/*
* linux/mm/vmscan.c
*
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
*
* Swap reorganised 29.12.95, Stephen Tweedie.
* kswapd added: 7.1.96 sct
* Removed kswapd_ctl limits, and swap out as many pages as needed
* to bring the system back to freepages.high: 2.4.97, Rik van Riel.
* Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com).
* Multiqueue VM started 5.8.00, Rik van Riel.
*/
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/kernel_stat.h>
#include <linux/swap.h>
#include <linux/pagemap.h>
#include <linux/init.h>
#include <linux/highmem.h>
#include <linux/file.h>
#include <linux/writeback.h>
#include <linux/blkdev.h>
#include <linux/buffer_head.h> /* for try_to_release_page(),
buffer_heads_over_limit */
#include <linux/mm_inline.h>
#include <linux/pagevec.h>
#include <linux/backing-dev.h>
#include <linux/rmap.h>
#include <linux/topology.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/notifier.h>
#include <linux/rwsem.h>
#include <asm/tlbflush.h>
#include <asm/div64.h>
#include <linux/swapops.h>
/* possible outcome of pageout() */
typedef enum {
/* failed to write page out, page is locked */
PAGE_KEEP,
/* move page to the active list, page is locked */
PAGE_ACTIVATE,
/* page has been sent to the disk successfully, page is unlocked */
PAGE_SUCCESS,
/* page is clean and locked */
PAGE_CLEAN,
} pageout_t;
struct scan_control {
/* Ask refill_inactive_zone, or shrink_cache to scan this many pages */
unsigned long nr_to_scan;
/* Incremented by the number of inactive pages that were scanned */
unsigned long nr_scanned;
/* Incremented by the number of pages reclaimed */
unsigned long nr_reclaimed;
unsigned long nr_mapped; /* From page_state */
/* How many pages shrink_cache() should reclaim */
int nr_to_reclaim;
/* Ask shrink_caches, or shrink_zone to scan at this priority */
unsigned int priority;
/* This context's GFP mask */
unsigned int gfp_mask;
int may_writepage;
/* Can pages be swapped as part of reclaim? */
int may_swap;
/* This context's SWAP_CLUSTER_MAX. If freeing memory for
* suspend, we effectively ignore SWAP_CLUSTER_MAX.
* In this context, it doesn't matter that we scan the
* whole list at once. */
int swap_cluster_max;
};
/*
* The list of shrinker callbacks used by to apply pressure to
* ageable caches.
*/
struct shrinker {
shrinker_t shrinker;
struct list_head list;
int seeks; /* seeks to recreate an obj */
long nr; /* objs pending delete */
};
#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
#ifdef ARCH_HAS_PREFETCH
