cgroup: fix mount failure in a corner case

Browse source

commit 970317aa48 upstream.

  # cat test.sh
  #! /bin/bash

  mount -t cgroup -o cpu xxx /cgroup
  umount /cgroup

  mount -t cgroup -o cpu,cpuacct xxx /cgroup
  umount /cgroup
  # ./test.sh
  mount: xxx already mounted or /cgroup busy
  mount: according to mtab, xxx is already mounted on /cgroup

It's because the cgroupfs_root of the first mount was under destruction
asynchronously.

Fix this by delaying and then retrying mount for this case.

v3:
- put the refcnt immediately after getting it. (Tejun)

v2:
- use percpu_ref_tryget_live() rather that introducing
  percpu_ref_alive(). (Tejun)
- adjust comment.

tj: Updated the comment a bit.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
[lizf: Backported to 3.15:
 - s/percpu_ref_tryget_live/atomic_inc_not_zero/
 - Use goto instead of calling restart_syscall()
 - Add cgroup_tree_mutex]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Li Zefan 2014-06-30 11:49:58 +08:00 • committed by Greg Kroah-Hartman

parent 7a072684fb

commit f1a6b5ddc3

1 changed files with 25 additions and 0 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

25

kernel/cgroup.c

View file