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    SubjectRe: [RFC][PATCH 4/6] arm, mm: Convert arm to generic tlb
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    On Thu, 2012-05-17 at 18:33 +0200, Peter Zijlstra wrote:
    > On Thu, 2012-05-17 at 18:24 +0200, Peter Zijlstra 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.
    >
    >
    > Hmm, no, thinking more that does indeed sounds strange, I'll still have
    > to consider it more carefully, but I think you might have found a bug
    > there.

    So the RCU code can from ppc in commit
    267239116987d64850ad2037d8e0f3071dc3b5ce, which has similar behaviour.
    Also I suspect the mm_users < 2 test will be incorrect for ARM since
    even the one user can be concurrent with your speculation engine.




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