The patch titled
Subject: mm: enable page poisoning early at boot
has been added to the -mm tree. Its filename is
mm-enable-page-poisoning-early-at-boot.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-enable-page-poisoning-early-at-boot.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-enable-page-poisoning-early-at-boot.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Vinayak Menon <vinmenon@xxxxxxxxxxxxxx>
Subject: mm: enable page poisoning early at boot
On SPARSEMEM systems page poisoning is enabled after buddy is up, because
of the dependency on page extension init. This causes the pages released
by free_all_bootmem not to be poisoned. This either delays or misses the
identification of some issues because the pages have to undergo another
cycle of alloc-free-alloc for any corruption to be detected. Enable page
poisoning early by getting rid of the PAGE_EXT_DEBUG_POISON flag. Since
all the free pages will now be poisoned, the flag need not be verified
before checking the poison during an alloc.
Link: http://lkml.kernel.org/r/1490358246-11001-1-git-send-email-vinmenon@xxxxxxxxxxxxxx
Signed-off-by: Vinayak Menon <vinmenon@xxxxxxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Laura Abbott <labbott@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Akinobu Mita <akinobu.mita@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm.h | 1
mm/page_alloc.c | 13 +------
mm/page_ext.c | 3 -
mm/page_poison.c | 77 ++++++-------------------------------------
4 files changed, 15 insertions(+), 79 deletions(-)
diff -puN include/linux/mm.h~mm-enable-page-poisoning-early-at-boot include/linux/mm.h
--- a/include/linux/mm.h~mm-enable-page-poisoning-early-at-boot
+++ a/include/linux/mm.h
@@ -2497,7 +2497,6 @@ extern long copy_huge_page_from_user(str
#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
extern struct page_ext_operations debug_guardpage_ops;
-extern struct page_ext_operations page_poisoning_ops;
#ifdef CONFIG_DEBUG_PAGEALLOC
extern unsigned int _debug_guardpage_minorder;
diff -puN mm/page_alloc.c~mm-enable-page-poisoning-early-at-boot mm/page_alloc.c
--- a/mm/page_alloc.c~mm-enable-page-poisoning-early-at-boot
+++ a/mm/page_alloc.c
@@ -1688,10 +1688,10 @@ static inline int check_new_page(struct
return 1;
}
-static inline bool free_pages_prezeroed(bool poisoned)
+static inline bool free_pages_prezeroed(void)
{
return IS_ENABLED(CONFIG_PAGE_POISONING_ZERO) &&
- page_poisoning_enabled() && poisoned;
+ page_poisoning_enabled();
}
#ifdef CONFIG_DEBUG_VM
@@ -1745,17 +1745,10 @@ static void prep_new_page(struct page *p
unsigned int alloc_flags)
{
int i;
- bool poisoned = true;
-
- for (i = 0; i < (1 << order); i++) {
- struct page *p = page + i;
- if (poisoned)
- poisoned &= page_is_poisoned(p);
- }
post_alloc_hook(page, order, gfp_flags);
- if (!free_pages_prezeroed(poisoned) && (gfp_flags & __GFP_ZERO))
+ if (!free_pages_prezeroed() && (gfp_flags & __GFP_ZERO))
for (i = 0; i < (1 << order); i++)
clear_highpage(page + i);
diff -puN mm/page_ext.c~mm-enable-page-poisoning-early-at-boot mm/page_ext.c
--- a/mm/page_ext.c~mm-enable-page-poisoning-early-at-boot
+++ a/mm/page_ext.c
@@ -59,9 +59,6 @@
static struct page_ext_operations *page_ext_ops[] = {
&debug_guardpage_ops,
-#ifdef CONFIG_PAGE_POISONING
- &page_poisoning_ops,
-#endif
#ifdef CONFIG_PAGE_OWNER
&page_owner_ops,
#endif
diff -puN mm/page_poison.c~mm-enable-page-poisoning-early-at-boot mm/page_poison.c
--- a/mm/page_poison.c~mm-enable-page-poisoning-early-at-boot
+++ a/mm/page_poison.c
@@ -6,7 +6,6 @@
#include <linux/poison.h>
#include <linux/ratelimit.h>
-static bool __page_poisoning_enabled __read_mostly;
static bool want_page_poisoning __read_mostly;
static int early_page_poison_param(char *buf)
@@ -19,74 +18,21 @@ early_param("page_poison", early_page_po
bool page_poisoning_enabled(void)
{
- return __page_poisoning_enabled;
-}
-
-static bool need_page_poisoning(void)
-{
- return want_page_poisoning;
-}
-
-static void init_page_poisoning(void)
-{
/*
- * page poisoning is debug page alloc for some arches. If either
- * of those options are enabled, enable poisoning
+ * Assumes that debug_pagealloc_enabled is set before
+ * free_all_bootmem.
+ * Page poisoning is debug page alloc for some arches. If
+ * either of those options are enabled, enable poisoning.
*/
- if (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC)) {
- if (!want_page_poisoning && !debug_pagealloc_enabled())
- return;
- } else {
- if (!want_page_poisoning)
- return;
- }
-
- __page_poisoning_enabled = true;
-}
-
-struct page_ext_operations page_poisoning_ops = {
- .need = need_page_poisoning,
- .init = init_page_poisoning,
-};
-
-static inline void set_page_poison(struct page *page)
-{
- struct page_ext *page_ext;
-
- page_ext = lookup_page_ext(page);
- if (unlikely(!page_ext))
- return;
-
- __set_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
-}
-
-static inline void clear_page_poison(struct page *page)
-{
- struct page_ext *page_ext;
-
- page_ext = lookup_page_ext(page);
- if (unlikely(!page_ext))
- return;
-
- __clear_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
-}
-
-bool page_is_poisoned(struct page *page)
-{
- struct page_ext *page_ext;
-
- page_ext = lookup_page_ext(page);
- if (unlikely(!page_ext))
- return false;
-
- return test_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
+ return (want_page_poisoning ||
+ (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) &&
+ debug_pagealloc_enabled()));
}
static void poison_page(struct page *page)
{
void *addr = kmap_atomic(page);
- set_page_poison(page);
memset(addr, PAGE_POISON, PAGE_SIZE);
kunmap_atomic(addr);
}
@@ -140,12 +86,13 @@ static void unpoison_page(struct page *p
{
void *addr;
- if (!page_is_poisoned(page))
- return;
-
addr = kmap_atomic(page);
+ /*
+ * Page poisoning when enabled poisons each and every page
+ * that is freed to buddy. Thus no extra check is done to
+ * see if a page was posioned.
+ */
check_poison_mem(addr, PAGE_SIZE);
- clear_page_poison(page);
kunmap_atomic(addr);
}
_
Patches currently in -mm which might be from vinmenon@xxxxxxxxxxxxxx are
mm-enable-page-poisoning-early-at-boot.patch
mm-vmscan-do-not-pass-reclaimed-slab-to-vmpressure.patch
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