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62 |
marcus.erl |
/*
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* linux/mm/vmscan.c
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3 |
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*
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* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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*
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* Swap reorganised 29.12.95, Stephen Tweedie.
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* kswapd added: 7.1.96 sct
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* Removed kswapd_ctl limits, and swap out as many pages as needed
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* to bring the system back to freepages.high: 2.4.97, Rik van Riel.
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* Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com).
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* Multiqueue VM started 5.8.00, Rik van Riel.
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*/
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#include <linux/mm.h>
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15 |
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/kernel_stat.h>
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#include <linux/swap.h>
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#include <linux/pagemap.h>
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#include <linux/init.h>
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#include <linux/highmem.h>
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#include <linux/vmstat.h>
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#include <linux/file.h>
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#include <linux/writeback.h>
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#include <linux/blkdev.h>
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#include <linux/buffer_head.h> /* for try_to_release_page(),
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buffer_heads_over_limit */
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#include <linux/mm_inline.h>
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#include <linux/pagevec.h>
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#include <linux/backing-dev.h>
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#include <linux/rmap.h>
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32 |
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#include <linux/topology.h>
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33 |
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#include <linux/cpu.h>
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34 |
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#include <linux/cpuset.h>
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#include <linux/notifier.h>
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#include <linux/rwsem.h>
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#include <linux/delay.h>
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#include <linux/kthread.h>
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#include <linux/freezer.h>
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#include <asm/tlbflush.h>
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#include <asm/div64.h>
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#include <linux/swapops.h>
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45 |
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#include "internal.h"
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47 |
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struct scan_control {
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/* Incremented by the number of inactive pages that were scanned */
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unsigned long nr_scanned;
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/* This context's GFP mask */
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gfp_t gfp_mask;
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int may_writepage;
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/* Can pages be swapped as part of reclaim? */
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int may_swap;
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/* This context's SWAP_CLUSTER_MAX. If freeing memory for
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* suspend, we effectively ignore SWAP_CLUSTER_MAX.
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* In this context, it doesn't matter that we scan the
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* whole list at once. */
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int swap_cluster_max;
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int swappiness;
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68 |
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int all_unreclaimable;
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69 |
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70 |
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int order;
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};
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#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
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#ifdef ARCH_HAS_PREFETCH
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#define prefetch_prev_lru_page(_page, _base, _field) \
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do { \
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if ((_page)->lru.prev != _base) { \
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struct page *prev; \
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\
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prev = lru_to_page(&(_page->lru)); \
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prefetch(&prev->_field); \
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} \
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} while (0)
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#else
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#define prefetch_prev_lru_page(_page, _base, _field) do { } while (0)
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#endif
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#ifdef ARCH_HAS_PREFETCHW
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#define prefetchw_prev_lru_page(_page, _base, _field) \
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do { \
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if ((_page)->lru.prev != _base) { \
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struct page *prev; \
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\
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prev = lru_to_page(&(_page->lru)); \
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prefetchw(&prev->_field); \
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} \
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} while (0)
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#else
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#define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0)
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#endif
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/*
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* From 0 .. 100. Higher means more swappy.
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*/
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int vm_swappiness = 60;
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long vm_total_pages; /* The total number of pages which the VM controls */
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109 |
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static LIST_HEAD(shrinker_list);
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static DECLARE_RWSEM(shrinker_rwsem);
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/*
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* Add a shrinker callback to be called from the vm
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*/
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void register_shrinker(struct shrinker *shrinker)
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{
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shrinker->nr = 0;
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down_write(&shrinker_rwsem);
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list_add_tail(&shrinker->list, &shrinker_list);
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up_write(&shrinker_rwsem);
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}
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EXPORT_SYMBOL(register_shrinker);
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/*
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* Remove one
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*/
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void unregister_shrinker(struct shrinker *shrinker)
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{
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129 |
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down_write(&shrinker_rwsem);
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list_del(&shrinker->list);
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up_write(&shrinker_rwsem);
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}
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EXPORT_SYMBOL(unregister_shrinker);
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#define SHRINK_BATCH 128
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/*
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* Call the shrink functions to age shrinkable caches
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*
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* Here we assume it costs one seek to replace a lru page and that it also
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* takes a seek to recreate a cache object. With this in mind we age equal
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* percentages of the lru and ageable caches. This should balance the seeks
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* generated by these structures.
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*
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* If the vm encountered mapped pages on the LRU it increase the pressure on
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* slab to avoid swapping.
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*
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* We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits.
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148 |
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*
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* `lru_pages' represents the number of on-LRU pages in all the zones which
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* are eligible for the caller's allocation attempt. It is used for balancing
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151 |
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* slab reclaim versus page reclaim.
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152 |
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*
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* Returns the number of slab objects which we shrunk.
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*/
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155 |
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unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
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unsigned long lru_pages)
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157 |
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{
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158 |
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struct shrinker *shrinker;
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unsigned long ret = 0;
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160 |
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if (scanned == 0)
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scanned = SWAP_CLUSTER_MAX;
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if (!down_read_trylock(&shrinker_rwsem))
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return 1; /* Assume we'll be able to shrink next time */
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list_for_each_entry(shrinker, &shrinker_list, list) {
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unsigned long long delta;
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unsigned long total_scan;
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unsigned long max_pass = (*shrinker->shrink)(0, gfp_mask);
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delta = (4 * scanned) / shrinker->seeks;
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delta *= max_pass;
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do_div(delta, lru_pages + 1);
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shrinker->nr += delta;
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if (shrinker->nr < 0) {
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printk(KERN_ERR "%s: nr=%ld\n",
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__FUNCTION__, shrinker->nr);
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shrinker->nr = max_pass;
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}
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/*
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* Avoid risking looping forever due to too large nr value:
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* never try to free more than twice the estimate number of
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* freeable entries.
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*/
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if (shrinker->nr > max_pass * 2)
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shrinker->nr = max_pass * 2;
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total_scan = shrinker->nr;
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shrinker->nr = 0;
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while (total_scan >= SHRINK_BATCH) {
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long this_scan = SHRINK_BATCH;
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int shrink_ret;
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int nr_before;
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nr_before = (*shrinker->shrink)(0, gfp_mask);
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shrink_ret = (*shrinker->shrink)(this_scan, gfp_mask);
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if (shrink_ret == -1)
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break;
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if (shrink_ret < nr_before)
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ret += nr_before - shrink_ret;
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count_vm_events(SLABS_SCANNED, this_scan);
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total_scan -= this_scan;
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cond_resched();
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}
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shrinker->nr += total_scan;
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}
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up_read(&shrinker_rwsem);
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return ret;
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}
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215 |
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/* Called without lock on whether page is mapped, so answer is unstable */
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static inline int page_mapping_inuse(struct page *page)
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{
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struct address_space *mapping;
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/* Page is in somebody's page tables. */
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if (page_mapped(page))
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return 1;
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225 |
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/* Be more reluctant to reclaim swapcache than pagecache */
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if (PageSwapCache(page))
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return 1;
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mapping = page_mapping(page);
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if (!mapping)
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return 0;
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233 |
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/* File is mmap'd by somebody? */
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return mapping_mapped(mapping);
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}
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static inline int is_page_cache_freeable(struct page *page)
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{
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return page_count(page) - !!PagePrivate(page) == 2;
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}
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static int may_write_to_queue(struct backing_dev_info *bdi)
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{
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if (current->flags & PF_SWAPWRITE)
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return 1;
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if (!bdi_write_congested(bdi))
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return 1;
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248 |
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if (bdi == current->backing_dev_info)
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return 1;
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250 |
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return 0;
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}
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252 |
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253 |
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/*
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254 |
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* We detected a synchronous write error writing a page out. Probably
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* -ENOSPC. We need to propagate that into the address_space for a subsequent
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256 |
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* fsync(), msync() or close().
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*
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258 |
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* The tricky part is that after writepage we cannot touch the mapping: nothing
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259 |
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* prevents it from being freed up. But we have a ref on the page and once
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260 |
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* that page is locked, the mapping is pinned.
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261 |
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*
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262 |
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* We're allowed to run sleeping lock_page() here because we know the caller has
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263 |
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* __GFP_FS.
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264 |
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*/
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265 |
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static void handle_write_error(struct address_space *mapping,
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266 |
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struct page *page, int error)
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267 |
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{
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268 |
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lock_page(page);
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if (page_mapping(page) == mapping)
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mapping_set_error(mapping, error);
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271 |
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unlock_page(page);
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}
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273 |
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274 |
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/* Request for sync pageout. */
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275 |
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enum pageout_io {
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276 |
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PAGEOUT_IO_ASYNC,
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PAGEOUT_IO_SYNC,
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};
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279 |
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280 |
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/* possible outcome of pageout() */
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281 |
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typedef enum {
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282 |
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/* failed to write page out, page is locked */
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283 |
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PAGE_KEEP,
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284 |
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/* move page to the active list, page is locked */
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285 |
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PAGE_ACTIVATE,
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/* page has been sent to the disk successfully, page is unlocked */
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287 |
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PAGE_SUCCESS,
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288 |
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/* page is clean and locked */
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289 |
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PAGE_CLEAN,
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290 |
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} pageout_t;
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291 |
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|
292 |
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/*
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293 |
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* pageout is called by shrink_page_list() for each dirty page.
|
294 |
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* Calls ->writepage().
|
295 |
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*/
|
296 |
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static pageout_t pageout(struct page *page, struct address_space *mapping,
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297 |
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enum pageout_io sync_writeback)
|
298 |
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{
|
299 |
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/*
|
300 |
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* If the page is dirty, only perform writeback if that write
|
301 |
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* will be non-blocking. To prevent this allocation from being
|
302 |
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* stalled by pagecache activity. But note that there may be
|
303 |
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* stalls if we need to run get_block(). We could test
|
304 |
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* PagePrivate for that.
