On 25.08.2022 14:10, Juergen Gross wrote:
On 25.08.22 13:58, Jan Beulich wrote:
On 25.08.2022 13:40, Juergen Gross wrote:
--- a/drivers/xen/privcmd.c +++ b/drivers/xen/privcmd.c @@ -581,7 +581,7 @@ static int lock_pages( struct privcmd_dm_op_buf kbufs[], unsigned int num, struct page *pages[], unsigned int nr_pages, unsigned int *pinned) {
- unsigned int i;
- unsigned int i, off = 0;
for (i = 0; i < num; i++) { unsigned int requested; @@ -589,19 +589,23 @@ static int lock_pages( requested = DIV_ROUND_UP( offset_in_page(kbufs[i].uptr) + kbufs[i].size,
PAGE_SIZE);
if (requested > nr_pages) return -ENOSPC;PAGE_SIZE) - off;
page_count = pin_user_pages_fast(
(unsigned long) kbufs[i].uptr,
(unsigned long)kbufs[i].uptr + off * PAGE_SIZE, requested, FOLL_WRITE, pages);
if (page_count < 0)
return page_count;
if (page_count <= 0)
return page_count ? : -EFAULT;
*pinned += page_count; nr_pages -= page_count; pages += page_count;
off = requested - page_count;
if (off)
}i--;
Initially I thought this would go wrong only on the 3rd iteration, but meanwhile I think it's wrong already on the 2nd. What I think you need is
if (page_count < requested) i--; off += page_count;
or with the i++ from the loop header absorbed here
if (page_count == requested) i++; off += page_count;
Plus of course off needs resetting to zero whenever i advances. I.e.
if (page_count == requested) { i++; off = 0; } else { off += page_count; }
Yeah, or:
off = (page_count == requested) ? 0 : off + page_count; i += !off;
I wasn't daring to suggest something like that ;-)
Jan