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       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                 :       2020 :         counter->max = PAGE_COUNTER_MAX;
      42                 :       2020 :         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                 :          0 :         counter->watermark = page_counter_read(counter);
      65                 :            : }
      66                 :            : 
      67                 :            : #endif /* _LINUX_PAGE_COUNTER_H */