Re: cgroup attach task - slogging cpu

[Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

Hi Anjana,

> On 10/10, Anjana V Kumar wrote:
> >
> >
> Problem:
> Issue when attaching a single thread to a cgroup if the thread was alredy in the
> cgroup. The check if the thread is already in cgroup in the above case,
> continues to the next thread instead of exciting.

Yes. Thanks.

> @@ -2047,7 +2047,7 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk,
>  		ent.cgrp = task_cgroup_from_root(tsk, root);
>  		/* nothing to do if this task is already in the cgroup */
>  		if (ent.cgrp == cgrp)
> -			continue;
> +			goto next_thread;
>  		/*
>  		 * saying GFP_ATOMIC has no effect here because we did prealloc
>  		 * earlier, but it's good form to communicate our expectations.
> @@ -2055,7 +2055,7 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk,
>  		retval = flex_array_put(group, i, &ent, GFP_ATOMIC);
>  		BUG_ON(retval != 0);
>  		i++;
> -
> +next_thread:

Yes, but you forgot to fix another "continue" after "ent.cgrp == cgrp" ;)

Oleg.