Re: [PATCH] mm: extend zero pages to same element pages for zram

[zhouxianrong]

right, thanks.

On 2017/2/3 23:33, Matthew Wilcox wrote:
> On Fri, Feb 03, 2017 at 04:42:27PM +0800, zhouxianrong@xxxxxxxxxx wrote:
> > +static inline void zram_fill_page_partial(char *ptr, unsigned int size,
> > +		unsigned long value)
> > +{
> > +	int i;
> > +	unsigned long *page;
> > +
> > +	if (likely(value == 0)) {
> > +		memset(ptr, 0, size);
> > +		return;
> > +	}
> > +
> > +	i = ((unsigned long)ptr) % sizeof(*page);
> > +	if (i) {
> > +		while (i < sizeof(*page)) {
> > +			*ptr++ = (value >> (i * 8)) & 0xff;
> > +			--size;
> > +			++i;
> > +		}
> > +	}
> > +
> > +	for (i = size / sizeof(*page); i > 0; --i) {
> > +		page = (unsigned long *)ptr;
> > +		*page = value;
> > +		ptr += sizeof(*page);
> > +		size -= sizeof(*page);
> > +	}
> > +
> > +	for (i = 0; i < size; ++i)
> > +		*ptr++ = (value >> (i * 8)) & 0xff;
> > +}
>
> You're assuming little-endian here.  I think you need to do a
> cpu_to_le() here, but I don't think we have a cpu_to_leul, only
> cpu_to_le64/cpu_to_le32.  So you may have some work to do ...
>
>
> .