On 02/03/2019 21:44, Ira Weiny wrote:
On Sat, Mar 02, 2019 at 12:24:35PM -0800, john.hubbard@xxxxxxxxx wrote:From: John Hubbard <jhubbard@xxxxxxxxxx> ... 3. Dead code removal: the check for (user_virt & ~page_mask) is checking for a condition that can never happen, because earlier: user_virt = user_virt & page_mask; ...so, remove that entire phrase.bcnt -= min_t(size_t, npages << PAGE_SHIFT, bcnt);mutex_lock(&umem_odp->umem_mutex); for (j = 0; j < npages; j++, user_virt += PAGE_SIZE) { - if (user_virt & ~page_mask) { - p += PAGE_SIZE; - if (page_to_phys(local_page_list[j]) != p) { - ret = -EFAULT; - break; - } - put_page(local_page_list[j]); - continue; - } -I think this is trying to account for compound pages. (ie page_mask could represent more than PAGE_SIZE which is what user_virt is being incrimented by.) But putting the page in that case seems to be the wrong thing to do? Yes this was added by Artemy[1] now cc'ed.
Right, this is for huge pages, please keep it. put_page() needed to decrement refcount of the head page.
