Re: [PATCH v2 4/4] mm/vmalloc: Hugepage vmalloc mappings

[Nicholas Piggin <npiggin@gmail.com>]

Excerpts from Zefan Li's message of July 1, 2020 5:10 pm:
>>  static void *__vmalloc_node(unsigned long size, unsigned long align,
>> -			    gfp_t gfp_mask, pgprot_t prot,
>> -			    int node, const void *caller);
>> +			gfp_t gfp_mask, pgprot_t prot, unsigned long vm_flags,
>> +			int node, const void *caller);
>>  static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
>> -				 pgprot_t prot, int node)
>> +				 pgprot_t prot, unsigned int page_shift,
>> +				 int node)
>>  {
>>  	struct page **pages;
>> +	unsigned long addr = (unsigned long)area->addr;
>> +	unsigned long size = get_vm_area_size(area);
>> +	unsigned int page_order = page_shift - PAGE_SHIFT;
>>  	unsigned int nr_pages, array_size, i;
>>  	const gfp_t nested_gfp = (gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO;
>>  	const gfp_t alloc_mask = gfp_mask | __GFP_NOWARN;
>>  	const gfp_t highmem_mask = (gfp_mask & (GFP_DMA | GFP_DMA32)) ?
>> -					0 :
>> -					__GFP_HIGHMEM;
>> +					0 : __GFP_HIGHMEM;
>>  
>> -	nr_pages = get_vm_area_size(area) >> PAGE_SHIFT;
>> +	nr_pages = size >> page_shift;
> 
> while try out this patchset, we encountered a BUG_ON in account_kernel_stack()
> in kernel/fork.c.
> 
> BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
> 
> which obviously should be updated accordingly.

Thanks for finding that. We may have to change this around a bit so 
nr_pages still appears to be in PAGE_SIZE units for anybody looking.

Thanks,
Nick