From: James Bottomley <James.Bottomley-d9PhHud1JfjCXq6kfMZ53/egYHeGw8Jk@public.gmane.org>
To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Aleksa Sarai <asarai-l3A5Bk7waGM@public.gmane.org>,
Greg Kroah-Hartman
<gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>,
Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>,
Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>,
"Serge E. Hallyn"
<serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA@public.gmane.org>,
Aditya Kali <adityakali-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
Chris Wilson
<chris-Y6uKTt2uX1cEflXRtASbqLVCufUGDwFn@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Christian Brauner <cbrauner-l3A5Bk7waGM@public.gmane.org>,
dev-IGmTWi+3HBZvNhPySn5qfx2eb7JE58TQ@public.gmane.org
Subject: Re: [PATCH v1 3/3] cgroup: relax common ancestor restriction for direct descendants
Date: Thu, 21 Jul 2016 08:34:36 -0700 [thread overview]
Message-ID: <1469115276.2331.23.camel@HansenPartnership.com> (raw)
In-Reply-To: <20160721152648.GA23759-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
On Thu, 2016-07-21 at 11:26 -0400, Tejun Heo wrote:
> Hello, James.
>
> On Thu, Jul 21, 2016 at 08:16:34AM -0700, James Bottomley wrote:
> > > That'd be one side. The other side is the one moving. Let's say
> > > the system admin thing wants to move all processe from A proper
> > > to B. It would do that by draining processes from A's procs
> > > file into B's and even that is multistep and can race.
> >
> > So the second part is that once we allow the creation of
> > subdirectories, there's no unified tasks file, so there's no way of
> > draining A proper without enumerating and descending into the
> > cgroupns created subtrees in A?
>
> Not that. If it races, it will end up moving processes which are no
> longer in A proper.
So if I as the cgroup ns owner am moving a task from A to A_subdir, the
admin scanning tasks in all of A may miss this task in motion because
all the tasks files can't be scanned atomically?
James
WARNING: multiple messages have this Message-ID (diff)
From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Tejun Heo <tj@kernel.org>
Cc: Aleksa Sarai <asarai@suse.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Li Zefan <lizefan@huawei.com>,
Johannes Weiner <hannes@cmpxchg.org>,
"Serge E. Hallyn" <serge.hallyn@ubuntu.com>,
Aditya Kali <adityakali@google.com>,
Chris Wilson <chris@chris-wilson.co.uk>,
linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
Christian Brauner <cbrauner@suse.de>,
dev@opencontainers.org
Subject: Re: [PATCH v1 3/3] cgroup: relax common ancestor restriction for direct descendants
Date: Thu, 21 Jul 2016 08:34:36 -0700 [thread overview]
Message-ID: <1469115276.2331.23.camel@HansenPartnership.com> (raw)
In-Reply-To: <20160721152648.GA23759@htj.duckdns.org>
On Thu, 2016-07-21 at 11:26 -0400, Tejun Heo wrote:
> Hello, James.
>
> On Thu, Jul 21, 2016 at 08:16:34AM -0700, James Bottomley wrote:
> > > That'd be one side. The other side is the one moving. Let's say
> > > the system admin thing wants to move all processe from A proper
> > > to B. It would do that by draining processes from A's procs
> > > file into B's and even that is multistep and can race.
> >
> > So the second part is that once we allow the creation of
> > subdirectories, there's no unified tasks file, so there's no way of
> > draining A proper without enumerating and descending into the
> > cgroupns created subtrees in A?
>
> Not that. If it races, it will end up moving processes which are no
> longer in A proper.
So if I as the cgroup ns owner am moving a task from A to A_subdir, the
admin scanning tasks in all of A may miss this task in motion because
all the tasks files can't be scanned atomically?
