1// SPDX-License-Identifier: GPL-2.0
2#include <linux/mm.h>
3#include <linux/page-isolation.h>
4
5unsigned int _debug_guardpage_minorder;
6
7bool _debug_pagealloc_enabled_early __read_mostly
8 = IS_ENABLED(CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT);
9EXPORT_SYMBOL(_debug_pagealloc_enabled_early);
10DEFINE_STATIC_KEY_FALSE(_debug_pagealloc_enabled);
11EXPORT_SYMBOL(_debug_pagealloc_enabled);
12
13DEFINE_STATIC_KEY_FALSE(_debug_guardpage_enabled);
14
15static int __init early_debug_pagealloc(char *buf)
16{
17 return kstrtobool(s: buf, res: &_debug_pagealloc_enabled_early);
18}
19early_param("debug_pagealloc", early_debug_pagealloc);
20
21static int __init debug_guardpage_minorder_setup(char *buf)
22{
23 unsigned long res;
24
25 if (kstrtoul(s: buf, base: 10, res: &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}
33early_param("debug_guardpage_minorder", debug_guardpage_minorder_setup);
34
35bool __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(list: &page->buddy_list);
43 set_page_private(page, private: order);
44 /* Guard pages are not available for any usage */
45 if (!is_migrate_isolate(migratetype))
46 __mod_zone_freepage_state(zone, nr_pages: -(1 << order), migratetype);
47
48 return true;
49}
50
51void __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, private: 0);
57 if (!is_migrate_isolate(migratetype))
58 __mod_zone_freepage_state(zone, nr_pages: (1 << order), migratetype);
59}
60

source code of linux/mm/debug_page_alloc.c