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cgroup: remove subsystem files when remounting cgroup 

cgroup_clear_directroy is called by cgroup_d_remove_dir
and cgroup_remount.

when we call cgroup_remount to remount the cgroup,the subsystem
may be unlinked from cgroupfs_root->subsys_list in rebind_subsystem,this
subsystem's files will not be removed in cgroup_clear_directroy.
And the system will panic when we try to access these files.

this patch removes subsystems's files before rebind_subsystems,
if rebind_subsystems failed, repopulate these removed files.

With help from Tejun.

Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
hifive-unleashed-5.1
Gao feng 2012-12-03 09:28:18 +08:00 committed by Tejun Heo
parent 879a3d9dbb
commit 7083d0378a
1 changed files with 9 additions and 2 deletions
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11
kernel/cgroup.c
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@ -1349,14 +1349,21 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data)
goto out_unlock;
}
/*
* Clear out the files of subsystems that should be removed, do
* this before rebind_subsystems, since rebind_subsystems may
* change this hierarchy's subsys_list.
*/
cgroup_clear_directory(cgrp->dentry, false, removed_mask);
ret = rebind_subsystems(root, opts.subsys_mask);
if (ret) {
/* rebind_subsystems failed, re-populate the removed files */
cgroup_populate_dir(cgrp, false, removed_mask);
drop_parsed_module_refcounts(opts.subsys_mask);
goto out_unlock;
}
/* clear out any existing files and repopulate subsystem files */
cgroup_clear_directory(cgrp->dentry, false, removed_mask);
/* re-populate subsystem files */
cgroup_populate_dir(cgrp, false, added_mask);