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From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: "Michael Kerrisk (man-pages)"
	<mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Roman Gushchin <guro-b10kYP2dOMg@public.gmane.org>,
	"Serge E. Hallyn" <serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org>,
	linux-man <linux-man-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	lkml <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	"open list:CONTROL GROUP (CGROUP)"
	<cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: cgroups(7): documenting /sys/kernel/cgroup files
Date: Wed, 10 Jan 2018 09:39:42 -0800	[thread overview]
Message-ID: <20180110173942.GH3668920@devbig577.frc2.facebook.com> (raw)
In-Reply-To: <20180110173340.GG3668920-4dN5La/x3IkLX0oZNxdnEQ2O0Ztt9esIQQ4Iyu8u01E@public.gmane.org>

Hello, again.

On Wed, Jan 10, 2018 at 09:33:40AM -0800, Tejun Heo wrote:
> Hello, Michael.
> 
> On Wed, Jan 10, 2018 at 06:31:20PM +0100, Michael Kerrisk (man-pages) wrote:
> > So, I am confused. According to Documentation/cgroup-v2.txt,
> > cgoup.threads is delegated:
> > 
> > [[
> > Model of Delegation
> > ~~~~~~~~~~~~~~~~~~~
> > 
> > A cgroup can be delegated in two ways.  First, to a less privileged
> > user by granting write access of the directory and its "cgroup.procs",
> > "cgroup.threads" and "cgroup.subtree_control" files to the user.
> > Second, if the "nsdelegate" mount option is set, automatically to a
> > cgroup namespace on namespace creation.
> > ]]
> > 
> > So, is that a mistake in that text file?
> 
> Yes, it is.  I probably copy&pasted from an earlier version where we
> were marking threaded domains instead of threaded roots.  Will fix it
> right away.

Jesus christ, sorry.  Roman and the document are right.

* cgroup.type is not delegatble, marking it threaded makes the cgroup
  join the parent's domain.

* cgroup.threads is delegatable, because marking the child cgroups as
  threaded make them join the subtree root, and the threads can be
  dispersed across the parent - the delegated root here - and the
  subtree of the child which is marked threaded.

I'll apply Roman's patch.  Sorry about the confusion.

Thanks.

-- 
tejun
--
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WARNING: multiple messages have this Message-ID (diff)
From: Tejun Heo <tj@kernel.org>
To: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Cc: Roman Gushchin <guro@fb.com>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	linux-man <linux-man@vger.kernel.org>,
	lkml <linux-kernel@vger.kernel.org>,
	"open list:CONTROL GROUP (CGROUP)" <cgroups@vger.kernel.org>
Subject: Re: cgroups(7): documenting /sys/kernel/cgroup files
Date: Wed, 10 Jan 2018 09:39:42 -0800	[thread overview]
Message-ID: <20180110173942.GH3668920@devbig577.frc2.facebook.com> (raw)
In-Reply-To: <20180110173340.GG3668920@devbig577.frc2.facebook.com>

Hello, again.

On Wed, Jan 10, 2018 at 09:33:40AM -0800, Tejun Heo wrote:
> Hello, Michael.
> 
> On Wed, Jan 10, 2018 at 06:31:20PM +0100, Michael Kerrisk (man-pages) wrote:
> > So, I am confused. According to Documentation/cgroup-v2.txt,
> > cgoup.threads is delegated:
> > 
> > [[
> > Model of Delegation
> > ~~~~~~~~~~~~~~~~~~~
> > 
> > A cgroup can be delegated in two ways.  First, to a less privileged
> > user by granting write access of the directory and its "cgroup.procs",
> > "cgroup.threads" and "cgroup.subtree_control" files to the user.
> > Second, if the "nsdelegate" mount option is set, automatically to a
> > cgroup namespace on namespace creation.
> > ]]
> > 
> > So, is that a mistake in that text file?
> 
> Yes, it is.  I probably copy&pasted from an earlier version where we
> were marking threaded domains instead of threaded roots.  Will fix it
> right away.

Jesus christ, sorry.  Roman and the document are right.

* cgroup.type is not delegatble, marking it threaded makes the cgroup
  join the parent's domain.

* cgroup.threads is delegatable, because marking the child cgroups as
  threaded make them join the subtree root, and the threads can be
  dispersed across the parent - the delegated root here - and the
  subtree of the child which is marked threaded.

I'll apply Roman's patch.  Sorry about the confusion.

Thanks.

-- 
tejun

  parent reply	other threads:[~2018-01-10 17:39 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-08 21:11 cgroups(7): documenting /sys/kernel/cgroup files Michael Kerrisk (man-pages)
2018-01-08 21:11 ` Michael Kerrisk (man-pages)
2018-01-09 11:28 ` Roman Gushchin
2018-01-09 11:28   ` Roman Gushchin
     [not found]   ` <20180109112811.GA31373-B3w7+ongkCiLfgCeKHXN1g2O0Ztt9esIQQ4Iyu8u01E@public.gmane.org>
2018-01-09 18:52     ` Michael Kerrisk (man-pages)
2018-01-09 18:52       ` Michael Kerrisk (man-pages)
     [not found] ` <ff431fd8-f1c1-ed8d-2d69-64ea83a8a505-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2018-01-10  4:23   ` Michael Kerrisk (man-pages)
2018-01-10  4:23     ` Michael Kerrisk (man-pages)
2018-01-10 12:44     ` Roman Gushchin
2018-01-10 12:44       ` Roman Gushchin
     [not found]       ` <20180110124407.GA26913-B3w7+ongkCiLfgCeKHXN1g2O0Ztt9esIQQ4Iyu8u01E@public.gmane.org>
2018-01-10 14:02         ` Tejun Heo
2018-01-10 14:02           ` Tejun Heo
2018-01-10 14:32           ` Roman Gushchin
2018-01-10 17:31           ` Michael Kerrisk (man-pages)
     [not found]             ` <CAKgNAkhDY09gauX-1Ut4SoL9DEoxj9wJ8SjS6h-Ntc90xeWi1A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-01-10 17:33               ` Tejun Heo
2018-01-10 17:33                 ` Tejun Heo
     [not found]                 ` <20180110173340.GG3668920-4dN5La/x3IkLX0oZNxdnEQ2O0Ztt9esIQQ4Iyu8u01E@public.gmane.org>
2018-01-10 17:39                   ` Tejun Heo [this message]
2018-01-10 17:39                     ` Tejun Heo
     [not found]           ` <20180110140239.GX3668920-4dN5La/x3IkLX0oZNxdnEQ2O0Ztt9esIQQ4Iyu8u01E@public.gmane.org>
2018-01-10 17:44             ` Tejun Heo
2018-01-10 17:44               ` Tejun Heo
     [not found]               ` <20180110174457.GI3668920-4dN5La/x3IkLX0oZNxdnEQ2O0Ztt9esIQQ4Iyu8u01E@public.gmane.org>
2018-01-10 19:14                 ` Michael Kerrisk (man-pages)
2018-01-10 19:14                   ` Michael Kerrisk (man-pages)
2018-01-10 17:45       ` Tejun Heo

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