|
305 |
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*
|
306 |
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* If this process is currently in generic_file_write() against
|
307 |
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* this page's queue, we can perform writeback even if that
|
308 |
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* will block.
|
309 |
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*
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310 |
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* If the page is swapcache, write it back even if that would
|
311 |
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* block, for some throttling. This happens by accident, because
|
312 |
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* swap_backing_dev_info is bust: it doesn't reflect the
|
313 |
|
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* congestion state of the swapdevs. Easy to fix, if needed.
|
314 |
|
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* See swapfile.c:page_queue_congested().
|
315 |
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*/
|
316 |
|
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if (!is_page_cache_freeable(page))
|
317 |
|
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return PAGE_KEEP;
|
318 |
|
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if (!mapping) {
|
319 |
|
|
/*
|
320 |
|
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* Some data journaling orphaned pages can have
|
321 |
|
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* page->mapping == NULL while being dirty with clean buffers.
|
322 |
|
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*/
|
323 |
|
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if (PagePrivate(page)) {
|
324 |
|
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if (try_to_free_buffers(page)) {
|
325 |
|
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ClearPageDirty(page);
|
326 |
|
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printk("%s: orphaned page\n", __FUNCTION__);
|
327 |
|
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return PAGE_CLEAN;
|
328 |
|
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}
|
329 |
|
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}
|
330 |
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return PAGE_KEEP;
|
331 |
|
|
}
|
332 |
|
|
if (mapping->a_ops->writepage == NULL)
|
333 |
|
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return PAGE_ACTIVATE;
|
334 |
|
|
if (!may_write_to_queue(mapping->backing_dev_info))
|
335 |
|
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return PAGE_KEEP;
|
336 |
|
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|
337 |
|
|
if (clear_page_dirty_for_io(page)) {
|
338 |
|
|
int res;
|
339 |
|
|
struct writeback_control wbc = {
|
340 |
|
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.sync_mode = WB_SYNC_NONE,
|
341 |
|
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.nr_to_write = SWAP_CLUSTER_MAX,
|
342 |
|
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.range_start = 0,
|
343 |
|
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.range_end = LLONG_MAX,
|
344 |
|
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.nonblocking = 1,
|
345 |
|
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.for_reclaim = 1,
|
346 |
|
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};
|
347 |
|
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|
348 |
|
|
SetPageReclaim(page);
|
349 |
|
|
res = mapping->a_ops->writepage(page, &wbc);
|
350 |
|
|
if (res < 0)
|
351 |
|
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handle_write_error(mapping, page, res);
|
352 |
|
|
if (res == AOP_WRITEPAGE_ACTIVATE) {
|
353 |
|
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ClearPageReclaim(page);
|
354 |
|
|
return PAGE_ACTIVATE;
|
355 |
|
|
}
|
356 |
|
|
|
357 |
|
|
/*
|
358 |
|
|
* Wait on writeback if requested to. This happens when
|
359 |
|
|
* direct reclaiming a large contiguous area and the
|
360 |
|
|
* first attempt to free a range of pages fails.
|
361 |
|
|
*/
|
362 |
|
|
if (PageWriteback(page) && sync_writeback == PAGEOUT_IO_SYNC)
|
363 |
|
|
wait_on_page_writeback(page);
|
364 |
|
|
|
365 |
|
|
if (!PageWriteback(page)) {
|
366 |
|
|
/* synchronous write or broken a_ops? */
|
367 |
|
|
ClearPageReclaim(page);
|
368 |
|
|
}
|
369 |
|
|
inc_zone_page_state(page, NR_VMSCAN_WRITE);
|
370 |
|
|
return PAGE_SUCCESS;
|
371 |
|
|
}
|
372 |
|
|
|
373 |
|
|
return PAGE_CLEAN;
|
374 |
|
|
}
|
375 |
|
|
|
376 |
|
|
/*
|
377 |
|
|
* Attempt to detach a locked page from its ->mapping. If it is dirty or if
|
378 |
|
|
* someone else has a ref on the page, abort and return 0. If it was
|
379 |
|
|
* successfully detached, return 1. Assumes the caller has a single ref on
|
380 |
|
|
* this page.
|
381 |
|
|
*/
|
382 |
|
|
int remove_mapping(struct address_space *mapping, struct page *page)
|
383 |
|
|
{
|
384 |
|
|
BUG_ON(!PageLocked(page));
|
385 |
|
|
BUG_ON(mapping != page_mapping(page));
|
386 |
|
|
|
387 |
|
|
write_lock_irq(&mapping->tree_lock);
|
388 |
|
|
/*
|
389 |
|
|
* The non racy check for a busy page.
|
390 |
|
|
*
|
391 |
|
|
* Must be careful with the order of the tests. When someone has
|
392 |
|
|
* a ref to the page, it may be possible that they dirty it then
|
393 |
|
|
* drop the reference. So if PageDirty is tested before page_count
|
394 |
|
|
* here, then the following race may occur:
|
395 |
|
|
*
|
396 |
|
|
* get_user_pages(&page);
|
397 |
|
|
* [user mapping goes away]
|
398 |
|
|
* write_to(page);
|
399 |
|
|
* !PageDirty(page) [good]
|
400 |
|
|
* SetPageDirty(page);
|
401 |
|
|
* put_page(page);
|
402 |
|
|
* !page_count(page) [good, discard it]
|
403 |
|
|
*
|
404 |
|
|
* [oops, our write_to data is lost]
|
405 |
|
|
*
|
406 |
|
|
* Reversing the order of the tests ensures such a situation cannot
|
407 |
|
|
* escape unnoticed. The smp_rmb is needed to ensure the page->flags
|
408 |
|
|
* load is not satisfied before that of page->_count.
|
409 |
|
|
*
|
410 |
|
|
* Note that if SetPageDirty is always performed via set_page_dirty,
|
411 |
|
|
* and thus under tree_lock, then this ordering is not required.
|
412 |
|
|
*/
|
413 |
|
|
if (unlikely(page_count(page) != 2))
|
414 |
|
|
goto cannot_free;
|
415 |
|
|
smp_rmb();
|
416 |
|
|
if (unlikely(PageDirty(page)))
|
417 |
|
|
goto cannot_free;
|
418 |
|
|
|
419 |
|
|
if (PageSwapCache(page)) {
|
420 |
|
|
swp_entry_t swap = { .val = page_private(page) };
|
421 |
|
|
__delete_from_swap_cache(page);
|
422 |
|
|
write_unlock_irq(&mapping->tree_lock);
|
423 |
|
|
swap_free(swap);
|
424 |
|
|
__put_page(page); /* The pagecache ref */
|
425 |
|
|
return 1;
|
426 |
|
|
}
|
427 |
|
|
|
428 |
|
|
__remove_from_page_cache(page);
|
429 |
|
|
write_unlock_irq(&mapping->tree_lock);
|
430 |
|
|
__put_page(page);
|
431 |
|
|
return 1;
|
432 |
|
|
|
433 |
|
|
cannot_free:
|
434 |
|
|
write_unlock_irq(&mapping->tree_lock);
|
435 |
|
|
return 0;
|
436 |
|
|
}
|
437 |
|
|
|
438 |
|
|
/*
|
439 |
|
|
* shrink_page_list() returns the number of reclaimed pages
|
440 |
|
|
*/
|
441 |
|
|
static unsigned long shrink_page_list(struct list_head *page_list,
|
442 |
|
|
struct scan_control *sc,
|
443 |
|
|
enum pageout_io sync_writeback)
|
444 |
|
|
{
|
445 |
|
|
LIST_HEAD(ret_pages);
|
446 |
|
|
struct pagevec freed_pvec;
|
447 |
|
|
int pgactivate = 0;
|
448 |
|
|
unsigned long nr_reclaimed = 0;
|
449 |
|
|
|
450 |
|
|
cond_resched();
|
451 |
|
|
|
452 |
|
|
pagevec_init(&freed_pvec, 1);
|
453 |
|
|
while (!list_empty(page_list)) {
|
454 |
|
|
struct address_space *mapping;
|
455 |
|
|
struct page *page;
|
456 |
|
|
int may_enter_fs;
|
457 |
|
|
int referenced;
|
458 |
|
|
|
459 |
|
|
cond_resched();
|
460 |
|
|
|
461 |
|
|
page = lru_to_page(page_list);
|
462 |
|
|
list_del(&page->lru);
|
463 |
|
|
|
464 |
|
|
if (TestSetPageLocked(page))
|
465 |
|
|
goto keep;
|
466 |
|
|
|
467 |
|
|
VM_BUG_ON(PageActive(page));
|
468 |
|
|
|
469 |
|
|
sc->nr_scanned++;
|
470 |
|
|
|
471 |
|
|
if (!sc->may_swap && page_mapped(page))
|
472 |
|
|
goto keep_locked;
|
473 |
|
|
|
474 |
|
|
/* Double the slab pressure for mapped and swapcache pages */
|
475 |
|
|
if (page_mapped(page) || PageSwapCache(page))
|
476 |
|
|
sc->nr_scanned++;
|
477 |
|
|
|
478 |
|
|
may_enter_fs = (sc->gfp_mask & __GFP_FS) ||
|
479 |
|
|
(PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
|
480 |
|
|
|
481 |
|
|
if (PageWriteback(page)) {
|
482 |
|
|
/*
|
483 |
|
|
* Synchronous reclaim is performed in two passes,
|
484 |
|
|
* first an asynchronous pass over the list to
|
485 |
|
|
* start parallel writeback, and a second synchronous
|
486 |
|
|
* pass to wait for the IO to complete. Wait here
|
487 |
|
|
* for any page for which writeback has already
|
488 |
|
|
* started.
