Re: [PATCH] mm: extend prefault helpers to fault in more than PAGE_SIZE

[Hillf Danton]

On Thu, Feb 16, 2012 at 8:01 PM, Daniel Vetter <daniel.vetter@xxxxxxxx> wrote:
> @@ -416,17 +417,20 @@ static inline int fault_in_pages_writeable(char __user *uaddr, int size)
> Â Â Â Â * Writing zeroes into userspace here is OK, because we know that if
> Â Â Â Â * the zero gets there, we'll be overwriting it.
> Â Â Â Â */
> - Â Â Â ret = __put_user(0, uaddr);
> + Â Â Â while (uaddr <= end) {
> + Â Â Â Â Â Â Â ret = __put_user(0, uaddr);
> + Â Â Â Â Â Â Â if (ret != 0)
> + Â Â Â Â Â Â Â Â Â Â Â return ret;
> + Â Â Â Â Â Â Â uaddr += PAGE_SIZE;
> + Â Â Â }

What if
             uaddr & ~PAGE_MASK == PAGE_SIZE -3 &&
                end & ~PAGE_MASK == 2
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