Tejun Heo bc183079dd cgroup: Fix dom_cgrp propagation when enabling threaded mode ... commit 479adb89a9 upstream. A cgroup which is already a threaded domain may be converted into a threaded cgroup if the prerequisite conditions are met. When this happens, all threaded descendant should also have their ->dom_cgrp updated to the new threaded domain cgroup. Unfortunately, this propagation was missing leading to the following failure. # cd /sys/fs/cgroup/unified # cat cgroup.subtree_control # show that no controllers are enabled # mkdir -p mycgrp/a/b/c # echo threaded > mycgrp/a/b/cgroup.type At this point, the hierarchy looks as follows: mycgrp [d] a [dt] b [t] c [inv] Now let's make node "a" threaded (and thus "mycgrp" s made "domain threaded"): # echo threaded > mycgrp/a/cgroup.type By this point, we now have a hierarchy that looks as follows: mycgrp [dt] a [t] b [t] c [inv] But, when we try to convert the node "c" from "domain invalid" to "threaded", we get ENOTSUP on the write(): # echo threaded > mycgrp/a/b/c/cgroup.type sh: echo: write error: Operation not supported This patch fixes the problem by * Moving the opencoded ->dom_cgrp save and restoration in cgroup_enable_threaded() into cgroup_{save|restore}_control() so that mulitple cgroups can be handled. * Updating all threaded descendants' ->dom_cgrp to point to the new dom_cgrp when enabling threaded mode. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> Reported-by: Amin Jamali <ajamali@pivotal.io> Reported-by: Joao De Almeida Pereira <jpereira@pivotal.io> Link: https://lore.kernel.org/r/CAKgNAkhHYCMn74TCNiMJ=ccLd7DcmXSbvw3CbZ1YREeG7iJM5g@mail.gmail.com Fixes: 454000adaa ("cgroup: introduce cgroup->dom_cgrp and threaded css_set handling") Cc: stable@vger.kernel.org # v4.14+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2018-10-18 09:16:24 +02:00
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Makefile	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
cgroup-internal.h	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
cgroup-v1.c	cgroup: Fix deadlock in cpu hotplug path	2018-03-03 10:24:26 +01:00
cgroup.c	cgroup: Fix dom_cgrp propagation when enabling threaded mode	2018-10-18 09:16:24 +02:00
cpuset.c	Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2017-09-12 11:30:56 -07:00
debug.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
freezer.c	cgroup: add @flags to css_task_iter_start() and implement CSS_TASK_ITER_PROCS	2017-07-21 11:14:51 -04:00
namespace.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
pids.c	cgroup: implement cgroup v2 thread support	2017-07-21 11:14:51 -04:00
rdma.c	rdmacg: Fixed uninitialized current resource usage	2017-01-10 12:52:32 -05:00