|
489 |
|
|
*/
|
490 |
|
|
if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs)
|
491 |
|
|
wait_on_page_writeback(page);
|
492 |
|
|
else
|
493 |
|
|
goto keep_locked;
|
494 |
|
|
}
|
495 |
|
|
|
496 |
|
|
referenced = page_referenced(page, 1);
|
497 |
|
|
/* In active use or really unfreeable? Activate it. */
|
498 |
|
|
if (sc->order <= PAGE_ALLOC_COSTLY_ORDER &&
|
499 |
|
|
referenced && page_mapping_inuse(page))
|
500 |
|
|
goto activate_locked;
|
501 |
|
|
|
502 |
|
|
#ifdef CONFIG_SWAP
|
503 |
|
|
/*
|
504 |
|
|
* Anonymous process memory has backing store?
|
505 |
|
|
* Try to allocate it some swap space here.
|
506 |
|
|
*/
|
507 |
|
|
if (PageAnon(page) && !PageSwapCache(page))
|
508 |
|
|
if (!add_to_swap(page, GFP_ATOMIC))
|
509 |
|
|
goto activate_locked;
|
510 |
|
|
#endif /* CONFIG_SWAP */
|
511 |
|
|
|
512 |
|
|
mapping = page_mapping(page);
|
513 |
|
|
|
514 |
|
|
/*
|
515 |
|
|
* The page is mapped into the page tables of one or more
|
516 |
|
|
* processes. Try to unmap it here.
|
517 |
|
|
*/
|
518 |
|
|
if (page_mapped(page) && mapping) {
|
519 |
|
|
switch (try_to_unmap(page, 0)) {
|
520 |
|
|
case SWAP_FAIL:
|
521 |
|
|
goto activate_locked;
|
522 |
|
|
case SWAP_AGAIN:
|
523 |
|
|
goto keep_locked;
|
524 |
|
|
case SWAP_SUCCESS:
|
525 |
|
|
; /* try to free the page below */
|
526 |
|
|
}
|
527 |
|
|
}
|
528 |
|
|
|
529 |
|
|
if (PageDirty(page)) {
|
530 |
|
|
if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && referenced)
|
531 |
|
|
goto keep_locked;
|
532 |
|
|
if (!may_enter_fs)
|
533 |
|
|
goto keep_locked;
|
534 |
|
|
if (!sc->may_writepage)
|
535 |
|
|
goto keep_locked;
|
536 |
|
|
|
537 |
|
|
/* Page is dirty, try to write it out here */
|
538 |
|
|
switch (pageout(page, mapping, sync_writeback)) {
|
539 |
|
|
case PAGE_KEEP:
|
540 |
|
|
goto keep_locked;
|
541 |
|
|
case PAGE_ACTIVATE:
|
542 |
|
|
goto activate_locked;
|
543 |
|
|
case PAGE_SUCCESS:
|
544 |
|
|
if (PageWriteback(page) || PageDirty(page))
|
545 |
|
|
goto keep;
|
546 |
|
|
/*
|
547 |
|
|
* A synchronous write - probably a ramdisk. Go
|
548 |
|
|
* ahead and try to reclaim the page.
|
549 |
|
|
*/
|
550 |
|
|
if (TestSetPageLocked(page))
|
551 |
|
|
goto keep;
|
552 |
|
|
if (PageDirty(page) || PageWriteback(page))
|
553 |
|
|
goto keep_locked;
|
554 |
|
|
mapping = page_mapping(page);
|
555 |
|
|
case PAGE_CLEAN:
|
556 |
|
|
; /* try to free the page below */
|
557 |
|
|
}
|
558 |
|
|
}
|
559 |
|
|
|
560 |
|
|
/*
|
561 |
|
|
* If the page has buffers, try to free the buffer mappings
|
562 |
|
|
* associated with this page. If we succeed we try to free
|
563 |
|
|
* the page as well.
|
564 |
|
|
*
|
565 |
|
|
* We do this even if the page is PageDirty().
|
566 |
|
|
* try_to_release_page() does not perform I/O, but it is
|
567 |
|
|
* possible for a page to have PageDirty set, but it is actually
|
568 |
|
|
* clean (all its buffers are clean). This happens if the
|
569 |
|
|
* buffers were written out directly, with submit_bh(). ext3
|
570 |
|
|
* will do this, as well as the blockdev mapping.
|
571 |
|
|
* try_to_release_page() will discover that cleanness and will
|
572 |
|
|
* drop the buffers and mark the page clean - it can be freed.
|
573 |
|
|
*
|
574 |
|
|
* Rarely, pages can have buffers and no ->mapping. These are
|
575 |
|
|
* the pages which were not successfully invalidated in
|
576 |
|
|
* truncate_complete_page(). We try to drop those buffers here
|
577 |
|
|
* and if that worked, and the page is no longer mapped into
|
578 |
|
|
* process address space (page_count == 1) it can be freed.
|
579 |
|
|
* Otherwise, leave the page on the LRU so it is swappable.
|
580 |
|
|
*/
|
581 |
|
|
if (PagePrivate(page)) {
|
582 |
|
|
if (!try_to_release_page(page, sc->gfp_mask))
|
583 |
|
|
goto activate_locked;
|
584 |
|
|
if (!mapping && page_count(page) == 1)
|
585 |
|
|
goto free_it;
|
586 |
|
|
}
|
587 |
|
|
|
588 |
|
|
if (!mapping || !remove_mapping(mapping, page))
|
589 |
|
|
goto keep_locked;
|
590 |
|
|
|
591 |
|
|
free_it:
|
592 |
|
|
unlock_page(page);
|
593 |
|
|
nr_reclaimed++;
|
594 |
|
|
if (!pagevec_add(&freed_pvec, page))
|
595 |
|
|
__pagevec_release_nonlru(&freed_pvec);
|
596 |
|
|
continue;
|
597 |
|
|
|
598 |
|
|
activate_locked:
|
599 |
|
|
SetPageActive(page);
|
600 |
|
|
pgactivate++;
|
601 |
|
|
keep_locked:
|
602 |
|
|
unlock_page(page);
|
603 |
|
|
keep:
|
604 |
|
|
list_add(&page->lru, &ret_pages);
|
605 |
|
|
VM_BUG_ON(PageLRU(page));
|
606 |
|
|
}
|
607 |
|
|
list_splice(&ret_pages, page_list);
|
608 |
|
|
if (pagevec_count(&freed_pvec))
|
609 |
|
|
__pagevec_release_nonlru(&freed_pvec);
|
610 |
|
|
count_vm_events(PGACTIVATE, pgactivate);
|
611 |
|
|
return nr_reclaimed;
|
612 |
|
|
}
|
613 |
|
|
|
614 |
|
|
/* LRU Isolation modes. */
|
615 |
|
|
#define ISOLATE_INACTIVE 0 /* Isolate inactive pages. */
|
616 |
|
|
#define ISOLATE_ACTIVE 1 /* Isolate active pages. */
|
617 |
|
|
#define ISOLATE_BOTH 2 /* Isolate both active and inactive pages. */
|
618 |
|
|
|
619 |
|
|
/*
|
620 |
|
|
* Attempt to remove the specified page from its LRU. Only take this page
|
621 |
|
|
* if it is of the appropriate PageActive status. Pages which are being
|
622 |
|
|
* freed elsewhere are also ignored.
|
623 |
|
|
*
|
624 |
|
|
* page: page to consider
|
625 |
|
|
* mode: one of the LRU isolation modes defined above
|
626 |
|
|
*
|
627 |
|
|
* returns 0 on success, -ve errno on failure.
|
628 |
|
|
*/
|
629 |
|
|
static int __isolate_lru_page(struct page *page, int mode)
|
630 |
|
|
{
|
631 |
|
|
int ret = -EINVAL;
|
632 |
|
|
|
633 |
|
|
/* Only take pages on the LRU. */
|
634 |
|
|
if (!PageLRU(page))
|
635 |
|
|
return ret;
|
636 |
|
|
|
637 |
|
|
/*
|
638 |
|
|
* When checking the active state, we need to be sure we are
|
639 |
|
|
* dealing with comparible boolean values. Take the logical not
|
640 |
|
|
* of each.
|
641 |
|
|
*/
|
642 |
|
|
if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode))
|
643 |
|
|
return ret;
|
644 |
|
|
|
645 |
|
|
ret = -EBUSY;
|
646 |
|
|
if (likely(get_page_unless_zero(page))) {
|
647 |
|
|
/*
|
648 |
|
|
* Be careful not to clear PageLRU until after we're
|
649 |
|
|
* sure the page is not being freed elsewhere -- the
|
650 |
|
|
* page release code relies on it.
|
651 |
|
|
*/
|
652 |
|
|
ClearPageLRU(page);
|
653 |
|
|
ret = 0;
|
654 |
|
|
}
|
655 |
|
|
|
656 |
|
|
return ret;
|
657 |
|
|
}
|
658 |
|
|
|
659 |
|
|
/*
|
660 |
|
|
* zone->lru_lock is heavily contended. Some of the functions that
|
661 |
|
|
* shrink the lists perform better by taking out a batch of pages
|
662 |
|
|
* and working on them outside the LRU lock.
|
663 |
|
|
*
|
664 |
|
|
* For pagecache intensive workloads, this function is the hottest
|
665 |
|
|
* spot in the kernel (apart from copy_*_user functions).
|
666 |
|
|
*
|
667 |
|
|
* Appropriate locks must be held before calling this function.
|
668 |
|
|
*
|
669 |
|
|
* @nr_to_scan: The number of pages to look through on the list.
|
670 |
|
|
* @src: The LRU list to pull pages off.
|
671 |
|
|
* @dst: The temp list to put pages on to.
|
672 |
|
|
* @scanned: The number of pages that were scanned.
|
673 |
|
|
* @order: The caller's attempted allocation order
|
674 |
|
|
* @mode: One of the LRU isolation modes
|
675 |
|
|
*
|
676 |
|
|
* returns how many pages were moved onto *@dst.
