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 max;
  12         unsigned long low;
  13         struct page_counter *parent;
  14
  15         /* effective memory.low and memory.low usage tracking */
  16         unsigned long elow;
  17         atomic_long_t low_usage;
  18         atomic_long_t children_low_usage;
  19
  20         /* legacy */
  21         unsigned long watermark;
  22         unsigned long failcnt;
  23 };
  24
  25 #if BITS_PER_LONG == 32
  26 #define PAGE_COUNTER_MAX LONG_MAX
  27 #else
  28 #define PAGE_COUNTER_MAX (LONG_MAX / PAGE_SIZE)
  29 #endif
  30
  31 static inline void page_counter_init(struct page_counter *counter,
  32                                      struct page_counter *parent)
  33 {
  34         atomic_long_set(&counter->usage, 0);
  35         counter->max = PAGE_COUNTER_MAX;
  36         counter->parent = parent;
  37 }
  38
  39 static inline unsigned long page_counter_read(struct page_counter *counter)
  40 {
  41         return atomic_long_read(&counter->usage);
  42 }
  43
  44 void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages);
  45 void page_counter_charge(struct page_counter *counter, unsigned long nr_pages);
  46 bool page_counter_try_charge(struct page_counter *counter,
  47                              unsigned long nr_pages,
  48                              struct page_counter **fail);
  49 void page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages);
  50 int page_counter_set_max(struct page_counter *counter, unsigned long nr_pages);
  51 void page_counter_set_low(struct page_counter *counter, unsigned long nr_pages);
  52 int page_counter_memparse(const char *buf, const char *max,
  53                           unsigned long *nr_pages);
  54
  55 static inline void page_counter_reset_watermark(struct page_counter *counter)
  56 {
  57         counter->watermark = page_counter_read(counter);
  58 }
  59
  60 #endif /* _LINUX_PAGE_COUNTER_H */