>> +		list_del_init(&leader->tasks);
>
> I beleive this is ok for 2.6.17-rc1, but this breaks lockless
> for_each_process/while_each_thread (I am talking about -mm tree).

Agreed.

> Andrew, could you please drop these ones:
>
> 	task-make-task-list-manipulations-rcu-safe-fix.patch
> 	task-make-task-list-manipulations-rcu-safe-fix-fix.patch
>
> Then we need this "patch" for de_thread:
>
> -		list_add_tail_rcu(&current->tasks, &init_task.tasks);
> +		list_replace_rcu(&leader->tasks, &current->tasks);
>  ...
> -		list_del_init(&leader->tasks);
>
> Currently I don't know how the code looks in -mm tree, I lost the plot.


Since the patches don't conflict on context I bet they are
all in there, at the moment.  I am just about to see if I can
sort that out.

Eric