--- ee7646f974a07165bd368deb3a18f6390e5553dc
+++ e4b11f18adc7d978947d4da9bb992b8cec334559
@@ -301,14 +301,16 @@ static int multipath_add_disk(mddev_t *m
 					  rdev->data_offset << 9);
 
 		/* as we don't honour merge_bvec_fn, we must never risk
-		 * violating it, so limit ->max_sector to one PAGE, as
-		 * a one page request is never in violation.
+		 * violating it, so limit ->max_phys_segments to one, lying
+		 * within a single page.
 		 * (Note: it is very unlikely that a device with
 		 * merge_bvec_fn will be involved in multipath.)
 		 */
-			if (q->merge_bvec_fn &&
-			    queue_max_sectors(q) > (PAGE_SIZE>>9))
-				blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
+			if (q->merge_bvec_fn) {
+				blk_queue_max_phys_segments(mddev->queue, 1);
+				blk_queue_segment_boundary(mddev->queue,
+							   PAGE_CACHE_SIZE - 1);
+			}
 
 			conf->working_disks++;
 			mddev->degraded--;
@@ -476,9 +478,11 @@ static int multipath_run (mddev_t *mddev
 		/* as we don't honour merge_bvec_fn, we must never risk
 		 * violating it, not that we ever expect a device with
 		 * a merge_bvec_fn to be involved in multipath */
-		if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
-		    queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9))
-			blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
+		if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
+			blk_queue_max_phys_segments(mddev->queue, 1);
+			blk_queue_segment_boundary(mddev->queue,
+						   PAGE_CACHE_SIZE - 1);
+		}
 
 		if (!test_bit(Faulty, &rdev->flags))
 			conf->working_disks++;