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    SubjectRe: [PATCH 01/25] tile: Fix __pte_free_tlb
    On 1/25/2011 12:31 PM, Peter Zijlstra wrote:
    > Tile's __pte_free_tlb() implementation makes assumptions about the
    > generic mmu_gather implementation, cure this ;-)

    I assume you will take this patch into your tree? If so:

    Acked-by: Chris Metcalf <cmetcalf@tilera.com>

    > [ Chris, from a quick look L2_USER_PGTABLE_PAGES is something like:
    > 1 << (24 - 16 + 3), which looks awefully large for an on-stack
    > array. ]

    Yes, the pte_pages[] array in this routine is 2KB currently. Currently we
    ship with 64KB pagesize, so the kernel stack has plenty of room. I do like
    that your patch removes this buffer, however, since we're currently looking
    into (re-)supporting 4KB pages, which would totally blow the kernel stack
    in this routine.

    > Cc: Chris Metcalf <cmetcalf@tilera.com>
    > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    > ---
    > arch/tile/mm/pgtable.c | 15 ++-------------
    > 1 file changed, 2 insertions(+), 13 deletions(-)
    >
    > Index: linux-2.6/arch/tile/mm/pgtable.c
    > ===================================================================
    > --- linux-2.6.orig/arch/tile/mm/pgtable.c
    > +++ linux-2.6/arch/tile/mm/pgtable.c
    > @@ -252,19 +252,8 @@ void __pte_free_tlb(struct mmu_gather *t
    > int i;
    >
    > pgtable_page_dtor(pte);
    > - tlb->need_flush = 1;
    > - if (tlb_fast_mode(tlb)) {
    > - struct page *pte_pages[L2_USER_PGTABLE_PAGES];
    > - for (i = 0; i < L2_USER_PGTABLE_PAGES; ++i)
    > - pte_pages[i] = pte + i;
    > - free_pages_and_swap_cache(pte_pages, L2_USER_PGTABLE_PAGES);
    > - return;
    > - }
    > - for (i = 0; i < L2_USER_PGTABLE_PAGES; ++i) {
    > - tlb->pages[tlb->nr++] = pte + i;
    > - if (tlb->nr >= FREE_PTE_NR)
    > - tlb_flush_mmu(tlb, 0, 0);
    > - }
    > + for (i = 0; i < L2_USER_PGTABLE_PAGES; ++i)
    > + tlb_remove_page(tlb, pte + i);
    > }
    >
    > #ifndef __tilegx__
    >
    >

    --
    Chris Metcalf, Tilera Corp.
    http://www.tilera.com



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