netdev - Re: [PATCH v3 07/33] nds32: MMU initialization

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Message-ID: <20171218090848.GA5823@gary-OptiPlex-3050>
Date:   Mon, 18 Dec 2017 17:08:48 +0800
From:   Guo Ren <ren_guo@...ky.com>
To:     Greentime Hu <green.hu@...il.com>
Cc:     greentime@...estech.com, linux-kernel@...r.kernel.org,
        arnd@...db.de, linux-arch@...r.kernel.org, tglx@...utronix.de,
        jason@...edaemon.net, marc.zyngier@....com, robh+dt@...nel.org,
        netdev@...r.kernel.org, deanbo422@...il.com,
        devicetree@...r.kernel.org, viro@...iv.linux.org.uk,
        dhowells@...hat.com, will.deacon@....com,
        daniel.lezcano@...aro.org, linux-serial@...r.kernel.org,
        geert.uytterhoeven@...il.com, linus.walleij@...aro.org,
        mark.rutland@....com, greg@...ah.com,
        Vincent Chen <vincentc@...estech.com>
Subject: Re: [PATCH v3 07/33] nds32: MMU initialization

Hi Greentime,

On Fri, Dec 08, 2017 at 05:11:50PM +0800, Greentime Hu wrote:
[...]
> 
> diff --git a/arch/nds32/mm/highmem.c b/arch/nds32/mm/highmem.c
[...]
> +void *kmap(struct page *page)
> +{
> +	unsigned long vaddr;
> +	might_sleep();
> +	if (!PageHighMem(page))
> +		return page_address(page);
> +	vaddr = (unsigned long)kmap_high(page);
Here should invalid the cpu_mmu_tlb's entry, Or invalid it in the
set_pte().

eg:
vaddr0 = kmap(page0)
*vaddr0 = val0 //It will cause tlb-miss, and hard-refill to MMU-tlb
kunmap(page0)
vaddr1 = kmap(page1) // Mostly vaddr1 = vaddr0
val = vaddr1; //No tlb-miss and it will get page0's val not page1, because
		last expired vaddr0's entry is left in CPU-MMU-tlb.

Best Regards
 Guo Ren