From 4528fd0595847c2078b59f24800e751c2d6b7e41 Mon Sep 17 00:00:00 2001
From: Li Zefan <lizf@cn.fujitsu.com>
Date: Tue, 2 Feb 2010 13:44:10 -0800
Subject: [PATCH] cgroups: fix to return errno in a failure path
In cgroup_create(), if alloc_css_id() returns failure, the errno is not
propagated to userspace, so mkdir will fail silently.
To trigger this bug, we mount blkio (or memory subsystem), and create more
then 65534 cgroups. (The number of cgroups is limited to 65535 if a
subsystem has use_id == 1)
# mount -t cgroup -o blkio xxx /mnt
# for ((i = 0; i < 65534; i++)); do mkdir /mnt/$i; done
# mkdir /mnt/65534
(should return ENOSPC)
#
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Paul Menage <menage@google.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
kernel/cgroup.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 1fbcc748044a7..aa3bee5664467 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2936,14 +2936,17 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
for_each_subsys(root, ss) {
struct cgroup_subsys_state *css = ss->create(ss, cgrp);
+
if (IS_ERR(css)) {
err = PTR_ERR(css);
goto err_destroy;
}
init_cgroup_css(css, ss, cgrp);
- if (ss->use_id)
- if (alloc_css_id(ss, parent, cgrp))
+ if (ss->use_id) {
+ err = alloc_css_id(ss, parent, cgrp);
+ if (err)
goto err_destroy;
+ }
/* At error, ->destroy() callback has to free assigned ID. */
}
--
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