From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Hocko Subject: Re: memcg Can't context between v1 and v2 because css->refcnt not released Date: Thu, 10 Aug 2017 09:10:59 +0200 Message-ID: <20170810071059.GC23863@dhcp22.suse.cz> References: Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: wang Yu Cc: Johannes Weiner , Tejun Heo , cgroups@vger.kernel.org, linux-mm@kvack.org On Wed 09-08-17 15:06:34, wang Yu wrote: > Hello Johannes ,Michal,and Tejun: > > i using memcg v1, but some reason i want to context to memcg v2, > but i can't, here is my step: > #cat /proc/cgroups > #subsys_name hierarchy num_cgroups enabled > memory 5 1 1 > #cd /sys/fs/cgroup/memory > #mkdir a > #echo 0 > a/cgroup.procs > #sleep 1 > #echo 0 > cgroup.procs This doesn't do what you think. It will try to add a non-existant pid 0 to the root cgroup. You need to remove cgroup a. Moreover it is possible that the `sleep' command will fault some page cache and that will stay in memcg `a' until there is a memory pressure. cgroup v1 had force_empty knob which you can use to drain the cgroup before removal. Then you should be able to umount the v1 cgroup and mount v2. -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org