Re: [PATCH v1] mm: help the ALLOC_HARDER allocation pass the watermarki when CMA on

[Zhaoyang Huang]

On Fri, Mar 23, 2018 at 4:38 PM, Michal Hocko <mhocko@xxxxxxxxxx> wrote:
> On Fri 23-03-18 15:57:32, Zhaoyang Huang wrote:
>> For the type of 'ALLOC_HARDER' page allocation, there is an express
>> highway for the whole process which lead the allocation reach __rmqueue_xxx
>> easier than other type.
>> However, when CMA is enabled, the free_page within zone_watermark_ok() will
>> be deducted for number the pages in CMA type, which may cause the watermark
>> check fail, but there are possible enough HighAtomic or Unmovable and
>> Reclaimable pages in the zone. So add 'alloc_harder' here to
>> count CMA pages in to clean the obstacles on the way to the final.
>
> This is no longer the case in the current mmotm tree. Have a look at
> Joonsoo's zone movable based CMA patchset http://lkml.kernel.org/r/1512114786-5085-1-git-send-email-iamjoonsoo.kim@xxxxxxx
>
Thanks for the information. However, I can't find the commit in the
latest mainline, is it merged?
>> Signed-off-by: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxxxxxx>
>> ---
>>  mm/page_alloc.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index 635d7dd..cc18620 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -3045,8 +3045,11 @@ bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
>>
>>
>>  #ifdef CONFIG_CMA
>> -     /* If allocation can't use CMA areas don't use free CMA pages */
>> -     if (!(alloc_flags & ALLOC_CMA))
>> +     /*
>> +      * If allocation can't use CMA areas and no alloc_harder set for none
>> +      * order0 allocation, don't use free CMA pages.
>> +      */
>> +     if (!(alloc_flags & ALLOC_CMA) && (!alloc_harder || !order))
>>               free_pages -= zone_page_state(z, NR_FREE_CMA_PAGES);
>>  #endif
>>
>> --
>> 1.9.1
>>
>
> --
> Michal Hocko
> SUSE Labs