On 07/18/2017 04:12 PM, Tejun Heo wrote: > Hello, > > On Tue, Jul 18, 2017 at 04:00:45PM -0400, Waiman Long wrote: >> From my own debugging, the controller files (e.g. the debug controller) >> were indirectly populated by the rebind_subsystems() call. >> >> [ 1.628103] css_populate_dir: init subsystem debug > ... >> [ 1.654975] cgroup_apply_control_enable+0x103/0x340 >> [ 1.657719] cgroup_apply_control+0x1a/0x30 >> [ 1.658521] rebind_subsystems+0x18a/0x3b0 > ... > > But there's kernfs_activate() call at the end of rebind_subsystems(), > so if the files were being added there, it should have been activated > there and I can confirm that the files are correctly added / removed > from the cgroup2 root directory when controllers are attached to / > detached from it. I think the kernfs_activate() call is for the cgroup1 mount of debug cgroup which probably failed as I put debug in the cgroup_no_v1= option. 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. >> For the default cgroup2 root, kernfs_activate() was only called at the >> beginning in cgroup_init() with only the base cgroup files added. No >> more call after that until I touched the cgroup.subtree_control file. > Hmm... we're activating at the end of > > * cgroup_setup_root() > * rebind_subsystems() > * cgroup_subtree_control_write() > * cgroup_apply_cftypes() after successful addition > * cgroup_mkdir() > > I *think* this should cover everything. Just in case, are you looking > at the mainline kernel? Can you share how you can reproduce the > issue? My test kernel was built out of your latest cgroup git tree with the thread mode patches on (review-cgroup2-threads-v3 branch). 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 Cheers, Longman -- 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