|
677 |
|
|
*/
|
678 |
|
|
static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
|
679 |
|
|
struct list_head *src, struct list_head *dst,
|
680 |
|
|
unsigned long *scanned, int order, int mode)
|
681 |
|
|
{
|
682 |
|
|
unsigned long nr_taken = 0;
|
683 |
|
|
unsigned long scan;
|
684 |
|
|
|
685 |
|
|
for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) {
|
686 |
|
|
struct page *page;
|
687 |
|
|
unsigned long pfn;
|
688 |
|
|
unsigned long end_pfn;
|
689 |
|
|
unsigned long page_pfn;
|
690 |
|
|
int zone_id;
|
691 |
|
|
|
692 |
|
|
page = lru_to_page(src);
|
693 |
|
|
prefetchw_prev_lru_page(page, src, flags);
|
694 |
|
|
|
695 |
|
|
VM_BUG_ON(!PageLRU(page));
|
696 |
|
|
|
697 |
|
|
switch (__isolate_lru_page(page, mode)) {
|
698 |
|
|
case 0:
|
699 |
|
|
list_move(&page->lru, dst);
|
700 |
|
|
nr_taken++;
|
701 |
|
|
break;
|
702 |
|
|
|
703 |
|
|
case -EBUSY:
|
704 |
|
|
/* else it is being freed elsewhere */
|
705 |
|
|
list_move(&page->lru, src);
|
706 |
|
|
continue;
|
707 |
|
|
|
708 |
|
|
default:
|
709 |
|
|
BUG();
|
710 |
|
|
}
|
711 |
|
|
|
712 |
|
|
if (!order)
|
713 |
|
|
continue;
|
714 |
|
|
|
715 |
|
|
/*
|
716 |
|
|
* Attempt to take all pages in the order aligned region
|
717 |
|
|
* surrounding the tag page. Only take those pages of
|
718 |
|
|
* the same active state as that tag page. We may safely
|
719 |
|
|
* round the target page pfn down to the requested order
|
720 |
|
|
* as the mem_map is guarenteed valid out to MAX_ORDER,
|
721 |
|
|
* where that page is in a different zone we will detect
|
722 |
|
|
* it from its zone id and abort this block scan.
|
723 |
|
|
*/
|
724 |
|
|
zone_id = page_zone_id(page);
|
725 |
|
|
page_pfn = page_to_pfn(page);
|
726 |
|
|
pfn = page_pfn & ~((1 << order) - 1);
|
727 |
|
|
end_pfn = pfn + (1 << order);
|
728 |
|
|
for (; pfn < end_pfn; pfn++) {
|
729 |
|
|
struct page *cursor_page;
|
730 |
|
|
|
731 |
|
|
/* The target page is in the block, ignore it. */
|
732 |
|
|
if (unlikely(pfn == page_pfn))
|
733 |
|
|
continue;
|
734 |
|
|
|
735 |
|
|
/* Avoid holes within the zone. */
|
736 |
|
|
if (unlikely(!pfn_valid_within(pfn)))
|
737 |
|
|
break;
|
738 |
|
|
|
739 |
|
|
cursor_page = pfn_to_page(pfn);
|
740 |
|
|
/* Check that we have not crossed a zone boundary. */
|
741 |
|
|
if (unlikely(page_zone_id(cursor_page) != zone_id))
|
742 |
|
|
continue;
|
743 |
|
|
switch (__isolate_lru_page(cursor_page, mode)) {
|
744 |
|
|
case 0:
|
745 |
|
|
list_move(&cursor_page->lru, dst);
|
746 |
|
|
nr_taken++;
|
747 |
|
|
scan++;
|
748 |
|
|
break;
|
749 |
|
|
|
750 |
|
|
case -EBUSY:
|
751 |
|
|
/* else it is being freed elsewhere */
|
752 |
|
|
list_move(&cursor_page->lru, src);
|
753 |
|
|
default:
|
754 |
|
|
break;
|
755 |
|
|
}
|
756 |
|
|
}
|
757 |
|
|
}
|
758 |
|
|
|
759 |
|
|
*scanned = scan;
|
760 |
|
|
return nr_taken;
|
761 |
|
|
}
|
762 |
|
|
|
763 |
|
|
/*
|
764 |
|
|
* clear_active_flags() is a helper for shrink_active_list(), clearing
|
765 |
|
|
* any active bits from the pages in the list.
|
766 |
|
|
*/
|
767 |
|
|
static unsigned long clear_active_flags(struct list_head *page_list)
|
768 |
|
|
{
|
769 |
|
|
int nr_active = 0;
|
770 |
|
|
struct page *page;
|
771 |
|
|
|
772 |
|
|
list_for_each_entry(page, page_list, lru)
|
773 |
|
|
if (PageActive(page)) {
|
774 |
|
|
ClearPageActive(page);
|
775 |
|
|
nr_active++;
|
776 |
|
|
}
|
777 |
|
|
|
778 |
|
|
return nr_active;
|
779 |
|
|
}
|
780 |
|
|
|
781 |
|
|
/*
|
782 |
|
|
* shrink_inactive_list() is a helper for shrink_zone(). It returns the number
|
783 |
|
|
* of reclaimed pages
|
784 |
|
|
*/
|
785 |
|
|
static unsigned long shrink_inactive_list(unsigned long max_scan,
|
786 |
|
|
struct zone *zone, struct scan_control *sc)
|
787 |
|
|
{
|
788 |
|
|
LIST_HEAD(page_list);
|
789 |
|
|
struct pagevec pvec;
|
790 |
|
|
unsigned long nr_scanned = 0;
|
791 |
|
|
unsigned long nr_reclaimed = 0;
|
792 |
|
|
|
793 |
|
|
pagevec_init(&pvec, 1);
|
794 |
|
|
|
795 |
|
|
lru_add_drain();
|
796 |
|
|
spin_lock_irq(&zone->lru_lock);
|
797 |
|
|
do {
|
798 |
|
|
struct page *page;
|
799 |
|
|
unsigned long nr_taken;
|
800 |
|
|
unsigned long nr_scan;
|
801 |
|
|
unsigned long nr_freed;
|
802 |
|
|
unsigned long nr_active;
|
803 |
|
|
|
804 |
|
|
nr_taken = isolate_lru_pages(sc->swap_cluster_max,
|
805 |
|
|
&zone->inactive_list,
|
806 |
|
|
&page_list, &nr_scan, sc->order,
|
807 |
|
|
(sc->order > PAGE_ALLOC_COSTLY_ORDER)?
|
808 |
|
|
ISOLATE_BOTH : ISOLATE_INACTIVE);
|
809 |
|
|
nr_active = clear_active_flags(&page_list);
|
810 |
|
|
__count_vm_events(PGDEACTIVATE, nr_active);
|
811 |
|
|
|
812 |
|
|
__mod_zone_page_state(zone, NR_ACTIVE, -nr_active);
|
813 |
|
|
__mod_zone_page_state(zone, NR_INACTIVE,
|
814 |
|
|
-(nr_taken - nr_active));
|
815 |
|
|
zone->pages_scanned += nr_scan;
|
816 |
|
|
spin_unlock_irq(&zone->lru_lock);
|
817 |
|
|
|
818 |
|
|
nr_scanned += nr_scan;
|
819 |
|
|
nr_freed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC);
|
820 |
|
|
|
821 |
|
|
/*
|
822 |
|
|
* If we are direct reclaiming for contiguous pages and we do
|
823 |
|
|
* not reclaim everything in the list, try again and wait
|
824 |
|
|
* for IO to complete. This will stall high-order allocations
|
825 |
|
|
* but that should be acceptable to the caller
|
826 |
|
|
*/
|
827 |
|
|
if (nr_freed < nr_taken && !current_is_kswapd() &&
|
828 |
|
|
sc->order > PAGE_ALLOC_COSTLY_ORDER) {
|
829 |
|
|
congestion_wait(WRITE, HZ/10);
|
830 |
|
|
|
831 |
|
|
/*
|
832 |
|
|
* The attempt at page out may have made some
|
833 |
|
|
* of the pages active, mark them inactive again.
|
834 |
|
|
*/
|
835 |
|
|
nr_active = clear_active_flags(&page_list);
|
836 |
|
|
count_vm_events(PGDEACTIVATE, nr_active);
|
837 |
|
|
|
838 |
|
|
nr_freed += shrink_page_list(&page_list, sc,
|
839 |
|
|
PAGEOUT_IO_SYNC);
|
840 |
|
|
}
|
841 |
|
|
|
842 |
|
|
nr_reclaimed += nr_freed;
|
843 |
|
|
local_irq_disable();
|
844 |
|
|
if (current_is_kswapd()) {
|
845 |
|
|
__count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scan);
|
846 |
|
|
__count_vm_events(KSWAPD_STEAL, nr_freed);
|
847 |
|
|
} else
|
848 |
|
|
__count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scan);
|
849 |
|
|
__count_zone_vm_events(PGSTEAL, zone, nr_freed);
|
850 |
|
|
|
851 |
|
|
if (nr_taken == 0)
|
852 |
|
|
goto done;
|
853 |
|
|
|
854 |
|
|
spin_lock(&zone->lru_lock);
|
855 |
|
|
/*
|
856 |
|
|
* Put back any unfreeable pages.
