LXR linux/include/linux/page

   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
   9struct 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
  37static 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
  45static inline unsigned long page_counter_read(struct page_counter *counter)
  46{
  47        return atomic_long_read(&counter->usage);
  48}
  49
  50void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages);
  51void page_counter_charge(struct page_counter *counter, unsigned long nr_pages);
  52bool page_counter_try_charge(struct page_counter *counter,
  53                             unsigned long nr_pages,
  54                             struct page_counter **fail);
  55void page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages);
  56void page_counter_set_min(struct page_counter *counter, unsigned long nr_pages);
  57void page_counter_set_low(struct page_counter *counter, unsigned long nr_pages);
  58int page_counter_set_max(struct page_counter *counter, unsigned long nr_pages);
  59int page_counter_memparse(const char *buf, const char *max,
  60                          unsigned long *nr_pages);
  61
  62static 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