On 2014/6/3 21:01, Tejun Heo wrote: > On Tue, Jun 03, 2014 at 12:05:22PM +0800, Li Zefan wrote: >> Before this patch (in a fresh system): >> >> # cat /proc/$$/cgroup >> # mount -t cgroup -o __DEVEL__sane_behavior xxx /cgroup >> # umount /cgroup >> # cat /proc/$$/cgroup >> 0:cpuset,cpu,cpuacct,memory,devices,freezer,net_cls,blkio,perf_event,net_prio,hugetlb:/ >> >> After this patch (in a fresh system): >> >> # cat ... >> # mount ... >> # umount ... >> # cat /proc/$$/cgroup >> # >> >> You won't see the default root after it's umounted. > > Hmmmm... I intentionally left it visible tho. The only reason we gate > its visibility is avoid disturbing userland which doesn't know about > and won't use the unified hierarchy. If the userland starts making > use of it, there's no reason to hide it again especially as that's > consistent with how other hierarchies behave too - they keep showing > up if they have lingering refs. > The example I gave is the same result if sane_behavior is not specified, so this is a behavioural change for the old interface? Do we need a fix like this? diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 3f46165..6f10cff 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1789,6 +1789,9 @@ static void cgroup_kill_sb(struct super_block *sb) else percpu_ref_kill(&root->cgrp.self.refcnt); + if (root == &cgrp_dfl_root && !cgroup_sane_behavior(&root->cgrp)) + cgrp_dfl_root_visible = false; + kernfs_kill_sb(sb); -- 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
