linux-kernel - Re: [PATCH] ion: Consider ion pool pages as indirectly reclaimable

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Date:   Fri, 27 Apr 2018 10:40:36 +0530
From:   vjitta@...eaurora.org
To:     Laura Abbott <labbott@...hat.com>
Cc:     sumit.semwal@...aro.org, gregkh@...uxfoundation.org,
        arve@...roid.com, tkjos@...roid.com, maco@...roid.com,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        linux-kernel-owner@...r.kernel.org
Subject: Re: [PATCH] ion: Consider ion pool pages as indirectly reclaimable

On 2018-04-25 21:17, Laura Abbott wrote:
> On 04/24/2018 08:43 PM, vjitta@...eaurora.org wrote:
>> From: Vijayanand Jitta <vjitta@...eaurora.org>
>> 
>> An issue is observed where mallocs are failing due to overcommit 
>> failure.
>> The failure happens when there is high ION page pool since ION page
>> pool is not considered reclaimable by the overcommit calculation code.
>> This change considers ion pool pages as indirectly reclaimable and 
>> thus
>> accounted as available memory in the overcommit calculation.
>> 
>> Signed-off-by: Vijayanand Jitta <vjitta@...eaurora.org>
>> ---
>>   drivers/staging/android/ion/ion_page_pool.c | 5 +++++
>>   1 file changed, 5 insertions(+)
>> 
>> diff --git a/drivers/staging/android/ion/ion_page_pool.c 
>> b/drivers/staging/android/ion/ion_page_pool.c
>> index db8f614..9bc56eb 100644
>> --- a/drivers/staging/android/ion/ion_page_pool.c
>> +++ b/drivers/staging/android/ion/ion_page_pool.c
>> @@ -32,6 +32,9 @@ static void ion_page_pool_add(struct ion_page_pool 
>> *pool, struct page *page)
>>   		list_add_tail(&page->lru, &pool->low_items);
>>   		pool->low_count++;
>>   	}
>> +
>> +	mod_node_page_state(page_pgdat(page), 
>> NR_INDIRECTLY_RECLAIMABLE_BYTES,
>> +			    (1 << (PAGE_SHIFT + pool->order)));
>>   	mutex_unlock(&pool->mutex);
>>   }
>>   @@ -50,6 +53,8 @@ static struct page *ion_page_pool_remove(struct 
>> ion_page_pool *pool, bool high)
>>   	}
>>     	list_del(&page->lru);
>> +	mod_node_page_state(page_pgdat(page), 
>> NR_INDIRECTLY_RECLAIMABLE_BYTES,
>> +			    -(1 << (PAGE_SHIFT + pool->order)));
>>   	return page;
>>   }
>> 
> 
> I'm sure this fixes the problem but I don't think we want to
> start throwing page adjustments into Ion. Why isn't this
> memory already considered reclaimable by existing calculations?
> 
> Thanks,
> Laura

You can refer to discussion here https://lkml.org/lkml/2018/3/5/361 
introducing
NR_INDIRECTLY_RECLAIMABLE_BYTES for the memory which is not currently 
considered
as reclaimable

Thanks,
Vijay