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    SubjectRe: [patch] cache flush bug in mm/filemap.c (all kernels >= 2.5.30(at least))
    Andrew Morton writes:

    > filemap_nopage isn't the right place to be doing these things though.
    >
    > Given that there was no page at the virtual address before filemap_nopage
    > was called I don't think any CPU cache writeback or invalidation need be
    > performed. Perhaps a writeback or invalidate is missing somewhere in the
    > unmap paths, or there is a problem in arch/arm somewhere.
    >
    > We have a no-op flush_icache_page() in do_no_page(), but I don't know what
    > that thing ever did, not what it's doing in there. (What happens if you
    > replace it with a flush_cache_page(vma, address)?)

    We used to use flush_icache_page() on ppc/ppc64 to ensure that the
    i-cache was consistent with the d-cache and with memory. It was
    needed in do_no_page for the case where the page had just been read in
    and the i-cache could have stale data reflecting the previous contents
    of the page (the i-cache doesn't snoop on ppc). But we now do that in
    update_mmu_cache.

    Paul.
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