[CRIU] [PATCH 2/2] mem: Don't assume guard page is returned in procfs with new kernels

[Cyrill Gorcunov]

If the guard page is not reported in show_map_vma we should
not ajust vma address neither we should call unmap_guard_pages
in restorer.

https://github.com/xemul/criu/issues/322

Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
---
 criu/cr-restore.c | 3 ++-
 criu/proc_parse.c | 6 ++++--
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/criu/cr-restore.c b/criu/cr-restore.c
index 298fb693a09e..d44e723cc180 100644
--- a/criu/cr-restore.c
+++ b/criu/cr-restore.c
@@ -1812,7 +1812,8 @@ static int restore_task_with_children(void *_arg)
 
 	timing_stop(TIME_FORK);
 
-	if (unmap_guard_pages(current))
+	if (kdat.mm_guard_page_maps &&
+	    unmap_guard_pages(current))
 		goto err;
 
 	restore_pgid();
diff --git a/criu/proc_parse.c b/criu/proc_parse.c
index 041d4512413d..4cb4b9dbf288 100644
--- a/criu/proc_parse.c
+++ b/criu/proc_parse.c
@@ -638,8 +638,10 @@ static int vma_list_add(struct vma_area *vma_area,
 
 	/* Add a guard page only if here is enough space for it */
 	if ((vma_area->e->flags & MAP_GROWSDOWN) &&
-	    *prev_end < vma_area->e->start)
-		vma_area->e->start -= PAGE_SIZE; /* Guard page */
+	    *prev_end < vma_area->e->start) {
+		if (kdat.mm_guard_page_maps)
+			vma_area->e->start -= PAGE_SIZE; /* Guard page */
+	}
 	*prev_end = vma_area->e->end;
 
 	list_add_tail(&vma_area->list, &vma_area_list->h);
-- 
2.7.5