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

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Message-Id: <1593735251.svr5r5cxle.astroid@bobo.none>
Date:   Fri, 03 Jul 2020 10:15:34 +1000
From:   Nicholas Piggin <npiggin@...il.com>
To:     linux-mm@...ck.org, Zefan Li <lizefan@...wei.com>
Cc:     Borislav
 Petkov <bp@...en8.de>,
        Catalin Marinas <catalin.marinas@....com>,
        "H. Peter Anvin" <hpa@...or.com>, linux-arch@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, Ingo Molnar <mingo@...hat.com>,
        Thomas
 Gleixner <tglx@...utronix.de>,
        Will Deacon <will@...nel.org>, x86@...nel.org
Subject: Re: [PATCH v2 4/4] mm/vmalloc: Hugepage vmalloc mappings

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