On Thu, Dec 21, 2017 at 10:49:44AM +0800, Wei Wang wrote: > On 12/21/2017 01:10 AM, Matthew Wilcox wrote: > One more question is about the return value, why would it be ambiguous? I > think it is the same as find_next_bit() which returns the found bit or size > if not found. Because find_next_bit doesn't reasonably support a bitmap which is ULONG_MAX in size. The point of XBitmap is to support a bitmap which is ULONG_MAX in size, so every possible return value is a legitimate "we found a bit here". There's no value which can possibly be used for "no bit was found".
