include/linux/page_counter.h

   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         struct page_counter *parent;
  16
  17         /* effective memory.min and memory.min usage tracking */
  18         unsigned long emin;
  19         atomic_long_t min_usage;
  20         atomic_long_t children_min_usage;
  21
  22         /* effective memory.low and memory.low usage tracking */
  23         unsigned long elow;
  24         atomic_long_t low_usage;
  25         atomic_long_t children_low_usage;
  26
  27         /* legacy */
  28         unsigned long watermark;
  29         unsigned long failcnt;
  30 };
  31
  32 #if BITS_PER_LONG == 32
  33 #define PAGE_COUNTER_MAX LONG_MAX
  34 #else
  35 #define PAGE_COUNTER_MAX (LONG_MAX / PAGE_SIZE)
  36 #endif
  37
  38 static inline void page_counter_init(struct page_counter *counter,
  39                                      struct page_counter *parent)
  40 {
  41         atomic_long_set(&counter->usage, 0);
  42         counter->max = PAGE_COUNTER_MAX;
  43         counter->parent = parent;
  44 }
  45
  46 static inline unsigned long page_counter_read(struct page_counter *counter)
  47 {
  48         return atomic_long_read(&counter->usage);
  49 }
  50
  51 void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages);
  52 void page_counter_charge(struct page_counter *counter, unsigned long nr_pages);
  53 bool page_counter_try_charge(struct page_counter *counter,
  54                              unsigned long nr_pages,
  55                              struct page_counter **fail);
  56 void page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages);
  57 void page_counter_set_min(struct page_counter *counter, unsigned long nr_pages);
  58 void page_counter_set_low(struct page_counter *counter, unsigned long nr_pages);
  59
  60 static inline void page_counter_set_high(struct page_counter *counter,
  61                                          unsigned long nr_pages)
  62 {
  63         WRITE_ONCE(counter->high, nr_pages);
  64 }
  65
  66 int page_counter_set_max(struct page_counter *counter, unsigned long nr_pages);
  67 int page_counter_memparse(const char *buf, const char *max,
  68                           unsigned long *nr_pages);
  69
  70 static inline void page_counter_reset_watermark(struct page_counter *counter)
  71 {
  72         counter->watermark = page_counter_read(counter);
  73 }
  74
  75 #endif /* _LINUX_PAGE_COUNTER_H */