Tejun Heo <tj@xxxxxxxxxx> writes: > Hey, > > On Tue, Aug 11, 2015 at 2:57 PM, Eric W. Biederman > <ebiederm@xxxxxxxxxxxx> wrote: >>> So, this somehow ends up confusing upstart on centos6 based systems >>> making it fail to mount tmpfs on /sys/fs/cgroup. It also skips sunrpc >>> and other mounts are different too. No idea why at this point. Can >>> we please revert this from -stable until we know what's going on? >> >> *Boggle* >> >> The only time this should prevent anything is when in a container when >> you are not global root. And then only mounting sysfs should be >> affected. > > This is just plain boot. No namespace involved. > >> The only difference in executed code really should be setting an extra >> flag on the kernfs, inode. The kernfs changes will also refuse to add >> entries to these directories (but these directories are empty). > > Why do we have this in -stable then? Is this part of a larger fix? It is. This patch is part of the prep work to prevent unprivileged users not mounting sysfs (using user namespace permissions) when they should not be allowed to. >> If this is causing problems I don't have a problem with a revert but >> reverts take a minute, and this seems to be the first report of this >> kind. Can we take a minute and attempt to get a coherent explanation. >> >> It should be a matter of moments to debug this >> issue (once a test environment is setup), and see what is wrong and then >> we can act intelligently. Tracing a single system call is not difficult. > > I'm already out today so it'll have to wait till tomorrow. > >> If there really is some weird issue I want to know what it is. > > Sure, but you wanna do that in -stable? Before fixing anything I want a bug report that is clear enough to be reproducible. I just went and attempted to reproduce this, and on RHEL6 workstation (aka my work laptop), using the todays 4.2.0-rc6+ aka edf15b4d4b01b565cb5f4fd2e2d08940b9f92e2f and all of the mounts in /proc/self/mounts are the same between 4.2.0-rc6 and the RHEL6 stock 2.6.32-504.30.3.el6.x86_64, including the cgroups mounted on /cgroup. Which means that I don't have any reason to believe that normal CentOS 6 is broken. Which -stable kernel are you having problems with? Perhaps it was a broken backport? Is it possible this is a local CentOS 6 hack that is breaking? Perhaps a patch you apply on top of your -stable kernel? Certainly with cgroups expected to be mounted at /sys/fs/cgroup there has clearly been at least one change from the stock configuration. I think it is a little less serious if stock CentOS 6 doesn't have problems. Unless it is a conflict of kernel patches I definitely think whatever it is needs to be fixed. Eric -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
