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 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
  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
  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
  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 */