[176/200] kernel/power: allow hibernation with page_poison sanity checking

Commit Message

Andrew Morton Dec. 15, 2020, 3:13 a.m. UTC

From: Vlastimil Babka <[e-mail]>
Subject: kernel/power: allow hibernation with page_poison sanity checking

Page poisoning used to be incompatible with hibernation, as the state of
poisoned pages was lost after resume, thus enabling CONFIG_HIBERNATION
forces CONFIG_PAGE_POISONING_NO_SANITY.  For the same reason, the
poisoning with zeroes variant CONFIG_PAGE_POISONING_ZERO used to disable
hibernation.  The latter restriction was removed by commit 1ad1410f632d
("PM / Hibernate: allow hibernation with PAGE_POISONING_ZERO") and
similarly for init_on_free by commit 18451f9f9e58 ("PM: hibernate: fix
crashes with init_on_free=1") by making sure free pages are cleared after
resume.

We can use the same mechanism to instead poison free pages with
PAGE_POISON after resume.  This covers both zero and 0xAA patterns.  Thus
we can remove the Kconfig restriction that disables page poison sanity
checking when hibernation is enabled.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Vlastimil Babka <[e-mail]>
Acked-by: Rafael J. Wysocki <[e-mail]>	[hibernation]
Reviewed-by: David Hildenbrand <[e-mail]>
Cc: Mike Rapoport <[e-mail]>
Cc: Alexander Potapenko <[e-mail]>
Cc: Kees Cook <[e-mail]>
Cc: Laura Abbott <[e-mail]>
Cc: Mateusz Nosek <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 include/linux/mm.h       |    1 +
 kernel/power/hibernate.c |    2 +-
 kernel/power/power.h     |    2 +-
 kernel/power/snapshot.c  |   14 +++++++++++---
 mm/Kconfig.debug         |    1 -
 5 files changed, 14 insertions(+), 6 deletions(-)

Patch

--- a/include/linux/mm.h~kernel-power-allow-hibernation-with-page_poison-sanity-checking
+++ a/include/linux/mm.h
@@ -2903,6 +2903,7 @@  static inline void kernel_unpoison_pages
 #else
 static inline bool page_poisoning_enabled(void) { return false; }
 static inline bool page_poisoning_enabled_static(void) { return false; }
+static inline void __kernel_poison_pages(struct page *page, int nunmpages) { }
 static inline void kernel_poison_pages(struct page *page, int numpages) { }
 static inline void kernel_unpoison_pages(struct page *page, int numpages) { }
 #endif
--- a/kernel/power/hibernate.c~kernel-power-allow-hibernation-with-page_poison-sanity-checking
+++ a/kernel/power/hibernate.c
@@ -326,7 +326,7 @@  static int create_image(int platform_mod
 
 	if (!in_suspend) {
 		events_check_enabled = false;
-		clear_free_pages();
+		clear_or_poison_free_pages();
 	}
 
 	platform_leave(platform_mode);
--- a/kernel/power/power.h~kernel-power-allow-hibernation-with-page_poison-sanity-checking
+++ a/kernel/power/power.h
@@ -106,7 +106,7 @@  extern int create_basic_memory_bitmaps(v
 extern void free_basic_memory_bitmaps(void);
 extern int hibernate_preallocate_memory(void);
 
-extern void clear_free_pages(void);
+extern void clear_or_poison_free_pages(void);
 
 /**
  *	Auxiliary structure used for reading the snapshot image data and
--- a/kernel/power/snapshot.c~kernel-power-allow-hibernation-with-page_poison-sanity-checking
+++ a/kernel/power/snapshot.c
@@ -1178,7 +1178,15 @@  void free_basic_memory_bitmaps(void)
 	pr_debug("Basic memory bitmaps freed\n");
 }
 
-void clear_free_pages(void)
+static void clear_or_poison_free_page(struct page *page)
+{
+	if (page_poisoning_enabled_static())
+		__kernel_poison_pages(page, 1);
+	else if (want_init_on_free())
+		clear_highpage(page);
+}
+
+void clear_or_poison_free_pages(void)
 {
 	struct memory_bitmap *bm = free_pages_map;
 	unsigned long pfn;
@@ -1186,12 +1194,12 @@  void clear_free_pages(void)
 	if (WARN_ON(!(free_pages_map)))
 		return;
 
-	if (IS_ENABLED(CONFIG_PAGE_POISONING_ZERO) || want_init_on_free()) {
+	if (page_poisoning_enabled() || want_init_on_free()) {
 		memory_bm_position_reset(bm);
 		pfn = memory_bm_next_pfn(bm);
 		while (pfn != BM_END_OF_MAP) {
 			if (pfn_valid(pfn))
-				clear_highpage(pfn_to_page(pfn));
+				clear_or_poison_free_page(pfn_to_page(pfn));
 
 			pfn = memory_bm_next_pfn(bm);
 		}
--- a/mm/Kconfig.debug~kernel-power-allow-hibernation-with-page_poison-sanity-checking
+++ a/mm/Kconfig.debug
@@ -64,7 +64,6 @@  config PAGE_OWNER
 
 config PAGE_POISONING
 	bool "Poison pages after freeing"
-	select PAGE_POISONING_NO_SANITY if HIBERNATION
 	help
 	  Fill the pages with poison patterns after free_pages() and verify
 	  the patterns before alloc_pages. The filling of the memory helps