From 3972f6bb1c6ae1d32dcf2e4ff635d24b77f26dcb Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Thu, 11 Jul 2019 20:55:13 -0700 Subject: [PATCH] mm, debug_pagealloc: use a page type instead of page_ext flag When debug_pagealloc is enabled, we currently allocate the page_ext array to mark guard pages with the PAGE_EXT_DEBUG_GUARD flag. Now that we have the page_type field in struct page, we can use that instead, as guard pages are neither PageSlab nor mapped to userspace. This reduces memory overhead when debug_pagealloc is enabled and there are no other features requiring the page_ext array. Link: http://lkml.kernel.org/r/20190603143451.27353-4-vbabka@suse.cz Signed-off-by: Vlastimil Babka Cc: Joonsoo Kim Cc: Matthew Wilcox Cc: "Kirill A. Shutemov" Cc: Mel Gorman Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- .../admin-guide/kernel-parameters.txt | 10 ++--- include/linux/mm.h | 10 +---- include/linux/page-flags.h | 6 +++ include/linux/page_ext.h | 1 - mm/Kconfig.debug | 1 - mm/page_alloc.c | 40 +++---------------- mm/page_ext.c | 3 -- 7 files changed, 17 insertions(+), 54 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index f1c433daef6b..aa4e7e7b87c2 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -805,12 +805,10 @@ tracking down these problems. debug_pagealloc= - [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this - parameter enables the feature at boot time. In - default, it is disabled. We can avoid allocating huge - chunk of memory for debug pagealloc if we don't enable - it at boot time and the system will work mostly same - with the kernel built without CONFIG_DEBUG_PAGEALLOC. + [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this parameter + enables the feature at boot time. By default, it is + disabled and the system will work mostly the same as a + kernel built without CONFIG_DEBUG_PAGEALLOC. on: enable the feature debugpat [X86] Enable PAT debugging diff --git a/include/linux/mm.h b/include/linux/mm.h index 2c2e98cae2d1..cb8d413d635e 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2862,8 +2862,6 @@ extern long copy_huge_page_from_user(struct page *dst_page, bool allow_pagefault); #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ -extern struct page_ext_operations debug_guardpage_ops; - #ifdef CONFIG_DEBUG_PAGEALLOC extern unsigned int _debug_guardpage_minorder; DECLARE_STATIC_KEY_FALSE(_debug_guardpage_enabled); @@ -2880,16 +2878,10 @@ static inline bool debug_guardpage_enabled(void) static inline bool page_is_guard(struct page *page) { - struct page_ext *page_ext; - if (!debug_guardpage_enabled()) return false; - page_ext = lookup_page_ext(page); - if (unlikely(!page_ext)) - return false; - - return test_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags); + return PageGuard(page); } #else static inline unsigned int debug_guardpage_minorder(void) { return 0; } diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 9f8712a4b1a5..b848517da64c 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -703,6 +703,7 @@ PAGEFLAG_FALSE(DoubleMap) #define PG_offline 0x00000100 #define PG_kmemcg 0x00000200 #define PG_table 0x00000400 +#define PG_guard 0x00000800 #define PageType(page, flag) \ ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE) @@ -754,6 +755,11 @@ PAGE_TYPE_OPS(Kmemcg, kmemcg) */ PAGE_TYPE_OPS(Table, table) +/* + * Marks guardpages used with debug_pagealloc. + */ +PAGE_TYPE_OPS(Guard, guard) + extern bool is_free_buddy_page(struct page *page); __PAGEFLAG(Isolated, isolated, PF_ANY); diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h index f84f167ec04c..09592951725c 100644 --- a/include/linux/page_ext.h +++ b/include/linux/page_ext.h @@ -17,7 +17,6 @@ struct page_ext_operations { #ifdef CONFIG_PAGE_EXTENSION enum page_ext_flags { - PAGE_EXT_DEBUG_GUARD, PAGE_EXT_OWNER, #if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT) PAGE_EXT_YOUNG, diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug index a35ab6c55192..82b6a20898bd 100644 --- a/mm/Kconfig.debug +++ b/mm/Kconfig.debug @@ -12,7 +12,6 @@ config DEBUG_PAGEALLOC bool "Debug page memory allocations" depends on DEBUG_KERNEL depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC - select PAGE_EXTENSION select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC ---help--- Unmap pages from the kernel linear mapping after free_pages(). diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 26b6ad8b065d..ae56e8feec0c 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -50,7 +50,6 @@ #include #include #include -#include #include #include #include @@ -668,18 +667,6 @@ static int __init early_debug_pagealloc(char *buf) } early_param("debug_pagealloc", early_debug_pagealloc); -static bool need_debug_guardpage(void) -{ - /* If we don't use debug_pagealloc, we don't need guard page */ - if (!debug_pagealloc_enabled()) - return false; - - if (!debug_guardpage_minorder()) - return false; - - return true; -} - static void init_debug_guardpage(void) { if (!debug_pagealloc_enabled()) @@ -691,11 +678,6 @@ static void init_debug_guardpage(void) static_branch_enable(&_debug_guardpage_enabled); } -struct page_ext_operations debug_guardpage_ops = { - .need = need_debug_guardpage, - .init = init_debug_guardpage, -}; - static int __init debug_guardpage_minorder_setup(char *buf) { unsigned long res; @@ -713,20 +695,13 @@ early_param("debug_guardpage_minorder", debug_guardpage_minorder_setup); static inline bool set_page_guard(struct zone *zone, struct page *page, unsigned int order, int migratetype) { - struct page_ext *page_ext; - if (!debug_guardpage_enabled()) return false; if (order >= debug_guardpage_minorder()) return false; - page_ext = lookup_page_ext(page); - if (unlikely(!page_ext)) - return false; - - __set_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags); - + __SetPageGuard(page); INIT_LIST_HEAD(&page->lru); set_page_private(page, order); /* Guard pages are not available for any usage */ @@ -738,23 +713,16 @@ static inline bool set_page_guard(struct zone *zone, struct page *page, static inline void clear_page_guard(struct zone *zone, struct page *page, unsigned int order, int migratetype) { - struct page_ext *page_ext; - if (!debug_guardpage_enabled()) return; - page_ext = lookup_page_ext(page); - if (unlikely(!page_ext)) - return; - - __clear_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags); + __ClearPageGuard(page); set_page_private(page, 0); if (!is_migrate_isolate(migratetype)) __mod_zone_freepage_state(zone, (1 << order), migratetype); } #else -struct page_ext_operations debug_guardpage_ops; static inline bool set_page_guard(struct zone *zone, struct page *page, unsigned int order, int migratetype) { return false; } static inline void clear_page_guard(struct zone *zone, struct page *page, @@ -1930,6 +1898,10 @@ void __init page_alloc_init_late(void) for_each_populated_zone(zone) set_zone_contiguous(zone); + +#ifdef CONFIG_DEBUG_PAGEALLOC + init_debug_guardpage(); +#endif } #ifdef CONFIG_CMA diff --git a/mm/page_ext.c b/mm/page_ext.c index d8f1aca4ad43..5f5769c7db3b 100644 --- a/mm/page_ext.c +++ b/mm/page_ext.c @@ -59,9 +59,6 @@ */ static struct page_ext_operations *page_ext_ops[] = { -#ifdef CONFIG_DEBUG_PAGEALLOC - &debug_guardpage_ops, -#endif #ifdef CONFIG_PAGE_OWNER &page_owner_ops, #endif