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commit 4a12178d3dd5b06a215076c60dc7cb124d711373
cgroup: Add generic cgroup subsystem permission checks
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On Monday, October 8, 2012 5:56:35 AM UTC-7, John Tapsell wrote:
>
> Thanks for the help Glenn - I now have more details.
>
> The process triggering the warning is system_server, and this is running
> as user "system".
>
> It is trying to write the pid of various other processes
> (com.android.inputmethod.latin, com.android.phone. com.android.launcher,
> etc) into /dev/inputctl/tasks
>
> But these other processes have a different uid (they run as user app_16,
> app_20, radio, etc)
>
> So the kernel/cgroups.c file does:
>
> if (cred->euid &&
> cred->euid != tcred->uid &&
> cred->euid != tcred->suid) {
> rcu_read_unlock();
> cgroup_unlock();
> return -EACCES;
> }
>
> It fails on the uid check, and returns an error. (I put a printk here to
> confirm this, and confirm the difference in euid and uid)
>
> Is system_server supposed to be running as user "system", and is it
> supposed to be trying to change the cgroup of process owned by another user?
>
> Thanks,
>
> John
>
> On Friday, 5 October 2012 17:14:25 UTC+1, Glenn Kasten wrote:
>>
>> I suggest getting a stack trace at the time of log, to see what is
>> happening.
>> For example at that ALOGE also log the tid and fd, and then do an abort()
>> or *(char*) 0 = 0;
>> This will prevent the system from running of course, but a logcat during
>> bootup should show why it's failing.
>>
>>
>> On Wednesday, October 3, 2012 2:10:48 PM UTC-7, John Tapsell wrote:
>>>
>>> Hi Glenn,
>>>
>>> Can you give any more hints about what to look for in init.rc ? The
>>> cgroups code is exactly the same in my init.rc
>>>
>>> I have:
>>>
>>> > ls -l /dev/cpuctl/tasks
>>>
>>> -rwxrwxrwx system system 0 2000-01-01 00:23 tasks
>>>
>>> Yet I still get:
>>>
>>> W/SchedPolicy( 189): add_tid_to_cgroup failed to write '435'
>>> (Permission denied); background=0
>>>
>>> etc.
>>>
>>> Any ideas please?
>>>
>>> John
>>>
>>>
>>>
>>> On Monday, 13 August 2012 17:44:35 UTC+1, Glenn Kasten wrote:
>>>>
>>>> Sometimes this is caused by incorrect init.rc. Make sure your init.rc
>>>> has all of the latest changes from system/core/rootdir/init.rc especially
>>>> if you have forked it.
>>>>
>>>> You mentioned a "lot of people" have seen this .. were these on other
>>>> external postings or bug reports? if so can you please supply a link to
>>>> these, it will help diagnose to see the other reports.
>>>>
>>>> On Friday, August 10, 2012 2:46:18 AM UTC-7, failuch wrote:
>>>>>
>>>>> Hello all,
>>>>>
>>>>> I saw that a lot of people encountered these error :
>>>>>
>>>>> W/ActivityManager( 349): Failed setting process group of 4911 to 0
>>>>> W/SchedPolicy( 349): add_tid_to_cgroup failed to write '4911'
>>>>> (Permission denie
>>>>> d); background=1
>>>>>
>>>>>
>>>>>
>>>>> And I was unable to find explanation/solution for this problem,
>>>>> although
>>>>>
>>>>> I have checked cgroups are mounted and /dev/cpuctl/tasks exist
>>>>>
>>>>> Can you please to comment ?
>>>>>
>>>>>
>>>>> ThX
>>>>>
>>>>
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