From mboxrd@z Thu Jan 1 00:00:00 1970 From: Waiman Long Subject: Re: [PATCH cgroup/for-4.13-fixes] cgroup: create dfl_root files on subsys registration Date: Tue, 18 Jul 2017 18:09:16 -0400 Message-ID: References: <1500406336-29512-1-git-send-email-longman@redhat.com> <20170718195148.GC3365493@devbig577.frc2.facebook.com> <539870d2-8b85-2f54-61bd-4ba068e75ce0@redhat.com> <20170718201229.GD3365493@devbig577.frc2.facebook.com> <255cc198-2c10-af76-98ca-086807d11540@redhat.com> <20170718205009.GE3365493@devbig577.frc2.facebook.com> <20170718210658.GF3365493@devbig577.frc2.facebook.com> <20170718215746.GG3365493@devbig577.frc2.facebook.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com B90E980476 In-Reply-To: <20170718215746.GG3365493-4dN5La/x3IkLX0oZNxdnEQ2O0Ztt9esIQQ4Iyu8u01E@public.gmane.org> Content-Language: en-US Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Tejun Heo Cc: Li Zefan , Johannes Weiner , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org On 07/18/2017 05:57 PM, Tejun Heo wrote: > On subsystem registration, css_populate_dir() is not called on the new > root css, so the interface files for the subsystem on cgrp_dfl_root > aren't created on registration. This is a residue from the days when > cgrp_dfl_root was used only as the parking spot for unused subsystems, > which no longer is true as it's used as the root for cgroup2. > > This is often fine as later operations tend to create them as a part > of mount (cgroup1) or subtree_control operations (cgroup2); however, > it's not difficult to mount cgroup2 with the controller interface > files missing as Waiman found out. > > Fix it by invoking css_populate_dir() on the root css on subsys > registration. > > Signed-off-by: Tejun Heo > Reported-by: Waiman Long > Cc: stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org # v4.5+ > --- > Hello, Waiman. > > Can you please verify that this fixes the bug? > Yes, this patch fix the problem. Tested-by: Waiman Long