asgardius/android_kernel_motorola_sm6225
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

cgroup: make cgroup_destroy_locked() test cgroup_is_populated()

Browse source 
cgroup_destroy_locked() currently tests whether any css_sets are
associated to reject removal if the cgroup contains tasks.  This works
because a css_set's refcnt converges with the number of tasks linked
to it and thus there's no css_set linked to a cgroup if it doesn't
have any live tasks.

To help tracking resource usage of zombie tasks, putting the ref of
css_set will be separated from disassociating the task from the
css_set which means that a cgroup may have css_sets linked to it even
when it doesn't have any live tasks.

This patch updates cgroup_destroy_locked() so that it tests
cgroup_is_populated(), which counts the number of populated css_sets,
instead of whether cgrp->cset_links is empty to determine whether the
cgroup is populated or not.  This ensures that rmdirs won't be
incorrectly rejected for cgroups which only contain zombie tasks.

Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Tejun Heo 2015-10-15 16:41:51 -04:00
parent 2ceb231b0a
commit 91486f61f4
1 changed files with 5 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

11
kernel/cgroup.c
View file

@ -4998,16 +4998,15 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
__releases(&cgroup_mutex) __acquires(&cgroup_mutex)
{
struct cgroup_subsys_state *css;
bool empty;
int ssid;
lockdep_assert_held(&cgroup_mutex);
/* css_set_rwsem synchronizes access to ->cset_links */
down_read(&css_set_rwsem);
empty = list_empty(&cgrp->cset_links);
up_read(&css_set_rwsem);
if (!empty)
/*
* Only migration can raise populated from zero and we're already
* holding cgroup_mutex.
*/
if (cgroup_is_populated(cgrp))
return -EBUSY;
/*