|
857 |
|
|
*/
|
858 |
|
|
while (!list_empty(&page_list)) {
|
859 |
|
|
page = lru_to_page(&page_list);
|
860 |
|
|
VM_BUG_ON(PageLRU(page));
|
861 |
|
|
SetPageLRU(page);
|
862 |
|
|
list_del(&page->lru);
|
863 |
|
|
if (PageActive(page))
|
864 |
|
|
add_page_to_active_list(zone, page);
|
865 |
|
|
else
|
866 |
|
|
add_page_to_inactive_list(zone, page);
|
867 |
|
|
if (!pagevec_add(&pvec, page)) {
|
868 |
|
|
spin_unlock_irq(&zone->lru_lock);
|
869 |
|
|
__pagevec_release(&pvec);
|
870 |
|
|
spin_lock_irq(&zone->lru_lock);
|
871 |
|
|
}
|
872 |
|
|
}
|
873 |
|
|
} while (nr_scanned < max_scan);
|
874 |
|
|
spin_unlock(&zone->lru_lock);
|
875 |
|
|
done:
|
876 |
|
|
local_irq_enable();
|
877 |
|
|
pagevec_release(&pvec);
|
878 |
|
|
return nr_reclaimed;
|
879 |
|
|
}
|
880 |
|
|
|
881 |
|
|
/*
|
882 |
|
|
* We are about to scan this zone at a certain priority level. If that priority
|
883 |
|
|
* level is smaller (ie: more urgent) than the previous priority, then note
|
884 |
|
|
* that priority level within the zone. This is done so that when the next
|
885 |
|
|
* process comes in to scan this zone, it will immediately start out at this
|
886 |
|
|
* priority level rather than having to build up its own scanning priority.
|
887 |
|
|
* Here, this priority affects only the reclaim-mapped threshold.
|
888 |
|
|
*/
|
889 |
|
|
static inline void note_zone_scanning_priority(struct zone *zone, int priority)
|
890 |
|
|
{
|
891 |
|
|
if (priority < zone->prev_priority)
|
892 |
|
|
zone->prev_priority = priority;
|
893 |
|
|
}
|
894 |
|
|
|
895 |
|
|
static inline int zone_is_near_oom(struct zone *zone)
|
896 |
|
|
{
|
897 |
|
|
return zone->pages_scanned >= (zone_page_state(zone, NR_ACTIVE)
|
898 |
|
|
+ zone_page_state(zone, NR_INACTIVE))*3;
|
899 |
|
|
}
|
900 |
|
|
|
901 |
|
|
/*
|
902 |
|
|
* This moves pages from the active list to the inactive list.
|
903 |
|
|
*
|
904 |
|
|
* We move them the other way if the page is referenced by one or more
|
905 |
|
|
* processes, from rmap.
|
906 |
|
|
*
|
907 |
|
|
* If the pages are mostly unmapped, the processing is fast and it is
|
908 |
|
|
* appropriate to hold zone->lru_lock across the whole operation. But if
|
909 |
|
|
* the pages are mapped, the processing is slow (page_referenced()) so we
|
910 |
|
|
* should drop zone->lru_lock around each page. It's impossible to balance
|
911 |
|
|
* this, so instead we remove the pages from the LRU while processing them.
|
912 |
|
|
* It is safe to rely on PG_active against the non-LRU pages in here because
|
913 |
|
|
* nobody will play with that bit on a non-LRU page.
|
914 |
|
|
*
|
915 |
|
|
* The downside is that we have to touch page->_count against each page.
|
916 |
|
|
* But we had to alter page->flags anyway.
|
917 |
|
|
*/
|
918 |
|
|
static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
|
919 |
|
|
struct scan_control *sc, int priority)
|
920 |
|
|
{
|
921 |
|
|
unsigned long pgmoved;
|
922 |
|
|
int pgdeactivate = 0;
|
923 |
|
|
unsigned long pgscanned;
|
924 |
|
|
LIST_HEAD(l_hold); /* The pages which were snipped off */
|
925 |
|
|
LIST_HEAD(l_inactive); /* Pages to go onto the inactive_list */
|
926 |
|
|
LIST_HEAD(l_active); /* Pages to go onto the active_list */
|
927 |
|
|
struct page *page;
|
928 |
|
|
struct pagevec pvec;
|
929 |
|
|
int reclaim_mapped = 0;
|
930 |
|
|
|
931 |
|
|
if (sc->may_swap) {
|
932 |
|
|
long mapped_ratio;
|
933 |
|
|
long distress;
|
934 |
|
|
long swap_tendency;
|
935 |
|
|
long imbalance;
|
936 |
|
|
|
937 |
|
|
if (zone_is_near_oom(zone))
|
938 |
|
|
goto force_reclaim_mapped;
|
939 |
|
|
|
940 |
|
|
/*
|
941 |
|
|
* `distress' is a measure of how much trouble we're having
|
942 |
|
|
* reclaiming pages. 0 -> no problems. 100 -> great trouble.
|
943 |
|
|
*/
|
944 |
|
|
distress = 100 >> min(zone->prev_priority, priority);
|
945 |
|
|
|
946 |
|
|
/*
|
947 |
|
|
* The point of this algorithm is to decide when to start
|
948 |
|
|
* reclaiming mapped memory instead of just pagecache. Work out
|
949 |
|
|
* how much memory
|
950 |
|
|
* is mapped.
|
951 |
|
|
*/
|
952 |
|
|
mapped_ratio = ((global_page_state(NR_FILE_MAPPED) +
|
953 |
|
|
global_page_state(NR_ANON_PAGES)) * 100) /
|
954 |
|
|
vm_total_pages;
|
955 |
|
|
|
956 |
|
|
/*
|
957 |
|
|
* Now decide how much we really want to unmap some pages. The
|
958 |
|
|
* mapped ratio is downgraded - just because there's a lot of
|
959 |
|
|
* mapped memory doesn't necessarily mean that page reclaim
|
960 |
|
|
* isn't succeeding.
|
961 |
|
|
*
|
962 |
|
|
* The distress ratio is important - we don't want to start
|
963 |
|
|
* going oom.
|
964 |
|
|
*
|
965 |
|
|
* A 100% value of vm_swappiness overrides this algorithm
|
966 |
|
|
* altogether.
|
967 |
|
|
*/
|
968 |
|
|
swap_tendency = mapped_ratio / 2 + distress + sc->swappiness;
|
969 |
|
|
|
970 |
|
|
/*
|
971 |
|
|
* If there's huge imbalance between active and inactive
|
972 |
|
|
* (think active 100 times larger than inactive) we should
|
973 |
|
|
* become more permissive, or the system will take too much
|
974 |
|
|
* cpu before it start swapping during memory pressure.
|
975 |
|
|
* Distress is about avoiding early-oom, this is about
|
976 |
|
|
* making swappiness graceful despite setting it to low
|
977 |
|
|
* values.
|
978 |
|
|
*
|
979 |
|
|
* Avoid div by zero with nr_inactive+1, and max resulting
|
980 |
|
|
* value is vm_total_pages.
|
981 |
|
|
*/
|
982 |
|
|
imbalance = zone_page_state(zone, NR_ACTIVE);
|
983 |
|
|
imbalance /= zone_page_state(zone, NR_INACTIVE) + 1;
|
984 |
|
|
|
985 |
|
|
/*
|
986 |
|
|
* Reduce the effect of imbalance if swappiness is low,
|
987 |
|
|
* this means for a swappiness very low, the imbalance
|
988 |
|
|
* must be much higher than 100 for this logic to make
|
989 |
|
|
* the difference.
|
990 |
|
|
*
|
991 |
|
|
* Max temporary value is vm_total_pages*100.
|
992 |
|
|
*/
|
993 |
|
|
imbalance *= (vm_swappiness + 1);
|
994 |
|
|
imbalance /= 100;
|
995 |
|
|
|
996 |
|
|
/*
|
997 |
|
|
* If not much of the ram is mapped, makes the imbalance
|
998 |
|
|
* less relevant, it's high priority we refill the inactive
|
999 |
|
|
* list with mapped pages only in presence of high ratio of
|
1000 |
|
|
* mapped pages.
|
1001 |
|
|
*
|
1002 |
|
|
* Max temporary value is vm_total_pages*100.
|
1003 |
|
|
*/
|
1004 |
|
|
imbalance *= mapped_ratio;
|
1005 |
|
|
imbalance /= 100;
|
1006 |
|
|
|
1007 |
|
|
/* apply imbalance feedback to swap_tendency */
|
1008 |
|
|
swap_tendency += imbalance;
|
1009 |
|
|
|
1010 |
|
|
/*
|
1011 |
|
|
* Now use this metric to decide whether to start moving mapped
|
1012 |
|
|
* memory onto the inactive list.
