pagema-cache: Don't exceed task size on hight bound

If area is close to TASK_SIZE limit the high address
may exceed it returning error once we try to read
pagemap file. So limit the high address.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

pagemap-cache.c

@@ -66,6 +66,9 @@ static int pmc_fill_cache(pmc_t *pmc, struct vma_area *vma)
 	size_t len = vma_area_len(vma);
 	size_t size_map;
 
+	if (high > TASK_SIZE)
+		high = TASK_SIZE;
+
 	pmc->start = vma->e->start;
 	pmc->end = vma->e->end;