From 7083d0378a1746f2b45729cae494c6b92e75d73f Mon Sep 17 00:00:00 2001 From: Gao feng Date: Mon, 3 Dec 2012 09:28:18 +0800 Subject: [PATCH] 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 Signed-off-by: Tejun Heo --- kernel/cgroup.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index e1293a9189b6..5cc37241a6fb 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -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); -- 2.20.1