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 high;
14 	unsigned long max;
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 	 * 'parent' is placed here to be far from 'usage' to reduce
32 	 * cache false sharing, as 'usage' is written mostly while
33 	 * parent is frequently read for cgroup's hierarchical
34 	 * counting nature.
35 	 */
36 	struct page_counter *parent;
37 };
38 
39 #if BITS_PER_LONG == 32
40 #define PAGE_COUNTER_MAX LONG_MAX
41 #else
42 #define PAGE_COUNTER_MAX (LONG_MAX / PAGE_SIZE)
43 #endif
44 
page_counter_init(struct page_counter * counter,struct page_counter * parent)45 static inline void page_counter_init(struct page_counter *counter,
46 				     struct page_counter *parent)
47 {
48 	atomic_long_set(&counter->usage, 0);
49 	counter->max = PAGE_COUNTER_MAX;
50 	counter->parent = parent;
51 }
52 
page_counter_read(struct page_counter * counter)53 static inline unsigned long page_counter_read(struct page_counter *counter)
54 {
55 	return atomic_long_read(&counter->usage);
56 }
57 
58 void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages);
59 void page_counter_charge(struct page_counter *counter, unsigned long nr_pages);
60 bool page_counter_try_charge(struct page_counter *counter,
61 			     unsigned long nr_pages,
62 			     struct page_counter **fail);
63 void page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages);
64 void page_counter_set_min(struct page_counter *counter, unsigned long nr_pages);
65 void page_counter_set_low(struct page_counter *counter, unsigned long nr_pages);
66 
page_counter_set_high(struct page_counter * counter,unsigned long nr_pages)67 static inline void page_counter_set_high(struct page_counter *counter,
68 					 unsigned long nr_pages)
69 {
70 	WRITE_ONCE(counter->high, nr_pages);
71 }
72 
73 int page_counter_set_max(struct page_counter *counter, unsigned long nr_pages);
74 int page_counter_memparse(const char *buf, const char *max,
75 			  unsigned long *nr_pages);
76 
page_counter_reset_watermark(struct page_counter * counter)77 static inline void page_counter_reset_watermark(struct page_counter *counter)
78 {
79 	counter->watermark = page_counter_read(counter);
80 }
81 
82 #endif /* _LINUX_PAGE_COUNTER_H */
83