From: Vlastimil Babka <vbabka@xxxxxxx>
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/20201113104033.22907-4-vbabka@xxxxxxx
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> [hibernation]
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Laura Abbott <labbott@xxxxxxxxxx>
Cc: Mateusz Nosek <mateusznosek0@xxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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(-)
--- 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
_
