1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/mm.h> 3 #include <linux/page-isolation.h> 4 5 unsigned int _debug_guardpage_minorder; 6 7 bool _debug_pagealloc_enabled_early __read_mostly 8 = IS_ENABLED(CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT); 9 EXPORT_SYMBOL(_debug_pagealloc_enabled_early); 10 DEFINE_STATIC_KEY_FALSE(_debug_pagealloc_enabled); 11 EXPORT_SYMBOL(_debug_pagealloc_enabled); 12 13 DEFINE_STATIC_KEY_FALSE(_debug_guardpage_enabled); 14 15 static int __init early_debug_pagealloc(char *buf) 16 { 17 return kstrtobool(buf, &_debug_pagealloc_enabled_early); 18 } 19 early_param("debug_pagealloc", early_debug_pagealloc); 20 21 static int __init debug_guardpage_minorder_setup(char *buf) 22 { 23 unsigned long res; 24 25 if (kstrtoul(buf, 10, &res) < 0 || res > MAX_ORDER / 2) { 26 pr_err("Bad debug_guardpage_minorder value\n"); 27 return 0; 28 } 29 _debug_guardpage_minorder = res; 30 pr_info("Setting debug_guardpage_minorder to %lu\n", res); 31 return 0; 32 } 33 early_param("debug_guardpage_minorder", debug_guardpage_minorder_setup); 34 35 bool __set_page_guard(struct zone *zone, struct page *page, unsigned int order, 36 int migratetype) 37 { 38 if (order >= debug_guardpage_minorder()) 39 return false; 40 41 __SetPageGuard(page); 42 INIT_LIST_HEAD(&page->buddy_list); 43 set_page_private(page, order); 44 /* Guard pages are not available for any usage */ 45 if (!is_migrate_isolate(migratetype)) 46 __mod_zone_freepage_state(zone, -(1 << order), migratetype); 47 48 return true; 49 } 50 51 void __clear_page_guard(struct zone *zone, struct page *page, unsigned int order, 52 int migratetype) 53 { 54 __ClearPageGuard(page); 55 56 set_page_private(page, 0); 57 if (!is_migrate_isolate(migratetype)) 58 __mod_zone_freepage_state(zone, (1 << order), migratetype); 59 } 60