Re: Deadlock possibly caused by too_many_isolated.

[Minchan Kim]

Hi Wu,

On Tue, Oct 19, 2010 at 11:35 AM, Wu Fengguang <fengguang.wu@xxxxxxxxx> wrote:
>> @@ -2054,10 +2069,11 @@ rebalance:
>>                 goto got_pg;
>>
>>         /*
>> -        * If we failed to make any progress reclaiming, then we are
>> -        * running out of options and have to consider going OOM
>> +        * If we failed to make any progress reclaiming and there aren't
>> +        * many parallel reclaiming, then we are unning out of options and
>> +        * have to consider going OOM
>>          */
>> -       if (!did_some_progress) {
>> +       if (!did_some_progress && !too_many_isolated_zone(preferred_zone)) {
>>                 if ((gfp_mask & __GFP_FS) && !(gfp_mask & __GFP_NORETRY)) {
>>                         if (oom_killer_disabled)
>>                                 goto nopage;
>
> This is simply wrong.
>
> It disabled this block for 99% system because there won't be enough
> tasks to make (!too_many_isolated_zone == true). As a result the LRU
> will be scanned like mad and no task get OOMed when it should be.

If !too_many_isolated_zone is false, it means there are already many
direct reclaiming tasks.
So they could exit reclaim path and !too_many_isolated_zone will be true.
What am I missing now?


> Thanks,
> Fengguang
>



-- 
Kind regards,
Minchan Kim
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