Re: [PATCH 3.4 1/2] cgroup: Take css_set_lock when calling cgroup_css_sets_empty()

[Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

Hi,

On 01/10/2013 03:43 AM, Li Zefan wrote:
> On 2013/1/9 23:03, Hans de Goede wrote:
>> As indicated in the comment above cgroup_css_sets_empty the
>> css_set_lock must be hold when calling it.
>>
>> Signed-off-by: Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>> ---
>>   kernel/cgroup.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/kernel/cgroup.c b/kernel/cgroup.c
>> index c908354..59e711a 100644
>> --- a/kernel/cgroup.c
>> +++ b/kernel/cgroup.c
>> @@ -3980,7 +3980,10 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
>>   	/* the vfs holds both inode->i_mutex already */
>>   again:
>>   	mutex_lock(&cgroup_mutex);
>> -	if (!cgroup_css_sets_empty(cgrp)) {
>> +	read_lock(&css_set_lock);
>> +	ret = cgroup_css_sets_empty(cgrp);
> 
> This function doesn't exist in 3.4.xx kernel! It was introduced by an
> out-of-tree patch, and that patch introduced these two bugs (maybe more).

Ah, I didn't expect the sunxi support patches in linux-sunxi to touch the
cgroup code, but since they also bring in a ton of android stuff they do,
and you're right, this android specific patch is the culprit:
https://github.com/linux-sunxi/linux-sunxi/commit/dbc38c633f4b7abe97c53036df55fbb2040188bc

Sorry about the noise.

Regards,

Hans