|
1013 |
|
|
*/
|
1014 |
|
|
if (swap_tendency >= 100)
|
1015 |
|
|
force_reclaim_mapped:
|
1016 |
|
|
reclaim_mapped = 1;
|
1017 |
|
|
}
|
1018 |
|
|
|
1019 |
|
|
lru_add_drain();
|
1020 |
|
|
spin_lock_irq(&zone->lru_lock);
|
1021 |
|
|
pgmoved = isolate_lru_pages(nr_pages, &zone->active_list,
|
1022 |
|
|
&l_hold, &pgscanned, sc->order, ISOLATE_ACTIVE);
|
1023 |
|
|
zone->pages_scanned += pgscanned;
|
1024 |
|
|
__mod_zone_page_state(zone, NR_ACTIVE, -pgmoved);
|
1025 |
|
|
spin_unlock_irq(&zone->lru_lock);
|
1026 |
|
|
|
1027 |
|
|
while (!list_empty(&l_hold)) {
|
1028 |
|
|
cond_resched();
|
1029 |
|
|
page = lru_to_page(&l_hold);
|
1030 |
|
|
list_del(&page->lru);
|
1031 |
|
|
if (page_mapped(page)) {
|
1032 |
|
|
if (!reclaim_mapped ||
|
1033 |
|
|
(total_swap_pages == 0 && PageAnon(page)) ||
|
1034 |
|
|
page_referenced(page, 0)) {
|
1035 |
|
|
list_add(&page->lru, &l_active);
|
1036 |
|
|
continue;
|
1037 |
|
|
}
|
1038 |
|
|
}
|
1039 |
|
|
list_add(&page->lru, &l_inactive);
|
1040 |
|
|
}
|
1041 |
|
|
|
1042 |
|
|
pagevec_init(&pvec, 1);
|
1043 |
|
|
pgmoved = 0;
|
1044 |
|
|
spin_lock_irq(&zone->lru_lock);
|
1045 |
|
|
while (!list_empty(&l_inactive)) {
|
1046 |
|
|
page = lru_to_page(&l_inactive);
|
1047 |
|
|
prefetchw_prev_lru_page(page, &l_inactive, flags);
|
1048 |
|
|
VM_BUG_ON(PageLRU(page));
|
1049 |
|
|
SetPageLRU(page);
|
1050 |
|
|
VM_BUG_ON(!PageActive(page));
|
1051 |
|
|
ClearPageActive(page);
|
1052 |
|
|
|
1053 |
|
|
list_move(&page->lru, &zone->inactive_list);
|
1054 |
|
|
pgmoved++;
|
1055 |
|
|
if (!pagevec_add(&pvec, page)) {
|
1056 |
|
|
__mod_zone_page_state(zone, NR_INACTIVE, pgmoved);
|
1057 |
|
|
spin_unlock_irq(&zone->lru_lock);
|
1058 |
|
|
pgdeactivate += pgmoved;
|
1059 |
|
|
pgmoved = 0;
|
1060 |
|
|
if (buffer_heads_over_limit)
|
1061 |
|
|
pagevec_strip(&pvec);
|
1062 |
|
|
__pagevec_release(&pvec);
|
1063 |
|
|
spin_lock_irq(&zone->lru_lock);
|
1064 |
|
|
}
|
1065 |
|
|
}
|
1066 |
|
|
__mod_zone_page_state(zone, NR_INACTIVE, pgmoved);
|
1067 |
|
|
pgdeactivate += pgmoved;
|
1068 |
|
|
if (buffer_heads_over_limit) {
|
1069 |
|
|
spin_unlock_irq(&zone->lru_lock);
|
1070 |
|
|
pagevec_strip(&pvec);
|
1071 |
|
|
spin_lock_irq(&zone->lru_lock);
|
1072 |
|
|
}
|
1073 |
|
|
|
1074 |
|
|
pgmoved = 0;
|
1075 |
|
|
while (!list_empty(&l_active)) {
|
1076 |
|
|
page = lru_to_page(&l_active);
|
1077 |
|
|
prefetchw_prev_lru_page(page, &l_active, flags);
|
1078 |
|
|
VM_BUG_ON(PageLRU(page));
|
1079 |
|
|
SetPageLRU(page);
|
1080 |
|
|
VM_BUG_ON(!PageActive(page));
|
1081 |
|
|
list_move(&page->lru, &zone->active_list);
|
1082 |
|
|
pgmoved++;
|
1083 |
|
|
if (!pagevec_add(&pvec, page)) {
|
1084 |
|
|
__mod_zone_page_state(zone, NR_ACTIVE, pgmoved);
|
1085 |
|
|
pgmoved = 0;
|
1086 |
|
|
spin_unlock_irq(&zone->lru_lock);
|
1087 |
|
|
__pagevec_release(&pvec);
|
1088 |
|
|
spin_lock_irq(&zone->lru_lock);
|
1089 |
|
|
}
|
1090 |
|
|
}
|
1091 |
|
|
__mod_zone_page_state(zone, NR_ACTIVE, pgmoved);
|
1092 |
|
|
|
1093 |
|
|
__count_zone_vm_events(PGREFILL, zone, pgscanned);
|
1094 |
|
|
__count_vm_events(PGDEACTIVATE, pgdeactivate);
|
1095 |
|
|
spin_unlock_irq(&zone->lru_lock);
|
1096 |
|
|
|
1097 |
|
|
pagevec_release(&pvec);
|
1098 |
|
|
}
|
1099 |
|
|
|
1100 |
|
|
/*
|
1101 |
|
|
* This is a basic per-zone page freer. Used by both kswapd and direct reclaim.
|
1102 |
|
|
*/
|
1103 |
|
|
static unsigned long shrink_zone(int priority, struct zone *zone,
|
1104 |
|
|
struct scan_control *sc)
|
1105 |
|
|
{
|
1106 |
|
|
unsigned long nr_active;
|
1107 |
|
|
unsigned long nr_inactive;
|
1108 |
|
|
unsigned long nr_to_scan;
|
1109 |
|
|
unsigned long nr_reclaimed = 0;
|
1110 |
|
|
|
1111 |
|
|
/*
|
1112 |
|
|
* Add one to `nr_to_scan' just to make sure that the kernel will
|
1113 |
|
|
* slowly sift through the active list.
|
1114 |
|
|
*/
|
1115 |
|
|
zone->nr_scan_active +=
|
1116 |
|
|
(zone_page_state(zone, NR_ACTIVE) >> priority) + 1;
|
1117 |
|
|
nr_active = zone->nr_scan_active;
|
1118 |
|
|
if (nr_active >= sc->swap_cluster_max)
|
1119 |
|
|
zone->nr_scan_active = 0;
|
1120 |
|
|
else
|
1121 |
|
|
nr_active = 0;
|
1122 |
|
|
|
1123 |
|
|
zone->nr_scan_inactive +=
|
1124 |
|
|
(zone_page_state(zone, NR_INACTIVE) >> priority) + 1;
|
1125 |
|
|
nr_inactive = zone->nr_scan_inactive;
|
1126 |
|
|
if (nr_inactive >= sc->swap_cluster_max)
|
1127 |
|
|
zone->nr_scan_inactive = 0;
|
1128 |
|
|
else
|
1129 |
|
|
nr_inactive = 0;
|
1130 |
|
|
|
1131 |
|
|
while (nr_active || nr_inactive) {
|
1132 |
|
|
if (nr_active) {
|
1133 |
|
|
nr_to_scan = min(nr_active,
|
1134 |
|
|
(unsigned long)sc->swap_cluster_max);
|
1135 |
|
|
nr_active -= nr_to_scan;
|
1136 |
|
|
shrink_active_list(nr_to_scan, zone, sc, priority);
|
1137 |
|
|
}
|
1138 |
|
|
|
1139 |
|
|
if (nr_inactive) {
|
1140 |
|
|
nr_to_scan = min(nr_inactive,
|
1141 |
|
|
(unsigned long)sc->swap_cluster_max);
|
1142 |
|
|
nr_inactive -= nr_to_scan;
|
1143 |
|
|
nr_reclaimed += shrink_inactive_list(nr_to_scan, zone,
|
1144 |
|
|
sc);
|
1145 |
|
|
}
|
1146 |
|
|
}
|
1147 |
|
|
|
1148 |
|
|
throttle_vm_writeout(sc->gfp_mask);
|
1149 |
|
|
return nr_reclaimed;
|
1150 |
|
|
}
|
1151 |
|
|
|
1152 |
|
|
/*
|
1153 |
|
|
* This is the direct reclaim path, for page-allocating processes. We only
|
1154 |
|
|
* try to reclaim pages from zones which will satisfy the caller's allocation
|
1155 |
|
|
* request.
|
1156 |
|
|
*
|
1157 |
|
|
* We reclaim from a zone even if that zone is over pages_high. Because:
|
1158 |
|
|
* a) The caller may be trying to free *extra* pages to satisfy a higher-order
|
1159 |
|
|
* allocation or
|
1160 |
|
|
* b) The zones may be over pages_high but they must go *over* pages_high to
|
1161 |
|
|
* satisfy the `incremental min' zone defense algorithm.
|
1162 |
|
|
*
|
1163 |
|
|
* Returns the number of reclaimed pages.
|
1164 |
|
|
*
|
1165 |
|
|
* If a zone is deemed to be full of pinned pages then just give it a light
|
1166 |
|
|
* scan then give up on it.
|
1167 |
|
|
*/
|
1168 |
|
|
static unsigned long shrink_zones(int priority, struct zone **zones,
|
1169 |
|
|
struct scan_control *sc)
|
1170 |
|
|
{
|
1171 |
|
|
unsigned long nr_reclaimed = 0;
|
1172 |
|
|
int i;
|
1173 |
|
|
|
1174 |
|
|
sc->all_unreclaimable = 1;
|
1175 |
|
|
for (i = 0; zones[i] != NULL; i++) {
|
1176 |
|
|
struct zone *zone = zones[i];
|
1177 |
|
|
|
1178 |
|
|
if (!populated_zone(zone))
|
1179 |
|
|
continue;
|
1180 |
|
|
|
1181 |
|
|
if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
|
1182 |
|
|
continue;
|
1183 |
|
|
|
1184 |
|
|
note_zone_scanning_priority(zone, priority);
|
1185 |
|
|
|
1186 |
|
|
if (zone_is_all_unreclaimable(zone) && priority != DEF_PRIORITY)
|
1187 |
|
|
continue; /* Let kswapd poll it */
|
1188 |
|
|
|
1189 |
|
|
sc->all_unreclaimable = 0;
|
1190 |
|
|
|
1191 |
|
|
nr_reclaimed += shrink_zone(priority, zone, sc);
|
1192 |
|
|
}
|
1193 |
|
|
return nr_reclaimed;
|
1194 |
|
|
}
|
1195 |
|
|
|
1196 |
|
|
/*
|
1197 |
|
|
* This is the main entry point to direct page reclaim.
|
1198 |
|
|
*
|
1199 |
|
|
* If a full scan of the inactive list fails to free enough memory then we
|
1200 |
|
|
* are "out of memory" and something needs to be killed.
|
1201 |
|
|
*
|
1202 |
|
|
* If the caller is !__GFP_FS then the probability of a failure is reasonably
|
1203 |
|
|
* high - the zone may be full of dirty or under-writeback pages, which this
|
1204 |
|
|
* caller can't do much about. We kick pdflush and take explicit naps in the
|
1205 |
|
|
* hope that some of these pages can be written. But if the allocating task
|
1206 |
|
|
* holds filesystem locks which prevent writeout this might not work, and the
|
1207 |
|
|
* allocation attempt will fail.
