Hello, On Tue, Jul 18, 2017 at 04:29:40PM -0400, Waiman Long wrote: > I think the kernfs_activate() call is for the cgroup1 mount of debug kernfs_activate() there is for any files which are created while a controller moves between hierarchies, so, yeah, during boot, this is where the root files for cgroup1 hierarchies would be activated. > cgroup which probably failed as I put debug in the cgroup_no_v1= option. Yeah, they just get skipped over. > The RHEL7 system that I ran the test on tried to do v1-mount of all the > cgroup controllers available. I am also wondering how a v1-mount of > debug controller will make the controller files appear on cgroup2 root. > Maybe I miss something in the code. When a controller gets mounted on v1, the controller is detached from cgroup2 hierarchy, so the corresponding files are removed from v2 root and then created on v1, which are activated by the kernfs_activate() call at the end of rebind. > My test kernel was built out of your latest cgroup git tree with the > thread mode patches on (review-cgroup2-threads-v3 branch). I see. I'm testing with the same kernel. > As I said above, I put in the kernel command line option > "cgroup_no_v1=pids,debug,memory". Then I mounted the cgroup2 filesystem > after boot. > > # mount -t cgroup2 cgroup2 /cgroup2 > # ls /cgroup2/ > cgroup.controllers cgroup.procs cgroup.subtree_control cgroup.threads > # echo +memory > /cgroup2/cgroup.subtree_control > # ls /cgroup2/ > cgroup.controllers debug.current_css_set > cgroup.procs debug.current_css_set_cg_links > cgroup.subtree_control debug.current_css_set_refcount > cgroup.threads debug.masks > debug.csses debug.taskcount > debug.css_links Heh, I'm really confused. If I do the same thing, I get the following result which makes sense as the files would be activated in cgroup_apply_cftypes() when the debug controller is registered during boot. # mkdir /cgroup2 # mount -t cgroup2 cgroup2 /cgroup2 # ls /cgroup2/ cgroup.controllers debug.current_css_set cgroup.procs debug.current_css_set_cg_links cgroup.subtree_control debug.current_css_set_refcount cgroup.threads debug.masks debug.csses debug.taskcount debug.css_links Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
