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mm: page_alloc: ignore init_on_free=1 for debug_pagealloc=1

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On !ARCH_SUPPORTS_DEBUG_PAGEALLOC (like ia64) debug_pagealloc=1 implies
page_poison=on:

    if (page_poisoning_enabled() ||
         (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) &&
          debug_pagealloc_enabled()))
            static_branch_enable(&_page_poisoning_enabled);

page_poison=on needs to override init_on_free=1.

Before the change it did not work as expected for the following case:
- have PAGE_POISONING=y
- have page_poison unset
- have !ARCH_SUPPORTS_DEBUG_PAGEALLOC arch (like ia64)
- have init_on_free=1
- have debug_pagealloc=1

That way we get both keys enabled:
- static_branch_enable(&init_on_free);
- static_branch_enable(&_page_poisoning_enabled);

which leads to poisoned pages returned for __GFP_ZERO pages.

After the change we execute only:
- static_branch_enable(&_page_poisoning_enabled);
  and ignore init_on_free=1.

Link: https://lkml.kernel.org/r/20210329222555.3077928-1-slyfox@gentoo.org
Link: https://lkml.org/lkml/2021/3/26/443
Fixes: 8db26a3d4735 ("mm, page_poison: use static key more efficiently")
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Sergei Trofimovich 2021-04-29 23:02:11 -07:00 committed by Linus Torvalds
parent be5dba25b4
commit 9df65f5225
1 changed files with 19 additions and 15 deletions
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34
mm/page_alloc.c
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@ -786,20 +786,7 @@ static inline void clear_page_guard(struct zone *zone, struct page *page,
*/
void init_mem_debugging_and_hardening(void)
{
if (_init_on_alloc_enabled_early) {
if (page_poisoning_enabled())
pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, "
"will take precedence over init_on_alloc\n");
else
static_branch_enable(&init_on_alloc);
}
if (_init_on_free_enabled_early) {
if (page_poisoning_enabled())
pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, "
"will take precedence over init_on_free\n");
else
static_branch_enable(&init_on_free);
}
bool page_poisoning_requested = false;
#ifdef CONFIG_PAGE_POISONING
/*
@ -808,10 +795,27 @@ void init_mem_debugging_and_hardening(void)
*/
if (page_poisoning_enabled() ||
(!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) &&
debug_pagealloc_enabled()))
debug_pagealloc_enabled())) {
static_branch_enable(&_page_poisoning_enabled);
page_poisoning_requested = true;
}
#endif
if (_init_on_alloc_enabled_early) {
if (page_poisoning_requested)
pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, "
"will take precedence over init_on_alloc\n");
else
static_branch_enable(&init_on_alloc);
}
if (_init_on_free_enabled_early) {
if (page_poisoning_requested)
pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, "
"will take precedence over init_on_free\n");
else
static_branch_enable(&init_on_free);
}
#ifdef CONFIG_DEBUG_PAGEALLOC
if (!debug_pagealloc_enabled())
return;