linux/mm/page_idle.c

// SPDX-License-Identifier: GPL-2.0
#include <linux/init.h>
#include <linux/memblock.h>
#include <linux/fs.h>
#include <linux/sysfs.h>
#include <linux/kobject.h>
#include <linux/memory_hotplug.h>
#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/pagemap.h>
#include <linux/rmap.h>
#include <linux/mmu_notifier.h>
#include <linux/page_ext.h>
#include <linux/page_idle.h>

#include "internal.h"

#define BITMAP_CHUNK_SIZE …
#define BITMAP_CHUNK_BITS …

/*
 * Idle page tracking only considers user memory pages, for other types of
 * pages the idle flag is always unset and an attempt to set it is silently
 * ignored.
 *
 * We treat a page as a user memory page if it is on an LRU list, because it is
 * always safe to pass such a page to rmap_walk(), which is essential for idle
 * page tracking. With such an indicator of user pages we can skip isolated
 * pages, but since there are not usually many of them, it will hardly affect
 * the overall result.
 *
 * This function tries to get a user memory page by pfn as described above.
 */
static struct folio *page_idle_get_folio(unsigned long pfn)
{ … }

static bool page_idle_clear_pte_refs_one(struct folio *folio,
					struct vm_area_struct *vma,
					unsigned long addr, void *arg)
{ … }

static void page_idle_clear_pte_refs(struct folio *folio)
{ … }

static ssize_t page_idle_bitmap_read(struct file *file, struct kobject *kobj,
				     struct bin_attribute *attr, char *buf,
				     loff_t pos, size_t count)
{ … }

static ssize_t page_idle_bitmap_write(struct file *file, struct kobject *kobj,
				      struct bin_attribute *attr, char *buf,
				      loff_t pos, size_t count)
{ … }

static struct bin_attribute page_idle_bitmap_attr = …;

static struct bin_attribute *page_idle_bin_attrs[] = …;

static const struct attribute_group page_idle_attr_group = …;

static int __init page_idle_init(void)
{ … }
subsys_initcall(page_idle_init);