[CRIU] [PATCH] check: Make sure dirty tracking not used on unpatched kernel

[Cyrill Gorcunov]

Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
---
 kerndat.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/kerndat.c b/kerndat.c
index 27acf0cc2ed1..04c937f1814f 100644
--- a/kerndat.c
+++ b/kerndat.c
@@ -88,6 +88,18 @@ int kerndat_get_dirty_track(void)
 
 	map[0] = '\0';
 
+	/*
+	 * It's known some kernel versions may have a dirty
+	 * page tracking bug which clears soft dirty bit if
+	 * mprotect code is unpatched. So in such case don't
+	 * allow to use dirty page tracking.
+	 */
+	if (mprotect(map, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC)) {
+		pr_perror("Alter prot err!");
+		munmap(map, PAGE_SIZE);
+		return -1;
+	}
+
 	lseek(pm2, (unsigned long)map / PAGE_SIZE * sizeof(u64), SEEK_SET);
 	ret = read(pm2, &pmap, sizeof(pmap));
 	if (ret < 0)
-- 
1.8.3.1