// SPDX-License-Identifier: GPL-2.0#include <linux/mm.h>#include <linux/page-isolation.h> unsigned int _debug_guardpage_minorder; bool _debug_pagealloc_enabled_early __read_mostly			= IS_ENABLED(CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT);EXPORT_SYMBOL(_debug_pagealloc_enabled_early);DEFINE_STATIC_KEY_FALSE(_debug_pagealloc_enabled);EXPORT_SYMBOL(_debug_pagealloc_enabled); DEFINE_STATIC_KEY_FALSE(_debug_guardpage_enabled); static int __init early_debug_pagealloc(char *buf){	return kstrtobool(buf, &_debug_pagealloc_enabled_early);}early_param("debug_pagealloc", early_debug_pagealloc); static int __init debug_guardpage_minorder_setup(char *buf){	unsigned long res; 	if (kstrtoul(buf, 10, &res) < 0 ||  res > MAX_PAGE_ORDER / 2) {		pr_err("Bad debug_guardpage_minorder value\n");		return 0;	}	_debug_guardpage_minorder = res;	pr_info("Setting debug_guardpage_minorder to %lu\n", res);	return 0;}early_param("debug_guardpage_minorder", debug_guardpage_minorder_setup); bool __set_page_guard(struct zone *zone, struct page *page, unsigned int order,		      int migratetype){	if (order >= debug_guardpage_minorder())		return false; 	__SetPageGuard(page);	INIT_LIST_HEAD(&page->buddy_list);	set_page_private(page, order);	/* Guard pages are not available for any usage */	if (!is_migrate_isolate(migratetype))		__mod_zone_freepage_state(zone, -(1 << order), migratetype); 	return true;} void __clear_page_guard(struct zone *zone, struct page *page, unsigned int order,		      int migratetype){	__ClearPageGuard(page); 	set_page_private(page, 0);	if (!is_migrate_isolate(migratetype))		__mod_zone_freepage_state(zone, (1 << order), migratetype);}