cgroup: remove subsystem files when remounting cgroup (7083d037) · Commits · 戴 / test

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>

kernel/cgroup.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -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);

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