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

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Message-Id: <1595213278.m30kayfsvu.astroid@bobo.none>
Date:   Mon, 20 Jul 2020 12:49:02 +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 20, 2020 12:02 pm:
>> +static int vmap_pages_range_noflush(unsigned long start, unsigned long end,
>> +				    pgprot_t prot, struct page **pages,
>> +				    unsigned int page_shift)
>> +{
>> +	if (page_shift == PAGE_SIZE) {
> 
> Is this a typo of PAGE_SHIFT?

Oh good catch, yeah that'll always be going via the one-at-a-time route 
and slow down the small page vmaps. Will fix.

Thanks,
Nick

> 
>> +		return vmap_small_pages_range_noflush(start, end, prot, pages);
>> +	} else {
>> +		unsigned long addr = start;
>> +		unsigned int i, nr = (end - start) >> page_shift;
>> +
>> +		for (i = 0; i < nr; i++) {
>> +			int err;
>> +
>> +			err = vmap_range_noflush(addr,
>> +					addr + (1UL << page_shift),
>> +					__pa(page_address(pages[i])), prot,
>> +					page_shift);
>> +			if (err)
>> +				return err;
>> +
>> +			addr += 1UL << page_shift;
>> +		}
>> +
>> +		return 0;
>> +	}
>> +}
>> +
>