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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.

Link: http://lkml.kernel.org/r/1490358246-11001-1-git-send-email-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>
[vinmenon@codeaurora.org: resolve trivial merge conflicts.
 Remove the redundant free pages RO feature from the
 page_poison.c file which is the reason for conflicts +
 squash the addendum commit 40961ef8d65f51093bc94de110b97b590b6b9275
 ('mm-enable-page-poisoning-early-at-boot-v2')]
Git-commit: c5b7cd344fd6341e6db79e55c0f1f4d1d9c67a7e
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
Change-Id: I1bb1f99d3a2e1135131911905e0916c837ba9d8a
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
This commit is contained in:
Vinayak Menon 2017-03-31 11:13:06 +11:00
parent 2c00b603db
commit 49118fe6a3
4 changed files with 15 additions and 71 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
include/linux/mm.h
View file

@ -2306,7 +2306,6 @@ extern void copy_user_huge_page(struct page *dst, struct page *src,
#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;

9
mm/page_alloc.c
View file

@ -1397,24 +1397,21 @@ static inline int check_new_page(struct page *page)
return 0;
}
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();
}
static int prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags,
int alloc_flags)
{
int i;
bool poisoned = true;
for (i = 0; i < (1 << order); i++) {
struct page *p = page + i;
if (unlikely(check_new_page(p)))
return 1;
if (poisoned)
poisoned &= page_is_poisoned(p);
}
set_page_private(page, 0);
@ -1425,7 +1422,7 @@ static int prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags,
kernel_map_pages(page, 1 << order, 1);
kernel_poison_pages(page, 1 << order, 1);
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);

3
mm/page_ext.c
View file

@ -54,9 +54,6 @@
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

73
mm/page_poison.c
View file

@ -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)
@ -24,71 +23,23 @@ static int early_page_poison_param(char *buf)
early_param("page_poison", early_page_poison_param);
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);
__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);
__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 (!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);
mark_addr_rdonly(addr);
kunmap_atomic(addr);
}
@ -145,13 +96,13 @@ static void unpoison_page(struct page *page)
{
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(page, addr, PAGE_SIZE);
mark_addr_rdwrite(addr);
clear_page_poison(page);
kunmap_atomic(addr);
}