Re: CGroup Namespaces (v8)

[Dan Williams <dan.j.williams@intel.com>]

On Tue, Dec 22, 2015 at 8:23 PM,  <serge.hallyn@ubuntu.com> wrote:
> Hi,
>
> following is a revised set of the CGroup Namespace patchset which Aditya
> Kali has previously sent.  The code can also be found in the cgroupns.v8
> branch of
>
> https://git.kernel.org/cgit/linux/kernel/git/sergeh/linux-security.git/

Happy New Year!

I'm hitting both a build and boot regression in -next with these
patches.  The bisect log reports:

git bisect skip f176ae3a5df610e0373c39538cc7744c7788b3df
# bad: [54b39d263704b66cc8006ce8f7dd4743fdabae70] cgroup: cgroup
namespace setns support
git bisect bad 54b39d263704b66cc8006ce8f7dd4743fdabae70
# good: [bf9b3590879afbaa54148d817ed68a0b51180375] sched: new clone
flag CLONE_NEWCGROUP for c
group namespace
git bisect good bf9b3590879afbaa54148d817ed68a0b51180375
# only skipped commits left to test
# possible first bad commit:
[54b39d263704b66cc8006ce8f7dd4743fdabae70] cgroup: cgroup namespa
ce setns support
# possible first bad commit:
[f176ae3a5df610e0373c39538cc7744c7788b3df] cgroup: introduce cgro
up namespaces

Where compiling "f176ae3a5df6"  fails with:

kernel/cgroup.c: In function ‘cgroupns_put’:
kernel/cgroup.c:5956:2: error: implicit declaration of function
‘to_cg_ns’ [-Werror=implicit-f
unction-declaration]
 put_cgroup_ns(to_cg_ns(ns));
 ^
kernel/cgroup.c:5956:16: warning: passing argument 1 of
‘put_cgroup_ns’ makes pointer from int
eger without a cast
 put_cgroup_ns(to_cg_ns(ns));
               ^
In file included from kernel/cgroup.c:31:0:
include/linux/cgroup.h:609:60: note: expected ‘struct cgroup_namespace
*’ but argument is of t
ype ‘int’
static inline void put_cgroup_ns(struct cgroup_namespace *ns)
                                                           ^
kernel/cgroup.c: At top level:
kernel/cgroup.c:5964:2: warning: initialization from incompatible pointer type
 .install = cgroupns_install,
 ^
kernel/cgroup.c:5964:2: warning: (near initialization for
‘cgroupns_operations.install’)
cc1: some warnings being treated as errors

...and booting "54b39d263704" fails with the following log:

[ 3.963105] BUG: unable to handle kernel NULL pointer dereference at
0000000000000030
[ 3.963110] IP: [<ffffffff81143f3d>] cgroup_path+0x3d/0x90

https://gist.github.com/djbw/1d30cd323d802e3d9d07