James
next prev parent reply other threads:[~2016-07-21 15:34 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-18 16:18 [PATCH v1 0/3] cgroup: allow for unprivileged management Aleksa Sarai
2016-07-18 16:18 ` [PATCH v1 1/3] kernfs: add support for custom per-sb permission hooks Aleksa Sarai
[not found] ` <20160718161816.13040-1-asarai-l3A5Bk7waGM@public.gmane.org>
2016-07-18 16:18 ` [PATCH v1 2/3] cgroup: allow for unprivileged subtree management Aleksa Sarai
2016-07-18 16:18 ` Aleksa Sarai
[not found] ` <20160718161816.13040-3-asarai-l3A5Bk7waGM@public.gmane.org>
2016-07-20 15:45 ` Tejun Heo
2016-07-20 15:45 ` Tejun Heo
[not found] ` <20160720154557.GF4574-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
2016-07-20 22:59 ` Aleksa Sarai
2016-07-20 22:59 ` Aleksa Sarai
2016-07-18 16:18 ` [PATCH v1 3/3] cgroup: relax common ancestor restriction for direct descendants Aleksa Sarai
2016-07-18 16:18 ` Aleksa Sarai
[not found] ` <20160718161816.13040-4-asarai-l3A5Bk7waGM@public.gmane.org>
2016-07-20 15:51 ` Tejun Heo
2016-07-20 15:51 ` Tejun Heo
[not found] ` <20160720155147.GG4574-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
2016-07-20 22:58 ` Aleksa Sarai
2016-07-20 22:58 ` Aleksa Sarai
[not found] ` <6e975d80-4077-fb8b-ec84-708e37c8e149-l3A5Bk7waGM@public.gmane.org>
2016-07-20 23:02 ` Tejun Heo
2016-07-20 23:02 ` Tejun Heo
[not found] ` <20160720230228.GA19588-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2016-07-20 23:18 ` Aleksa Sarai
2016-07-20 23:18 ` Aleksa Sarai
[not found] ` <982fcf3a-3685-9bd7-dd95-7bff255c9421-l3A5Bk7waGM@public.gmane.org>
2016-07-20 23:19 ` Tejun Heo
2016-07-20 23:19 ` Tejun Heo
[not found] ` <20160720231949.GB19588-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2016-07-21 7:49 ` Aleksa Sarai
2016-07-21 7:49 ` Aleksa Sarai
[not found] ` <379e5b13-29d4-ca75-1935-0a64f3db8d27-l3A5Bk7waGM@public.gmane.org>
2016-07-21 14:33 ` Serge E. Hallyn
2016-07-21 14:33 ` Serge E. Hallyn
[not found] ` <20160721143330.GA5751-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2016-07-21 14:37 ` Aleksa Sarai
2016-07-21 14:37 ` Aleksa Sarai
[not found] ` <2dc90947-cee7-90a9-3e60-4ca7c0de29d3-l3A5Bk7waGM@public.gmane.org>
2016-07-21 15:01 ` Tejun Heo
2016-07-21 15:01 ` Tejun Heo
2016-07-21 15:09 ` Serge E. Hallyn
2016-07-21 15:09 ` Serge E. Hallyn
2016-07-21 14:51 ` James Bottomley
2016-07-21 14:51 ` James Bottomley
[not found] ` <1469112709.2331.11.camel-d9PhHud1JfjCXq6kfMZ53/egYHeGw8Jk@public.gmane.org>
2016-07-21 14:59 ` Tejun Heo
2016-07-21 14:59 ` Tejun Heo
[not found] ` <20160721145905.GC22680-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
2016-07-21 15:07 ` Aleksa Sarai
2016-07-21 15:07 ` Aleksa Sarai
2016-07-21 15:04 ` Tejun Heo
2016-07-21 14:52 ` Tejun Heo
2016-07-21 14:52 ` Tejun Heo
[not found] ` <20160721145242.GB22680-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
2016-07-21 15:04 ` James Bottomley
2016-07-21 15:04 ` James Bottomley
[not found] ` <1469113456.2331.16.camel-d9PhHud1JfjCXq6kfMZ53/egYHeGw8Jk@public.gmane.org>
2016-07-21 15:07 ` Tejun Heo
2016-07-21 15:07 ` Tejun Heo
[not found] ` <20160721150740.GF22680-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
2016-07-21 15:16 ` James Bottomley
2016-07-21 15:16 ` James Bottomley
2016-07-21 15:26 ` Tejun Heo
[not found] ` <20160721152648.GA23759-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
2016-07-21 15:34 ` James Bottomley [this message]
2016-07-21 15:34 ` James Bottomley
[not found] ` <1469115276.2331.23.camel-d9PhHud1JfjCXq6kfMZ53/egYHeGw8Jk@public.gmane.org>
2016-07-21 15:50 ` Tejun Heo
2016-07-21 15:50 ` Tejun Heo
[not found] ` <20160721155046.GB23759-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
2016-07-21 18:16 ` James Bottomley
2016-07-21 18:16 ` James Bottomley
[not found] ` <1469125002.2331.54.camel-d9PhHud1JfjCXq6kfMZ53/egYHeGw8Jk@public.gmane.org>
2016-07-21 21:06 ` Tejun Heo
2016-07-21 21:06 ` Tejun Heo
2016-07-22 8:30 ` Aleksa Sarai
[not found] ` <177bbc17-5c75-1ff8-0b1f-0c5601fa7e6b-l3A5Bk7waGM@public.gmane.org>
2016-07-25 18:38 ` Tejun Heo
2016-07-25 18:38 ` Tejun Heo
[not found] ` <20160725183801.GE19588-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2016-07-25 22:54 ` Serge E. Hallyn
2016-07-25 22:54 ` Serge E. Hallyn
2016-07-22 8:24 ` Aleksa Sarai
2016-07-22 8:24 ` Aleksa Sarai
2016-07-25 18:44 ` Tejun Heo
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