linux-kernel - Re: [PATCH] zsmalloc: Fix TLB coherency and build problem

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Date:	Fri, 1 Feb 2013 14:02:18 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Minchan Kim <minchan@...nel.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Matt Sealey <matt@...esi-usa.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	Dan Magenheimer <dan.magenheimer@...cle.com>,
	Konrad Rzeszutek Wilk <konrad@...nok.org>,
	Nitin Gupta <ngupta@...are.org>,
	Seth Jennings <sjenning@...ux.vnet.ibm.com>
Subject: Re: [PATCH] zsmalloc: Fix TLB coherency and build problem

On Mon, Jan 28, 2013 at 10:00:08AM +0900, Minchan Kim wrote:
> @@ -663,7 +661,7 @@ static inline void __zs_unmap_object(struct mapping_area *area,
>  
>  	flush_cache_vunmap(addr, end);
>  	unmap_kernel_range_noflush(addr, PAGE_SIZE * 2);
> -	local_flush_tlb_kernel_range(addr, end);
> +	flush_tlb_kernel_range(addr, end);

void unmap_kernel_range_noflush(unsigned long addr, unsigned long size)
{
        vunmap_page_range(addr, addr + size);
}

void unmap_kernel_range(unsigned long addr, unsigned long size)
{
        unsigned long end = addr + size;

        flush_cache_vunmap(addr, end);
        vunmap_page_range(addr, end);
        flush_tlb_kernel_range(addr, end);
}

So, given the above, what would be different between:

	unsigned long end = addr + (PAGE_SIZE * 2);

	flush_cache_vunmap(addr, end);
	unmap_kernel_range_noflush(addr, PAGE_SIZE * 2);
	flush_tlb_kernel_range(addr, end);

(which is what it becomes after your change) and

	unmap_kernel_range(addr, PAGE_SIZE * 2);

?
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