Re: [PATCH 1/2] mm: hugetlb_vmemmap: fix hugetlb page number decrease failed on movable nodes

[David Hildenbrand <david@redhat.com>]

>>> releasing. With GFP_KERNEL and __GFP_THISNODE set, allocating from movable
>>> node is always failed. Fix this problem by removing __GFP_THISNODE.
>>>
>>> Signed-off-by: Yuan Can <yuancan@huawei.com>
>>> ---
>>> mm/hugetlb_vmemmap.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
>>> index c2007ef5e9b0..0485e471d224 100644
>>> --- a/mm/hugetlb_vmemmap.c
>>> +++ b/mm/hugetlb_vmemmap.c
>>> @@ -386,7 +386,7 @@ static int vmemmap_remap_free(unsigned long start, unsigned long end,
>>> static int alloc_vmemmap_page_list(unsigned long start, unsigned long end,
>>>    				   struct list_head *list)
>>> {
>>> - 	gfp_t gfp_mask = GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_THISNODE;
>>> + 	gfp_t gfp_mask = GFP_KERNEL | __GFP_RETRY_MAYFAIL;
>>
>> There is a little change for non-movable case after this change, we fist try
>> to allocate memory from the preferred node (it is same as original), if it
>> fails, it fallbacks to other nodes now. For me, it makes sense. At least, those
>> huge pages could be freed once other nodes could satisfy the allocation of
>> vmemmap pages.
>>
>> Reviewed-by: Muchun Song <songmuchun@bytedance.com>
> 
> This looks reasonable to me as well.
> 
> Cc'ing David and Michal as they are expert in hotplug.

IIUC, we still won't allocate from ZONE_MOVABLE / MIGRATE_CMA (due to 
GFP_KERNEL), so it should be fine.

-- 
Cheers,

David / dhildenb