On Wed, Nov 21, 2018 at 05:12:06PM +0100, Christoph Hellwig wrote: > On Wed, Nov 21, 2018 at 11:48:13PM +0800, Ming Lei wrote: > > I guess the correct check should be: > > > > end_addr = vec_addr + bv->bv_offset + bv->bv_len; > > if (same_page && > > (end_addr & PAGE_MASK) != (page_addr & PAGE_MASK)) > > return false; > > Indeed. The above is still not totally correct, and it should have been: end_addr = vec_addr + bv->bv_offset + bv->bv_len - 1; if (same_page && (end_addr & PAGE_MASK) != page_addr) return false; Also bv->bv_len should be guaranteed as being bigger than zero. It also shows that it is quite easy to figure out the last page as wrong, :-( Thanks, Ming
