linux-kernel - Re: [PATCHv2 7/7] cgroup: mount cgroupns-root when inside non-init cgroupns

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Date:	Fri, 31 Oct 2014 20:29:15 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	Aditya Kali <adityakali@...gle.com>, Tejun Heo <tj@...nel.org>,
	Li Zefan <lizefan@...wei.com>,
	Serge Hallyn <serge.hallyn@...ntu.com>,
	cgroups@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linux API <linux-api@...r.kernel.org>,
	Ingo Molnar <mingo@...hat.com>,
	Linux Containers <containers@...ts.linux-foundation.org>,
	Rohit Jnagal <jnagal@...gle.com>
Subject: Re: [PATCHv2 7/7] cgroup: mount cgroupns-root when inside non-init cgroupns

On Fri, Oct 31, 2014 at 7:59 PM, Eric W. Biederman
<ebiederm@...ssion.com> wrote:
> Andy Lutomirski <luto@...capital.net> writes:
>>> @@ -1862,6 +1904,7 @@ static struct file_system_type cgroup_fs_type = {
>>>         .name = "cgroup",
>>>         .mount = cgroup_mount,
>>>         .kill_sb = cgroup_kill_sb,
>>> +       .fs_flags = FS_USERNS_MOUNT,
>>
>> Aargh, another one!  Eric, can you either ack or nack my patch?
>> Because if my patch goes in, then this line may need to change.  Or
>> not, but if a stable release with cgroupfs and without my patch
>> happens, then we'll have an ABI break.
>
> cgroupfs has no device nodes.  So as long as we are consistent in any
> given release what happens here is orthogonal.
>
> I don't remember if we have managed to get the original problem fixed
> with the trivial backportable solution.  I think so.

I don't remember.  I think the problem is still there, since I think
my patch still applies, and my patch conflicts with your fix.  It's
been long enough that I'm not sure it's worth applying your patch as
an interim fix.

>
> My apologies for not getting to that I haven't even had time to shepherd
> through the regression associated regression fix.  I probably just lock
> track of them but I haven't found the Tested-By's for it yet.

No worries.  I've tested it, but it's my patch, so there's a big grain
of salt there.  I think Serge tested it, too.

>
> Nor have I had time to dig through and figure out how to safely deal
> with umount -l aka MOUNT_DETACH.

If you're talking about the do_remount_sb thing, that's already in Linus' tree.

>
> Along with the question about what to do with nodev, there is also
> your patch about nosuid.

The nosuid patch has a couple versions, and I'm not sure which version
I prefer.  It's certainly debatable.

>
> Starting in about 5 minutes I am going to be mostly offline until
> sometime in the 3rd week in November as I haul all of my stuff accross
> the country to someplace that actually has winter and my allergies don't
> kill me.

Have fun!

--Andy

>
> I am going to have to review and merge a lot of code as soon as I am
> back to being a programmer full time again.  There is a lot of
> interesting stuff coming in right now.
>
> Eric



-- 
Andy Lutomirski
AMA Capital Management, LLC
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