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mm: enable page poisoning early at boot

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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.

[vinmenon@codeaurora.org: fix Kconfig]
  Link: http://lkml.kernel.org/r/1490878002-14423-1-git-send-email-vinmenon@codeaurora.org
Link: http://lkml.kernel.org/r/1490358246-11001-1-git-send-email-vinmenon@codeaurora.org
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
Acked-by: Laura Abbott <labbott@redhat.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Vinayak Menon 2017-05-03 14:54:42 -07:00 committed by Linus Torvalds
parent 2872bb2d0a
commit bd33ef3681
5 changed files with 17 additions and 88 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/mm.h
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@ -2487,7 +2487,6 @@ extern long copy_huge_page_from_user(struct page *dst_page,
#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
extern struct page_ext_operations debug_guardpage_ops; extern struct page_ext_operations debug_guardpage_ops;
extern struct page_ext_operations page_poisoning_ops;
#ifdef CONFIG_DEBUG_PAGEALLOC #ifdef CONFIG_DEBUG_PAGEALLOC
extern unsigned int _debug_guardpage_minorder; extern unsigned int _debug_guardpage_minorder;

1
mm/Kconfig.debug
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@ -42,7 +42,6 @@ config DEBUG_PAGEALLOC_ENABLE_DEFAULT
config PAGE_POISONING config PAGE_POISONING
bool "Poison pages after freeing" bool "Poison pages after freeing"
select PAGE_EXTENSION
select PAGE_POISONING_NO_SANITY if HIBERNATION select PAGE_POISONING_NO_SANITY if HIBERNATION
---help--- ---help---
Fill the pages with poison patterns after free_pages() and verify Fill the pages with poison patterns after free_pages() and verify

13
mm/page_alloc.c
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@ -1689,10 +1689,10 @@ static inline int check_new_page(struct page *page)
return 1; return 1;
} }
static inline bool free_pages_prezeroed(bool poisoned) static inline bool free_pages_prezeroed(void)
{ {
return IS_ENABLED(CONFIG_PAGE_POISONING_ZERO) && return IS_ENABLED(CONFIG_PAGE_POISONING_ZERO) &&
page_poisoning_enabled() && poisoned; page_poisoning_enabled();
} }
#ifdef CONFIG_DEBUG_VM #ifdef CONFIG_DEBUG_VM
@ -1746,17 +1746,10 @@ static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags
unsigned int alloc_flags) unsigned int alloc_flags)
{ {
int i; 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); 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++) for (i = 0; i < (1 << order); i++)
clear_highpage(page + i); clear_highpage(page + i);

13
mm/page_ext.c
View File

@ -59,9 +59,6 @@
static struct page_ext_operations *page_ext_ops[] = { static struct page_ext_operations *page_ext_ops[] = {
&debug_guardpage_ops, &debug_guardpage_ops,
#ifdef CONFIG_PAGE_POISONING
&page_poisoning_ops,
#endif
#ifdef CONFIG_PAGE_OWNER #ifdef CONFIG_PAGE_OWNER
&page_owner_ops, &page_owner_ops,
#endif #endif
@ -127,15 +124,12 @@ struct page_ext *lookup_page_ext(struct page *page)
struct page_ext *base; struct page_ext *base;
base = NODE_DATA(page_to_nid(page))->node_page_ext; base = NODE_DATA(page_to_nid(page))->node_page_ext;
#if defined(CONFIG_DEBUG_VM) || defined(CONFIG_PAGE_POISONING) #if defined(CONFIG_DEBUG_VM)
/* /*
* The sanity checks the page allocator does upon freeing a * The sanity checks the page allocator does upon freeing a
* page can reach here before the page_ext arrays are * page can reach here before the page_ext arrays are
* allocated when feeding a range of pages to the allocator * allocated when feeding a range of pages to the allocator
* for the first time during bootup or memory hotplug. * for the first time during bootup or memory hotplug.
*
* This check is also necessary for ensuring page poisoning
* works as expected when enabled
*/ */
if (unlikely(!base)) if (unlikely(!base))
return NULL; return NULL;
@ -204,15 +198,12 @@ struct page_ext *lookup_page_ext(struct page *page)
{ {
unsigned long pfn = page_to_pfn(page); unsigned long pfn = page_to_pfn(page);
struct mem_section *section = __pfn_to_section(pfn); struct mem_section *section = __pfn_to_section(pfn);
#if defined(CONFIG_DEBUG_VM) || defined(CONFIG_PAGE_POISONING) #if defined(CONFIG_DEBUG_VM)
/* /*
* The sanity checks the page allocator does upon freeing a * The sanity checks the page allocator does upon freeing a
* page can reach here before the page_ext arrays are * page can reach here before the page_ext arrays are
* allocated when feeding a range of pages to the allocator * allocated when feeding a range of pages to the allocator
* for the first time during bootup or memory hotplug. * for the first time during bootup or memory hotplug.
*
* This check is also necessary for ensuring page poisoning
* works as expected when enabled
*/ */
if (!section->page_ext) if (!section->page_ext)
return NULL; return NULL;

77
mm/page_poison.c
View File

@ -6,7 +6,6 @@
#include <linux/poison.h> #include <linux/poison.h>
#include <linux/ratelimit.h> #include <linux/ratelimit.h>
static bool __page_poisoning_enabled __read_mostly;
static bool want_page_poisoning __read_mostly; static bool want_page_poisoning __read_mostly;
static int early_page_poison_param(char *buf) static int early_page_poison_param(char *buf)
@ -18,75 +17,22 @@ static int early_page_poison_param(char *buf)
early_param("page_poison", early_page_poison_param); early_param("page_poison", early_page_poison_param);
bool page_poisoning_enabled(void) 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 * Assumes that debug_pagealloc_enabled is set before
* of those options are enabled, enable poisoning * 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)) { return (want_page_poisoning ||
if (!want_page_poisoning && !debug_pagealloc_enabled()) (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) &&
return; debug_pagealloc_enabled()));
} 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);
} }
static void poison_page(struct page *page) static void poison_page(struct page *page)
{ {
void *addr = kmap_atomic(page); void *addr = kmap_atomic(page);
set_page_poison(page);
memset(addr, PAGE_POISON, PAGE_SIZE); memset(addr, PAGE_POISON, PAGE_SIZE);
kunmap_atomic(addr); kunmap_atomic(addr);
} }
@ -140,12 +86,13 @@ static void unpoison_page(struct page *page)
{ {
void *addr; void *addr;
if (!page_is_poisoned(page))
return;
addr = kmap_atomic(page); 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); check_poison_mem(addr, PAGE_SIZE);
clear_page_poison(page);
kunmap_atomic(addr); kunmap_atomic(addr);
} }