PM / Hibernate: allow hibernation with PAGE_POISONING_ZERO
PAGE_POISONING_ZERO disables zeroing new pages on alloc, they are
poisoned (zeroed) as they become available.
In the hibernate use case, free pages will appear in the system without
being cleared, left there by the loading kernel.
This patch will make sure free pages are cleared on resume when
PAGE_POISONING_ZERO is enabled. We free the pages just after resume
because we can't do it later: going through any device resume code might
allocate some memory and invalidate the free pages bitmap.
Thus we don't need to disable hibernation when PAGE_POISONING_ZERO is
enabled.
Signed-off-by: Anisse Astier <anisse@astier.eu>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 33c79b6..b26dbc4 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -306,8 +306,10 @@
if (error)
printk(KERN_ERR "PM: Error %d creating hibernation image\n",
error);
- if (!in_suspend)
+ if (!in_suspend) {
events_check_enabled = false;
+ clear_free_pages();
+ }
platform_leave(platform_mode);
@@ -1189,22 +1191,6 @@
return 1;
}
-static int __init page_poison_nohibernate_setup(char *str)
-{
-#ifdef CONFIG_PAGE_POISONING_ZERO
- /*
- * The zeroing option for page poison skips the checks on alloc.
- * since hibernation doesn't save free pages there's no way to
- * guarantee the pages will still be zeroed.
- */
- if (!strcmp(str, "on")) {
- pr_info("Disabling hibernation due to page poisoning\n");
- return nohibernate_setup(str);
- }
-#endif
- return 1;
-}
-
__setup("noresume", noresume_setup);
__setup("resume_offset=", resume_offset_setup);
__setup("resume=", resume_setup);
@@ -1212,4 +1198,3 @@
__setup("resumewait", resumewait_setup);
__setup("resumedelay=", resumedelay_setup);
__setup("nohibernate", nohibernate_setup);
-__setup("page_poison=", page_poison_nohibernate_setup);