On 3/3/19 1:52 AM, Artemy Kovalyov wrote:
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.
OK, thanks for explaining! Artemy, while you're here, any thoughts about the
release_pages, and the change of the starting point, from the other part of the
patch:
@@ -684,9 +677,11 @@ int ib_umem_odp_map_dma_pages(struct ib_umem_odp *umem_odp,
u64 user_virt,
mutex_unlock(&umem_odp->umem_mutex);
if (ret < 0) {
- /* Release left over pages when handling errors. */
- for (++j; j < npages; ++j)
- put_page(local_page_list[j]);
+ /*
+ * Release pages, starting at the the first page
+ * that experienced an error.
+ */
+ release_pages(&local_page_list[j], npages - j);
break;
}
}
?
thanks,
--
John Hubbard
NVIDIA
