1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_PAGE_COUNTER_H
3 #define _LINUX_PAGE_COUNTER_H
4 
5 #include <linux/atomic.h>
6 #include <linux/kernel.h>
7 #include <asm/page.h>
8 
9 struct page_counter {
10 	atomic_long_t usage;
11 	unsigned long min;
12 	unsigned long low;
13 	unsigned long max;
14 	struct page_counter *parent;
15 
16 	/* effective memory.min and memory.min usage tracking */
17 	unsigned long emin;
18 	atomic_long_t min_usage;
19 	atomic_long_t children_min_usage;
20 
21 	/* effective memory.low and memory.low usage tracking */
22 	unsigned long elow;
23 	atomic_long_t low_usage;
24 	atomic_long_t children_low_usage;
25 
26 	/* legacy */
27 	unsigned long watermark;
28 	unsigned long failcnt;
29 };
30 
31 #if BITS_PER_LONG == 32
32 #define PAGE_COUNTER_MAX LONG_MAX
33 #else
34 #define PAGE_COUNTER_MAX (LONG_MAX / PAGE_SIZE)
35 #endif
36 
page_counter_init(struct page_counter * counter,struct page_counter * parent)37 static inline void page_counter_init(struct page_counter *counter,
38 				     struct page_counter *parent)
39 {
40 	atomic_long_set(&counter->usage, 0);
41 	counter->max = PAGE_COUNTER_MAX;
42 	counter->parent = parent;
43 }
44 
page_counter_read(struct page_counter * counter)45 static inline unsigned long page_counter_read(struct page_counter *counter)
46 {
47 	return atomic_long_read(&counter->usage);
48 }
49 
50 void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages);
51 void page_counter_charge(struct page_counter *counter, unsigned long nr_pages);
52 bool page_counter_try_charge(struct page_counter *counter,
53 			     unsigned long nr_pages,
54 			     struct page_counter **fail);
55 void page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages);
56 void page_counter_set_min(struct page_counter *counter, unsigned long nr_pages);
57 void page_counter_set_low(struct page_counter *counter, unsigned long nr_pages);
58 int page_counter_set_max(struct page_counter *counter, unsigned long nr_pages);
59 int page_counter_memparse(const char *buf, const char *max,
60 			  unsigned long *nr_pages);
61 
page_counter_reset_watermark(struct page_counter * counter)62 static inline void page_counter_reset_watermark(struct page_counter *counter)
63 {
64 	counter->watermark = page_counter_read(counter);
65 }
66 
67 #endif /* _LINUX_PAGE_COUNTER_H */
68