On Mon, May 23, 2011 at 9:34 PM, Minchan Kim <minchan.kim@xxxxxxxxx> wrote:
> On Tue, May 24, 2011 at 10:19 AM, Andrew Lutomirski <luto@xxxxxxx> wrote:
>> On Sun, May 22, 2011 at 7:12 PM, Minchan Kim <minchan.kim@xxxxxxxxx> wrote:
>>> Could you test below patch based on vanilla 2.6.38.6?
>>> The expect result is that system hang never should happen.
>>> I hope this is last test about hang.
>>>
>>> Thanks.
>>>
>>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>>> index 292582c..1663d24 100644
>>> --- a/mm/vmscan.c
>>> +++ b/mm/vmscan.c
>>> @@ -231,8 +231,11 @@ unsigned long shrink_slab(struct shrink_control *shrink,
>>> if (scanned == 0)
>>> scanned = SWAP_CLUSTER_MAX;
>>>
>>> - if (!down_read_trylock(&shrinker_rwsem))
>>> - return 1; /* Assume we'll be able to shrink next time */
>>> + if (!down_read_trylock(&shrinker_rwsem)) {
>>> + /* Assume we'll be able to shrink next time */
>>> + ret = 1;
>>> + goto out;
>>> + }
>>>
>>> list_for_each_entry(shrinker, &shrinker_list, list) {
>>> unsigned long long delta;
>>> @@ -286,6 +289,8 @@ unsigned long shrink_slab(struct shrink_control *shrink,
>>> shrinker->nr += total_scan;
>>> }
>>> up_read(&shrinker_rwsem);
>>> +out:
>>> + cond_resched();
>>> return ret;
>>> }
>>>
>>> @@ -2331,7 +2336,7 @@ static bool sleeping_prematurely(pg_data_t
>>> *pgdat, int order, long remaining,
>>> * must be balanced
>>> */
>>> if (order)
>>> - return pgdat_balanced(pgdat, balanced, classzone_idx);
>>> + return !pgdat_balanced(pgdat, balanced, classzone_idx);
>>> else
>>> return !all_zones_ok;
>>> }
>>
>> So far with this patch I can't reproduce the hang or the bogus OOM.
>>
>> To be completely clear, I have COMPACTION, MIGRATION, and THP off, I'm
>> running 2.6.38.6, and I have exactly two patches applied. One is the
>> attached patch and the other is a the fpu.ko/aesni_intel.ko merger
>> which I need to get dracut to boot my box.
>>
>> For fun, I also upgraded to 8GB of RAM and it still works.
>>
>
> Hmm. Could you test it with enable thp and 2G RAM?
> Isn't it a original test environment?
> Please don't change test environment. :)
The test that passed last night was an environment (hardware and
config) that I had confirmed earlier as failing without the patch.
I just re-tested my original config (from a backup -- migration,
compaction, and thp "always" are enabled). I get bogus OOMs but not a
hang. (I'm running with mem=2G right now -- I'll swap the DIMMs back
out later on if you want.)
I attached the bogus OOM (actually several that happened in sequence).
They look readahead-related. There was plenty of free swap space.
--Andy
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