1 files changed, 17 insertions, 0 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index a7267bfd3765..3737a682cdf5 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -46,6 +46,7 @@
 #include <linux/cgroupstats.h>
 #include <linux/hash.h>
 #include <linux/namei.h>
+#include <linux/smp_lock.h>
 
 #include <asm/atomic.h>
 
@@ -842,6 +843,11 @@ static int parse_cgroupfs_options(char *data,
                                      struct cgroup_sb_opts *opts)
 {
         char *token, *o = data ?: "all";
+        unsigned long mask = (unsigned long)-1;
+
+#ifdef CONFIG_CPUSETS
+        mask = ~(1UL << cpuset_subsys_id);
+#endif
 
         opts->subsys_bits = 0;
         opts->flags = 0;
@@ -886,6 +892,15 @@ static int parse_cgroupfs_options(char *data,
                 }
         }
 
+        /*
+         * Option noprefix was introduced just for backward compatibility
+         * with the old cpuset, so we allow noprefix only if mounting just
+         * the cpuset subsystem.
+         */
+        if (test_bit(ROOT_NOPREFIX, &opts->flags) &&
+            (opts->subsys_bits & mask))
+                return -EINVAL;
+
         /* We can't have an empty hierarchy */
         if (!opts->subsys_bits)
                 return -EINVAL;
@@ -900,6 +915,7 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data)
         struct cgroup *cgrp = &root->top_cgroup;
         struct cgroup_sb_opts opts;
 
+        lock_kernel();
         mutex_lock(&cgrp->dentry->d_inode->i_mutex);
         mutex_lock(&cgroup_mutex);
 
@@ -927,6 +943,7 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data)
         kfree(opts.release_agent);
         mutex_unlock(&cgroup_mutex);
         mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
+        unlock_kernel();
         return ret;
 }