Re: [3.6 regression?] THP + migration/compaction livelock (I think)

[Andy Lutomirski]

On Sun, Nov 18, 2012 at 2:55 PM, David Rientjes <rientjes@xxxxxxxxxx> wrote:
> On Sat, 17 Nov 2012, Marc Duponcheel wrote:
>
>> # echo always >/sys/kernel/mm/transparent_hugepage/enabled
>> # while [ 1 ]
>>   do
>>    sleep 10
>>    date
>>    echo = vmstat
>>    egrep "(thp|compact)" /proc/vmstat
>>    echo = khugepaged stack
>>    cat /proc/501/stack
>>  done > /tmp/49361.xxxx
>> # emerge icedtea
>> (where 501 = pidof khugepaged)
>>
>> for xxxx = base = 3.6.6
>> and xxxx = test = 3.6.6 + diff you provided
>>
>> I attach
>>  /tmp/49361.base.gz
>> and
>>  /tmp/49361.test.gz
>>
>> Note:
>>
>>  with xxx=base, I could see
>>   PID USER      PR  NI  VIRT  RES  SHR S  %CPU %MEM     TIME+ COMMAND
>>  8617 root      20   0 3620m  41m  10m S 988.3  0.5   6:19.06 javac
>>     1 root      20   0  4208  588  556 S   0.0  0.0   0:03.25 init
>>  already during configure and I needed to kill -9 javac
>>
>>  with xxx=test, I could see
>>   PID USER      PR  NI  VIRT  RES  SHR S  %CPU %MEM     TIME+ COMMAND
>> 9275 root      20   0 2067m 474m  10m S 304.2  5.9   0:32.81 javac
>>  710 root       0 -20     0    0    0 S   0.3  0.0   0:01.07 kworker/0:1H
>>  later when processing >700 java files
>>
>> Also note that with xxx=test compact_blocks_moved stays 0
>>
>
> Sounds good!  Andy, have you had the opportunity to try to reproduce your
> issue with the backports that Mel listed?  I think he'll be considering
> asking for some of these to be backported for a future stable release so
> any input you can provide would certainly be helpful.

I've had an impressive amount of trouble even reproducing it on 3.6.
Apparently I haven't hid the magic combination yet.  I'll give it
another try soon.

-- 
Andy Lutomirski
AMA Capital Management, LLC
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