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

On Thu, Feb 16, 2012 at 09:32:08PM +0800, Hillf Danton wrote:

On Thu, Feb 16, 2012 at 8:01 PM, Daniel Vetter daniel.vetter@ffwll.ch wrote:

...

@@ -416,17 +417,20 @@ static inline int fault_in_pages_writeable(char __user *uaddr, int size)         * Writing zeroes into userspace here is OK, because we know that if         * the zero gets there, we'll be overwriting it.         */

• ret = __put_user(0, uaddr);

• while (uaddr <= end) {
• ret = __put_user(0, uaddr);
• if (ret != 0)
• return ret;
• uaddr += PAGE_SIZE;
• }

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

I don't quite follow - can you elaborate upon which issue you're seeing? -Daniel