RDS: memory allocated must be align to 8

Fix issue in 'rds_ib_cong_recv' when accessing unaligned memory
allocated by 'rds_page_remainder_alloc' using uint64_t pointer.
Signed-off-by: NShamir Rabinovitch <shamir.rabinovitch@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/rds/page.c

@@ -135,8 +135,8 @@ int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes,
 			if (rem->r_offset != 0)
 				rds_stats_inc(s_page_remainder_hit);
 
-			rem->r_offset += bytes;
-			if (rem->r_offset == PAGE_SIZE) {
+			rem->r_offset += ALIGN(bytes, 8);
+			if (rem->r_offset >= PAGE_SIZE) {
 				__free_page(rem->r_page);
 				rem->r_page = NULL;
 			}