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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