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    SubjectRe: Linux-2.5.17
    On Mon, May 20, 2002 at 10:16:35PM -0700, Linus Torvalds wrote:
    > Various FS updates (including merges of quota and iget_locked), and
    > Makefile cleanups from Kai.
    > And yet more TLB shootdown stuff.

    We seem to have inconsistent cache handling in the new TLB shootdown stuff.
    Or maybe its just my misunderstanding of what's going on; whatever it is,
    the new TLB shootdown stuff appears to be quite messy.

    Lets look at the flow of the 3 places where tlb_gather_mmu is used:

    zap_page_range unmap_region exit_mmap
    flush_cache_range tlb_gather_mmu tlb_gather_mmu
    tlb_gather_mmu unmap_page_range flush_cache_mm
    unmap_page_range free_pgtables unmap_page_range
    tlb_finish_mmu tlb_finish_mmu clear_page_tables

    So we have 3 different functions, 2 different orders of gather_mmu
    and cache handling, and one with no cache handling what so ever.

    I think we have two options - either leave the cache handling up to
    tlb_start_vma() (in which case, flush_cache_range and flush_cache_mm
    are redundant and should be removed) or let it be up to the caller
    of tlb_gather_mmu to call the right cache handling function.

    I think which is actually function dependent - in zap_page_range,
    we're only removing one vma. In exit_mmap, we're removing all vmas.
    In unmap_region, we're removing an unspecified number of vmas.
    Depending on which option we choose, we'll either end up calling
    flush_cache_range() many times, or flush_cache_mm() and flushing
    the cache for a munmap of a small area.

    Russell King ( The developer of ARM Linux

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