Re: copy_page() on a kmalloc-ed page with DEBUG_SLAB enabled (was "zram: do not use copy_page with non-page alinged address")

[Sergey Senozhatsky]

On (04/19/17 04:51), Matthew Wilcox 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.
> 
> Why not just use memcpy()?  Is copy_page() significantly faster than
> memcpy() for a PAGE_SIZE amount of data?

that's a good point.

I was going to ask yesterday - do we even need copy_page()? arch that
provides well optimized copy_page() quite likely provides somewhat
equally optimized memcpy(). so may be copy_page() is not even needed?

	-ss