From: Lu Jialin <lujialin4@huawei.com>
To: Tejun Heo <tj@kernel.org>, Zefan Li <lizefan.x@bytedance.com>,
Johannes Weiner <hannes@cmpxchg.org>
Cc: <cgroups@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: [QUESTION]cgroup mount return -EBUSY
Date: Fri, 26 Apr 2024 12:55:04 +0800 [thread overview]
Message-ID: <5b5da2d3-37b3-60ee-5a94-149094cbe9dc@huawei.com> (raw)
Hello
I encountered a problem when I try to unmount the subsystem right after
all it's subcgroups are removed, the cgroup_root would remain. Mounting
this subsystem to another cgroup_root would return -EBUSY.
The problem could be reproduced with the following script.
test.sh:
mkdir /tmp/test1
mount -t cgroup -o pids pids /tmp/test1
mkdir /tmp/test1/test
rmdir /tmp/test1/test
umount /tmp/test1
mkdir /tmp/test
mount -t cgroup -o pids,cpu none /tmp/test
test.sh should return this.
mount: mounting none on /tmp/test failed: Device or resource busy.
It seems that when unmounting /tmp/test1, the original cgroup_root for
this PID is not released.
/test # cat /proc/cgroups
#subsys_name hierarchy num_cgroups enabled
cpuset 0 1 1
cpu 0 1 1
cpuacct 0 1 1
blkio 0 1 1
devices 0 1 1
freezer 0 1 1
net_cls 0 1 1
perf_event 0 1 1
net_prio 0 1 1
hugetlb 0 1 1
pids 1 1 1
rdma 0 1 1
misc 0 1 1
debug 0 1 1
next reply other threads:[~2024-04-26 4:55 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-26 4:55 Lu Jialin [this message]
2024-05-06 1:50 ` [QUESTION]cgroup mount return -EBUSY Lu Jialin
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