Date: Mon, 21 May 2012 09:47:09 +0200
From: Martin Schwidefsky <schwidefsky@de.ibm.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
        Russell King <rmk@arm.linux.org.uk>, Paul Mundt <lethal@linux-sh.org>,
        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" <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
        "linux-mm@kvack.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>, Chris Metcalf <cmetcalf@tilera.com>
Subject: Re: [RFC][PATCH 4/6] arm, mm: Convert arm to generic tlb
Message-ID: <20120521094709.6036d868@de.ibm.com>
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On Thu, 17 May 2012 18:24:44 +0200
Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:

> On Thu, 2012-05-17 at 17:00 +0100, Catalin Marinas wrote:
> 
> > BTW, looking at your tlb-unify branch, does tlb_remove_table() call
> > tlb_flush/tlb_flush_mmu before freeing the tables?  I can only see
> > tlb_remove_page() doing this. On ARM, even UP, we need the TLB flushing
> > after clearing the pmd and before freeing the pte page table (and
> > ideally doing it less often than at every pte_free_tlb() call).
> 
> No I don't think it does, so far the only archs using the RCU stuff are
> ppc,sparc and s390 and none of those needed that (Xen might join them
> soon though). But I will have to look and consider this more carefully.
> I 'lost' most of the ppc/sparc/s390 details from memory to say this with
> any certainty.
 
s390 needs a TLB flush for the pgd, pud and pmd tables. See git commit
cd94154cc6a28dd9dc271042c1a59c08d26da886 for the sad details.

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.

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