diff options
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/Kconfig.debug | 5 | ||||
| -rw-r--r-- | mm/page_alloc.c | 75 |
2 files changed, 74 insertions, 6 deletions
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug index 8b1a477162d..4b2443254de 100644 --- a/mm/Kconfig.debug +++ b/mm/Kconfig.debug @@ -4,6 +4,7 @@ config DEBUG_PAGEALLOC depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC depends on !KMEMCHECK select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC + select PAGE_GUARD if ARCH_SUPPORTS_DEBUG_PAGEALLOC ---help--- Unmap pages from the kernel linear mapping after free_pages(). This results in a large slowdown, but helps to find certain types @@ -22,3 +23,7 @@ config WANT_PAGE_DEBUG_FLAGS config PAGE_POISONING bool select WANT_PAGE_DEBUG_FLAGS + +config PAGE_GUARD + bool + select WANT_PAGE_DEBUG_FLAGS diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 3cba4b67203..93baebcc06f 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -57,6 +57,7 @@ #include <linux/ftrace_event.h> #include <linux/memcontrol.h> #include <linux/prefetch.h> +#include <linux/page-debug-flags.h> #include <asm/tlbflush.h> #include <asm/div64.h> @@ -388,6 +389,37 @@ static inline void prep_zero_page(struct page *page, int order, gfp_t gfp_flags) clear_highpage(page + i); } +#ifdef CONFIG_DEBUG_PAGEALLOC +unsigned int _debug_guardpage_minorder; + +static int __init debug_guardpage_minorder_setup(char *buf) +{ + unsigned long res; + + if (kstrtoul(buf, 10, &res) < 0 || res > MAX_ORDER / 2) { + printk(KERN_ERR "Bad debug_guardpage_minorder value\n"); + return 0; + } + _debug_guardpage_minorder = res; + printk(KERN_INFO "Setting debug_guardpage_minorder to %lu\n", res); + return 0; +} +__setup("debug_guardpage_minorder=", debug_guardpage_minorder_setup); + +static inline void set_page_guard_flag(struct page *page) +{ + __set_bit(PAGE_DEBUG_FLAG_GUARD, &page->debug_flags); +} + +static inline void clear_page_guard_flag(struct page *page) +{ + __clear_bit(PAGE_DEBUG_FLAG_GUARD, &page->debug_flags); +} +#else +static inline void set_page_guard_flag(struct page *page) { } +static inline void clear_page_guard_flag(struct page *page) { } +#endif + static inline void set_page_order(struct page *page, int order) { set_page_private(page, order); @@ -445,6 +477,11 @@ static inline int page_is_buddy(struct page *page, struct page *buddy, if (page_zone_id(page) != page_zone_id(buddy)) return 0; + if (page_is_guard(buddy) && page_order(buddy) == order) { + VM_BUG_ON(page_count(buddy) != 0); + return 1; + } + if (PageBuddy(buddy) && page_order(buddy) == order) { VM_BUG_ON(page_count(buddy) != 0); return 1; @@ -501,11 +538,19 @@ static inline void __free_one_page(struct page *page, buddy = page + (buddy_idx - page_idx); if (!page_is_buddy(page, buddy, order)) break; - - /* Our buddy is free, merge with it and move up one order. */ - list_del(&buddy->lru); - zone->free_area[order].nr_free--; - rmv_page_order(buddy); + /* + * Our buddy is free or it is CONFIG_DEBUG_PAGEALLOC guard page, + * merge with it and move up one order. + */ + if (page_is_guard(buddy)) { + clear_page_guard_flag(buddy); + set_page_private(page, 0); + __mod_zone_page_state(zone, NR_FREE_PAGES, 1 << order); + } else { + list_del(&buddy->lru); + zone->free_area[order].nr_free--; + rmv_page_order(buddy); + } combined_idx = buddy_idx & page_idx; page = page + (combined_idx - page_idx); page_idx = combined_idx; @@ -731,6 +776,23 @@ static inline void expand(struct zone *zone, struct page *page, high--; size >>= 1; VM_BUG_ON(bad_range(zone, &page[size])); + +#ifdef CONFIG_DEBUG_PAGEALLOC + if (high < debug_guardpage_minorder()) { + /* + * Mark as guard pages (or page), that will allow to + * merge back to allocator when buddy will be freed. + * Corresponding page table entries will not be touched, + * pages will stay not present in virtual address space + */ + INIT_LIST_HEAD(&page[size].lru); + set_page_guard_flag(&page[size]); + set_page_private(&page[size], high); + /* Guard pages are not available for any usage */ + __mod_zone_page_state(zone, NR_FREE_PAGES, -(1 << high)); + continue; + } +#endif list_add(&page[size].lru, &area->free_list[migratetype]); area->nr_free++; set_page_order(&page[size], high); @@ -1754,7 +1816,8 @@ void warn_alloc_failed(gfp_t gfp_mask, int order, const char *fmt, ...) { unsigned int filter = SHOW_MEM_FILTER_NODES; - if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs)) + if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs) || + debug_guardpage_minorder() > 0) return; /* |