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/power.h b/kernel/power/power.h
index 242d8b8..56d1d0d 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -110,6 +110,8 @@
extern void free_basic_memory_bitmaps(void);
extern int hibernate_preallocate_memory(void);
+extern void clear_free_pages(void);
+
/**
* Auxiliary structure used for reading the snapshot image data and
* metadata from and writing them to the list of page backup entries