Subject: Re: [RFC][PATCH 4/6] arm, mm: Convert arm to generic tlb
From: Catalin Marinas <catalin.marinas@arm.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>, Rik van Riel <riel@redhat.com>,
        Ingo Molnar <mingo@elte.hu>, akpm@linux-foundation.org,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
        linux-mm@kvack.org, Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        David Miller <davem@davemloft.net>,
        Hugh Dickins <hugh.dickins@tiscali.co.uk>, Mel Gorman <mel@csn.ul.ie>,
        Nick Piggin <npiggin@kernel.dk>, Russell King <rmk@arm.linux.org.uk>,
        Chris Metcalf <cmetcalf@tilera.com>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>
In-Reply-To: <1299683964.2308.3075.camel@twins>
References: <20110302175928.022902359@chello.nl>
	 <20110302180259.109909335@chello.nl>
	 <AANLkTimbRS++SCcKGrUcL5xKsCO+1ygkg+83x7F+2S4i@mail.gmail.com>
	 <1299683964.2308.3075.camel@twins>
Organization: ARM Limited
Date: Wed, 09 Mar 2011 15:36:02 +0000
Message-ID: <1299684963.19820.344.camel@e102109-lin.cambridge.arm.com>
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On Wed, 2011-03-09 at 15:19 +0000, Peter Zijlstra wrote:
> On Wed, 2011-03-09 at 15:16 +0000, Catalin Marinas wrote:
> > Hi Peter,
> >
> > On 2 March 2011 17:59, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> > > --- linux-2.6.orig/arch/arm/include/asm/tlb.h
> > > +++ linux-2.6/arch/arm/include/asm/tlb.h
> > [...]
> > > +__pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte, unsigned long addr)
> > >  {
> > >        pgtable_page_dtor(pte);
> > > -       tlb_add_flush(tlb, addr);
> > >        tlb_remove_page(tlb, pte);
> > >  }
> >
> > I think we still need a tlb_track_range() call here. On the path to
> > pte_free_tlb() (for example shift_arg_pages ... free_pte_range) there
> > doesn't seem to be any code setting the tlb->start/end range. Did I
> > miss anything?
> 
> Patch 3 included:
> 
> -#define pte_free_tlb(tlb, ptep, address)                       \
> -       do {                                                    \
> -               tlb->need_flush = 1;                            \
> -               __pte_free_tlb(tlb, ptep, address);             \
> +#define pte_free_tlb(tlb, ptep, address)                                       \
> +       do {                                                                    \
> +               tlb->need_flush = 1;                                            \
> +               tlb_track_range(tlb, address, pmd_addr_end(address, TASK_SIZE));\
> +               __pte_free_tlb(tlb, ptep, address);                             \
>         } while (0)

OK, so the range is tracked. The only issue is that for platforms with a
folded pmd the range end would go to TASK_SIZE. In this case
pgd_addr_end() would make more sense (or something like
PTRS_PER_PTE*PAGE_SIZE).

-- 
Catalin


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