|
1208 |
|
|
*/
|
1209 |
|
|
unsigned long try_to_free_pages(struct zone **zones, int order, gfp_t gfp_mask)
|
1210 |
|
|
{
|
1211 |
|
|
int priority;
|
1212 |
|
|
int ret = 0;
|
1213 |
|
|
unsigned long total_scanned = 0;
|
1214 |
|
|
unsigned long nr_reclaimed = 0;
|
1215 |
|
|
struct reclaim_state *reclaim_state = current->reclaim_state;
|
1216 |
|
|
unsigned long lru_pages = 0;
|
1217 |
|
|
int i;
|
1218 |
|
|
struct scan_control sc = {
|
1219 |
|
|
.gfp_mask = gfp_mask,
|
1220 |
|
|
.may_writepage = !laptop_mode,
|
1221 |
|
|
.swap_cluster_max = SWAP_CLUSTER_MAX,
|
1222 |
|
|
.may_swap = 1,
|
1223 |
|
|
.swappiness = vm_swappiness,
|
1224 |
|
|
.order = order,
|
1225 |
|
|
};
|
1226 |
|
|
|
1227 |
|
|
count_vm_event(ALLOCSTALL);
|
1228 |
|
|
|
1229 |
|
|
for (i = 0; zones[i] != NULL; i++) {
|
1230 |
|
|
struct zone *zone = zones[i];
|
1231 |
|
|
|
1232 |
|
|
if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
|
1233 |
|
|
continue;
|
1234 |
|
|
|
1235 |
|
|
lru_pages += zone_page_state(zone, NR_ACTIVE)
|
1236 |
|
|
+ zone_page_state(zone, NR_INACTIVE);
|
1237 |
|
|
}
|
1238 |
|
|
|
1239 |
|
|
for (priority = DEF_PRIORITY; priority >= 0; priority--) {
|
1240 |
|
|
sc.nr_scanned = 0;
|
1241 |
|
|
if (!priority)
|
1242 |
|
|
disable_swap_token();
|
1243 |
|
|
nr_reclaimed += shrink_zones(priority, zones, &sc);
|
1244 |
|
|
shrink_slab(sc.nr_scanned, gfp_mask, lru_pages);
|
1245 |
|
|
if (reclaim_state) {
|
1246 |
|
|
nr_reclaimed += reclaim_state->reclaimed_slab;
|
1247 |
|
|
reclaim_state->reclaimed_slab = 0;
|
1248 |
|
|
}
|
1249 |
|
|
total_scanned += sc.nr_scanned;
|
1250 |
|
|
if (nr_reclaimed >= sc.swap_cluster_max) {
|
1251 |
|
|
ret = 1;
|
1252 |
|
|
goto out;
|
1253 |
|
|
}
|
1254 |
|
|
|
1255 |
|
|
/*
|
1256 |
|
|
* Try to write back as many pages as we just scanned. This
|
1257 |
|
|
* tends to cause slow streaming writers to write data to the
|
1258 |
|
|
* disk smoothly, at the dirtying rate, which is nice. But
|
1259 |
|
|
* that's undesirable in laptop mode, where we *want* lumpy
|
1260 |
|
|
* writeout. So in laptop mode, write out the whole world.
|
1261 |
|
|
*/
|
1262 |
|
|
if (total_scanned > sc.swap_cluster_max +
|
1263 |
|
|
sc.swap_cluster_max / 2) {
|
1264 |
|
|
wakeup_pdflush(laptop_mode ? 0 : total_scanned);
|
1265 |
|
|
sc.may_writepage = 1;
|
1266 |
|
|
}
|
1267 |
|
|
|
1268 |
|
|
/* Take a nap, wait for some writeback to complete */
|
1269 |
|
|
if (sc.nr_scanned && priority < DEF_PRIORITY - 2)
|
1270 |
|
|
congestion_wait(WRITE, HZ/10);
|
1271 |
|
|
}
|
1272 |
|
|
/* top priority shrink_caches still had more to do? don't OOM, then */
|
1273 |
|
|
if (!sc.all_unreclaimable)
|
1274 |
|
|
ret = 1;
|
1275 |
|
|
out:
|
1276 |
|
|
/*
|
1277 |
|
|
* Now that we've scanned all the zones at this priority level, note
|
1278 |
|
|
* that level within the zone so that the next thread which performs
|
1279 |
|
|
* scanning of this zone will immediately start out at this priority
|
1280 |
|
|
* level. This affects only the decision whether or not to bring
|
1281 |
|
|
* mapped pages onto the inactive list.
|
1282 |
|
|
*/
|
1283 |
|
|
if (priority < 0)
|
1284 |
|
|
priority = 0;
|
1285 |
|
|
for (i = 0; zones[i] != NULL; i++) {
|
1286 |
|
|
struct zone *zone = zones[i];
|
1287 |
|
|
|
1288 |
|
|
if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
|
1289 |
|
|
continue;
|
1290 |
|
|
|
1291 |
|
|
zone->prev_priority = priority;
|
1292 |
|
|
}
|
1293 |
|
|
return ret;
|
1294 |
|
|
}
|
1295 |
|
|
|
1296 |
|
|
/*
|
1297 |
|
|
* For kswapd, balance_pgdat() will work across all this node's zones until
|
1298 |
|
|
* they are all at pages_high.
|
1299 |
|
|
*
|
1300 |
|
|
* Returns the number of pages which were actually freed.
|
1301 |
|
|
*
|
1302 |
|
|
* There is special handling here for zones which are full of pinned pages.
|
1303 |
|
|
* This can happen if the pages are all mlocked, or if they are all used by
|
1304 |
|
|
* device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb.
|
1305 |
|
|
* What we do is to detect the case where all pages in the zone have been
|
1306 |
|
|
* scanned twice and there has been zero successful reclaim. Mark the zone as
|
1307 |
|
|
* dead and from now on, only perform a short scan. Basically we're polling
|
1308 |
|
|
* the zone for when the problem goes away.
|
1309 |
|
|
*
|
1310 |
|
|
* kswapd scans the zones in the highmem->normal->dma direction. It skips
|
1311 |
|
|
* zones which have free_pages > pages_high, but once a zone is found to have
|
1312 |
|
|
* free_pages <= pages_high, we scan that zone and the lower zones regardless
|
1313 |
|
|
* of the number of free pages in the lower zones. This interoperates with
|
1314 |
|
|
* the page allocator fallback scheme to ensure that aging of pages is balanced
|
1315 |
|
|
* across the zones.
|
1316 |
|
|
*/
|
1317 |
|
|
static unsigned long balance_pgdat(pg_data_t *pgdat, int order)
|
1318 |
|
|
{
|
1319 |
|
|
int all_zones_ok;
|
1320 |
|
|
int priority;
|
1321 |
|
|
int i;
|
1322 |
|
|
unsigned long total_scanned;
|
1323 |
|
|
unsigned long nr_reclaimed;
|
1324 |
|
|
struct reclaim_state *reclaim_state = current->reclaim_state;
|
1325 |
|
|
struct scan_control sc = {
|
1326 |
|
|
.gfp_mask = GFP_KERNEL,
|
1327 |
|
|
.may_swap = 1,
|
1328 |
|
|
.swap_cluster_max = SWAP_CLUSTER_MAX,
|
1329 |
|
|
.swappiness = vm_swappiness,
|
1330 |
|
|
.order = order,
|
1331 |
|
|
};
|
1332 |
|
|
/*
|
1333 |
|
|
* temp_priority is used to remember the scanning priority at which
|
1334 |
|
|
* this zone was successfully refilled to free_pages == pages_high.
|
1335 |
|
|
*/
|
1336 |
|
|
int temp_priority[MAX_NR_ZONES];
|
1337 |
|
|
|
1338 |
|
|
loop_again:
|
1339 |
|
|
total_scanned = 0;
|
1340 |
|
|
nr_reclaimed = 0;
|
1341 |
|
|
sc.may_writepage = !laptop_mode;
|
1342 |
|
|
count_vm_event(PAGEOUTRUN);
|
1343 |
|
|
|
1344 |
|
|
for (i = 0; i < pgdat->nr_zones; i++)
|
1345 |
|
|
temp_priority[i] = DEF_PRIORITY;
|
1346 |
|
|
|
1347 |
|
|
for (priority = DEF_PRIORITY; priority >= 0; priority--) {
|
1348 |
|
|
int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
|
1349 |
|
|
unsigned long lru_pages = 0;
|
1350 |
|
|
|
1351 |
|
|
/* The swap token gets in the way of swapout... */
|
1352 |
|
|
if (!priority)
|
1353 |
|
|
disable_swap_token();
|
1354 |
|
|
|
1355 |
|
|
all_zones_ok = 1;
|
1356 |
|
|
|
1357 |
|
|
/*
|
1358 |
|
|
* Scan in the highmem->dma direction for the highest
|
1359 |
|
|
* zone which needs scanning
|
1360 |
|
|
*/
|
1361 |
|
|
for (i = pgdat->nr_zones - 1; i >= 0; i--) {
|
1362 |
|
|
struct zone *zone = pgdat->node_zones + i;
|
1363 |
|
|
|
1364 |
|
|
if (!populated_zone(zone))
|
1365 |
|
|
continue;
|
1366 |
|
|
|
1367 |
|
|
if (zone_is_all_unreclaimable(zone) &&
|
1368 |
|
|
priority != DEF_PRIORITY)
|
1369 |
|
|
continue;
|
1370 |
|
|
|
1371 |
|
|
if (!zone_watermark_ok(zone, order, zone->pages_high,
|
1372 |
|
|
0, 0)) {
|
1373 |
|
|
end_zone = i;
|
1374 |
|
|
break;
|
1375 |
|
|
}
|
1376 |
|
|
}
|
1377 |
|
|
if (i < 0)
|
1378 |
|
|
goto out;
|
1379 |
|
|
|
1380 |
|
|
for (i = 0; i <= end_zone; i++) {
|
1381 |
|
|
struct zone *zone = pgdat->node_zones + i;
|
1382 |
|
|
|
1383 |
|
|
lru_pages += zone_page_state(zone, NR_ACTIVE)
|
1384 |
|
|
+ zone_page_state(zone, NR_INACTIVE);
|
1385 |
|
|
}
|
1386 |
|
|
|
1387 |
|
|
/*
|
1388 |
|
|
* Now scan the zone in the dma->highmem direction, stopping
|
1389 |
|
|
* at the last zone which needs scanning.
