Hello, I had a little application making use of pid and mount namespaces to isolate some processes on some machines. This all worked well on 3.7 boxes. A coworker upgraded his machine and noticed that things weren't working anymore on 3.8. The symptom he noticed is that remounting /proc inside the namespaced process broke the /proc of the original namespace. (Remounting /proc is necessary for the pid namespace to be really effective)
There is a simple way to reproduce the issue if you have a new enough util-linux where the unshare utility accepts the --pid option. Try that: bash-4.2$ unshare --pid --mount -bash-4.2$ sudo mount -t proc /proc /proc [sudo] password for friss: sudo: unable to send audit message: Operation not permitted -bash-4.2$ [ The audit failure is already a sign of something going wrong more on that bellow. ] Then in another terminal running in the root namesapce: bash-4.2$ ls -l /proc/self ls: cannot read symbolic link /proc/self: No such file or directory lrwxrwxrwx 1 root root 0 Jun 1 23:37 /proc/self As you see, remounting /proc in the private namespace broke the root /proc... Now the namespace isn't functional anyway even if /proc doesn't get remounted: bash-4.2$ unshare --pid --mount -bash-4.2$ id uid=1001(friss) gid=1001(friss) groups=1001(friss),10(wheel) -bash-4.2$ id -bash: fork: Cannot allocate memory -bash-4.2$ It's able to run one process, but every following invocation will fail. I suppose the audit issue mentioned above is just another symptom. All of this was working fine on 3.7 kernels. I tried it on latest 3.8 and 3.9 and it fails on both. My application didn't make use of unshare, but instead forked a new process with the namespacing flags. The symptoms are identical in both cases. Fred. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
