Commit 4528fd05 authored Feb 02, 2010 by Li Zefan Committed by Linus Torvalds Feb 02, 2010

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>

parent ef2b9b05

kernel/cgroup.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -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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