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    SubjectRe: copy_page() on a kmalloc-ed page with DEBUG_SLAB enabled (was "zram: do not use copy_page with non-page alinged address")
    On Tue 18-04-17 19:56:41, Sergey Senozhatsky wrote:
    > On (04/18/17 09:33), Michal Hocko wrote:
    > [..]
    > > > Another approach is the API does normal thing for non-aligned prefix and
    > > > tail space and fast thing for aligned space.
    > > > Otherwise, it would be happy if the API has WARN_ON non-page SIZE aligned
    > > > address.
    > >
    > > copy_page is a performance sensitive function and I believe that we do
    > > those tricks exactly for this purpose.
    >
    > a wild thought,
    >
    > use
    > #define copy_page(to,from) memcpy((to), (from), PAGE_SIZE)
    >
    > when DEBUG_SLAB is set? so arch copy_page() (if provided by arch)
    > won't be affected otherwise.

    Wouldn't this just paper over bugs? SLAB is not guaranteed to provide
    page size aligned object AFAIR.
    --
    Michal Hocko
    SUSE Labs

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