From 9ccece80ae19ed42439fc0ced76858f189cd41e8 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 28 Jun 2013 16:24:11 -0700 Subject: [PATCH] cgroup: fix cgroup_add_cftypes() error handling cgroup_add_cftypes() uses cgroup_cfts_commit() to actually create the files; however, both functions ignore actual file creation errors and just assume success. This can lead to, for example, blkio hierarchy with some of the cgroups with only subset of interface files populated after cfq-iosched is loaded under heavy memory pressure, which is nasty. This patch updates cgroup_cfts_commit() and cgroup_add_cftypes() to guarantee that all files are created on success and no file is created on failure. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cgroup.c | 26 ++++++++++++++++++-------- 1 file changed, 18 insertions(+), 8 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 9b16d75bec63..36c0ccc921f4 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2836,8 +2836,8 @@ static void cgroup_cfts_prepare(void) mutex_lock(&cgroup_mutex); } -static void cgroup_cfts_commit(struct cgroup_subsys *ss, - struct cftype *cfts, bool is_add) +static int cgroup_cfts_commit(struct cgroup_subsys *ss, + struct cftype *cfts, bool is_add) __releases(&cgroup_mutex) { LIST_HEAD(pending); @@ -2846,12 +2846,13 @@ static void cgroup_cfts_commit(struct cgroup_subsys *ss, struct dentry *prev = NULL; struct inode *inode; u64 update_before; + int ret = 0; /* %NULL @cfts indicates abort and don't bother if @ss isn't attached */ if (!cfts || ss->root == &cgroup_dummy_root || !atomic_inc_not_zero(&sb->s_active)) { mutex_unlock(&cgroup_mutex); - return; + return 0; } /* @@ -2867,10 +2868,13 @@ static void cgroup_cfts_commit(struct cgroup_subsys *ss, inode = root->dentry->d_inode; mutex_lock(&inode->i_mutex); mutex_lock(&cgroup_mutex); - cgroup_addrm_files(root, ss, cfts, is_add); + ret = cgroup_addrm_files(root, ss, cfts, is_add); mutex_unlock(&cgroup_mutex); mutex_unlock(&inode->i_mutex); + if (ret) + goto out_deact; + /* add/rm files for all cgroups created before */ rcu_read_lock(); cgroup_for_each_descendant_pre(cgrp, root) { @@ -2887,15 +2891,19 @@ static void cgroup_cfts_commit(struct cgroup_subsys *ss, mutex_lock(&inode->i_mutex); mutex_lock(&cgroup_mutex); if (cgrp->serial_nr < update_before && !cgroup_is_dead(cgrp)) - cgroup_addrm_files(cgrp, ss, cfts, is_add); + ret = cgroup_addrm_files(cgrp, ss, cfts, is_add); mutex_unlock(&cgroup_mutex); mutex_unlock(&inode->i_mutex); rcu_read_lock(); + if (ret) + break; } rcu_read_unlock(); dput(prev); +out_deact: deactivate_super(sb); + return ret; } /** @@ -2915,6 +2923,7 @@ static void cgroup_cfts_commit(struct cgroup_subsys *ss, int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) { struct cftype_set *set; + int ret; set = kzalloc(sizeof(*set), GFP_KERNEL); if (!set) @@ -2923,9 +2932,10 @@ int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) cgroup_cfts_prepare(); set->cfts = cfts; list_add_tail(&set->node, &ss->cftsets); - cgroup_cfts_commit(ss, cfts, true); - - return 0; + ret = cgroup_cfts_commit(ss, cfts, true); + if (ret) + cgroup_rm_cftypes(ss, cfts); + return ret; } EXPORT_SYMBOL_GPL(cgroup_add_cftypes); -- 2.20.1