The patch below does not apply to the 3.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 2a0ff3fbe39bc93f719ff857e5a359d9780579ff Mon Sep 17 00:00:00 2001
From: Jeff Liu <jeff.liu@xxxxxxxxxx>
Date: Sun, 26 May 2013 21:33:09 +0800
Subject: [PATCH] cgroup: warn about mismatching options of a new mount of an
existing hierarchy
With the new __DEVEL__sane_behavior mount option was introduced,
if the root cgroup is alive with no xattr function, to mount a
new cgroup with xattr will be rejected in terms of design which
just fine. However, if the root cgroup does not mounted with
__DEVEL__sane_hehavior, to create a new cgroup with xattr option
will succeed although after that the EA function does not works
as expected but will get ENOTSUPP for setting up attributes under
either cgroup. e.g.
setfattr: /cgroup2/test: Operation not supported
Instead of keeping silence in this case, it's better to drop a log
entry in warning level. That would be helpful to understand the
reason behind the scene from the user's perspective, and this is
essentially an improvement does not break the backward compatibilities.
With this fix, above mount attemption will keep up works as usual but
the following line cound be found at the system log:
[ ...] cgroup: new mount options do not match the existing superblock
tj: minor formatting / message updates.
Signed-off-by: Jie Liu <jeff.liu@xxxxxxxxxx>
Reported-by: Alexey Kodanev <alexey.kodanev@xxxxxxxxxx>
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 31e9ef3..a7c9e6d 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1686,11 +1686,14 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
*/
cgroup_drop_root(opts.new_root);
- if (((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) &&
- root->flags != opts.flags) {
- pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n");
- ret = -EINVAL;
- goto drop_new_super;
+ if (root->flags != opts.flags) {
+ if ((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) {
+ pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n");
+ ret = -EINVAL;
+ goto drop_new_super;
+ } else {
+ pr_warning("cgroup: new mount options do not match the existing superblock, will be ignored\n");
+ }
}
/* no subsys rebinding, so refcounts don't change */
--
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