Messages in this thread Patch in this message | | | From | Sergei Trofimovich <> | Subject | [PATCH v2] mm: page_alloc: ignore init_on_free=1 for debug_pagealloc=1 | Date | Sat, 27 Mar 2021 18:21:44 +0000 |
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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 init_on_free=1.
Before the change id happened too late 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.
CC: Vlastimil Babka <vbabka@suse.cz> CC: Andrew Morton <akpm@linux-foundation.org> CC: linux-mm@kvack.org CC: David Hildenbrand <david@redhat.com> CC: Andrey Konovalov <andreyknvl@gmail.com> Link: https://lkml.org/lkml/2021/3/26/443 Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org> --- mm/page_alloc.c | 30 +++++++++++++++++------------- 1 file changed, 17 insertions(+), 13 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index d57d9b4f7089..10a8a1d28c11 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -764,32 +764,36 @@ static inline void clear_page_guard(struct zone *zone, struct page *page, */ void init_mem_debugging_and_hardening(void) { + bool page_poison_requested = page_poisoning_enabled(); + +#ifdef CONFIG_PAGE_POISONING + /* + * Page poisoning is debug page alloc for some arches. If + * either of those options are enabled, enable poisoning. + */ + if (page_poisoning_enabled() || + (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) && + debug_pagealloc_enabled())) { + static_branch_enable(&_page_poisoning_enabled); + page_poison_requested = true; + } +#endif + if (_init_on_alloc_enabled_early) { - if (page_poisoning_enabled()) + if (page_poison_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_enabled()) + if (page_poison_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_PAGE_POISONING - /* - * Page poisoning is debug page alloc for some arches. If - * either of those options are enabled, enable poisoning. - */ - if (page_poisoning_enabled() || - (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) && - debug_pagealloc_enabled())) - static_branch_enable(&_page_poisoning_enabled); -#endif - #ifdef CONFIG_DEBUG_PAGEALLOC if (!debug_pagealloc_enabled()) return; -- 2.31.0
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