|
1390 |
|
|
*
|
1391 |
|
|
* We do this because the page allocator works in the opposite
|
1392 |
|
|
* direction. This prevents the page allocator from allocating
|
1393 |
|
|
* pages behind kswapd's direction of progress, which would
|
1394 |
|
|
* cause too much scanning of the lower zones.
|
1395 |
|
|
*/
|
1396 |
|
|
for (i = 0; i <= end_zone; i++) {
|
1397 |
|
|
struct zone *zone = pgdat->node_zones + i;
|
1398 |
|
|
int nr_slab;
|
1399 |
|
|
|
1400 |
|
|
if (!populated_zone(zone))
|
1401 |
|
|
continue;
|
1402 |
|
|
|
1403 |
|
|
if (zone_is_all_unreclaimable(zone) &&
|
1404 |
|
|
priority != DEF_PRIORITY)
|
1405 |
|
|
continue;
|
1406 |
|
|
|
1407 |
|
|
if (!zone_watermark_ok(zone, order, zone->pages_high,
|
1408 |
|
|
end_zone, 0))
|
1409 |
|
|
all_zones_ok = 0;
|
1410 |
|
|
temp_priority[i] = priority;
|
1411 |
|
|
sc.nr_scanned = 0;
|
1412 |
|
|
note_zone_scanning_priority(zone, priority);
|
1413 |
|
|
/*
|
1414 |
|
|
* We put equal pressure on every zone, unless one
|
1415 |
|
|
* zone has way too many pages free already.
|
1416 |
|
|
*/
|
1417 |
|
|
if (!zone_watermark_ok(zone, order, 8*zone->pages_high,
|
1418 |
|
|
end_zone, 0))
|
1419 |
|
|
nr_reclaimed += shrink_zone(priority, zone, &sc);
|
1420 |
|
|
reclaim_state->reclaimed_slab = 0;
|
1421 |
|
|
nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,
|
1422 |
|
|
lru_pages);
|
1423 |
|
|
nr_reclaimed += reclaim_state->reclaimed_slab;
|
1424 |
|
|
total_scanned += sc.nr_scanned;
|
1425 |
|
|
if (zone_is_all_unreclaimable(zone))
|
1426 |
|
|
continue;
|
1427 |
|
|
if (nr_slab == 0 && zone->pages_scanned >=
|
1428 |
|
|
(zone_page_state(zone, NR_ACTIVE)
|
1429 |
|
|
+ zone_page_state(zone, NR_INACTIVE)) * 6)
|
1430 |
|
|
zone_set_flag(zone,
|
1431 |
|
|
ZONE_ALL_UNRECLAIMABLE);
|
1432 |
|
|
/*
|
1433 |
|
|
* If we've done a decent amount of scanning and
|
1434 |
|
|
* the reclaim ratio is low, start doing writepage
|
1435 |
|
|
* even in laptop mode
|
1436 |
|
|
*/
|
1437 |
|
|
if (total_scanned > SWAP_CLUSTER_MAX * 2 &&
|
1438 |
|
|
total_scanned > nr_reclaimed + nr_reclaimed / 2)
|
1439 |
|
|
sc.may_writepage = 1;
|
1440 |
|
|
}
|
1441 |
|
|
if (all_zones_ok)
|
1442 |
|
|
break; /* kswapd: all done */
|
1443 |
|
|
/*
|
1444 |
|
|
* OK, kswapd is getting into trouble. Take a nap, then take
|
1445 |
|
|
* another pass across the zones.
|
1446 |
|
|
*/
|
1447 |
|
|
if (total_scanned && priority < DEF_PRIORITY - 2)
|
1448 |
|
|
congestion_wait(WRITE, HZ/10);
|
1449 |
|
|
|
1450 |
|
|
/*
|
1451 |
|
|
* We do this so kswapd doesn't build up large priorities for
|
1452 |
|
|
* example when it is freeing in parallel with allocators. It
|
1453 |
|
|
* matches the direct reclaim path behaviour in terms of impact
|
1454 |
|
|
* on zone->*_priority.
|
1455 |
|
|
*/
|
1456 |
|
|
if (nr_reclaimed >= SWAP_CLUSTER_MAX)
|
1457 |
|
|
break;
|
1458 |
|
|
}
|
1459 |
|
|
out:
|
1460 |
|
|
/*
|
1461 |
|
|
* Note within each zone the priority level at which this zone was
|
1462 |
|
|
* brought into a happy state. So that the next thread which scans this
|
1463 |
|
|
* zone will start out at that priority level.
|
1464 |
|
|
*/
|
1465 |
|
|
for (i = 0; i < pgdat->nr_zones; i++) {
|
1466 |
|
|
struct zone *zone = pgdat->node_zones + i;
|
1467 |
|
|
|
1468 |
|
|
zone->prev_priority = temp_priority[i];
|
1469 |
|
|
}
|
1470 |
|
|
if (!all_zones_ok) {
|
1471 |
|
|
cond_resched();
|
1472 |
|
|
|
1473 |
|
|
try_to_freeze();
|
1474 |
|
|
|
1475 |
|
|
goto loop_again;
|
1476 |
|
|
}
|
1477 |
|
|
|
1478 |
|
|
return nr_reclaimed;
|
1479 |
|
|
}
|
1480 |
|
|
|
1481 |
|
|
/*
|
1482 |
|
|
* The background pageout daemon, started as a kernel thread
|
1483 |
|
|
* from the init process.
|
1484 |
|
|
*
|
1485 |
|
|
* This basically trickles out pages so that we have _some_
|
1486 |
|
|
* free memory available even if there is no other activity
|
1487 |
|
|
* that frees anything up. This is needed for things like routing
|
1488 |
|
|
* etc, where we otherwise might have all activity going on in
|
1489 |
|
|
* asynchronous contexts that cannot page things out.
|
1490 |
|
|
*
|
1491 |
|
|
* If there are applications that are active memory-allocators
|
1492 |
|
|
* (most normal use), this basically shouldn't matter.
|
1493 |
|
|
*/
|
1494 |
|
|
static int kswapd(void *p)
|
1495 |
|
|
{
|
1496 |
|
|
unsigned long order;
|
1497 |
|
|
pg_data_t *pgdat = (pg_data_t*)p;
|
1498 |
|
|
struct task_struct *tsk = current;
|
1499 |
|
|
DEFINE_WAIT(wait);
|
1500 |
|
|
struct reclaim_state reclaim_state = {
|
1501 |
|
|
.reclaimed_slab = 0,
|
1502 |
|
|
};
|
1503 |
|
|
cpumask_t cpumask;
|
1504 |
|
|
|
1505 |
|
|
cpumask = node_to_cpumask(pgdat->node_id);
|
1506 |
|
|
if (!cpus_empty(cpumask))
|
1507 |
|
|
set_cpus_allowed(tsk, cpumask);
|
1508 |
|
|
current->reclaim_state = &reclaim_state;
|
1509 |
|
|
|
1510 |
|
|
/*
|
1511 |
|
|
* Tell the memory management that we're a "memory allocator",
|
1512 |
|
|
* and that if we need more memory we should get access to it
|
1513 |
|
|
* regardless (see "__alloc_pages()"). "kswapd" should
|
1514 |
|
|
* never get caught in the normal page freeing logic.
|
1515 |
|
|
*
|
1516 |
|
|
* (Kswapd normally doesn't need memory anyway, but sometimes
|
1517 |
|
|
* you need a small amount of memory in order to be able to
|
1518 |
|
|
* page out something else, and this flag essentially protects
|
1519 |
|
|
* us from recursively trying to free more memory as we're
|
1520 |
|
|
* trying to free the first piece of memory in the first place).
|
1521 |
|
|
*/
|
1522 |
|
|
tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
|
1523 |
|
|
set_freezable();
|
1524 |
|
|
|
1525 |
|
|
order = 0;
|
1526 |
|
|
for ( ; ; ) {
|
1527 |
|
|
unsigned long new_order;
|
1528 |
|
|
|
1529 |
|
|
prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
|
1530 |
|
|
new_order = pgdat->kswapd_max_order;
|
1531 |
|
|
pgdat->kswapd_max_order = 0;
|
1532 |
|
|
if (order < new_order) {
|
1533 |
|
|
/*
|
1534 |
|
|
* Don't sleep if someone wants a larger 'order'
|
1535 |
|
|
* allocation
|
1536 |
|
|
*/
|
1537 |
|
|
order = new_order;
|
1538 |
|
|
} else {
|
1539 |
|
|
if (!freezing(current))
|
1540 |
|
|
schedule();
|
1541 |
|
|
|
1542 |
|
|
order = pgdat->kswapd_max_order;
|
1543 |
|
|
}
|
1544 |
|
|
finish_wait(&pgdat->kswapd_wait, &wait);
|
1545 |
|
|
|
1546 |
|
|
if (!try_to_freeze()) {
|
1547 |
|
|
/* We can speed up thawing tasks if we don't call
|
1548 |
|
|
* balance_pgdat after returning from the refrigerator
|
1549 |
|
|
*/
|
1550 |
|
|
balance_pgdat(pgdat, order);
|
1551 |
|
|
}
|
1552 |
|
|
}
|
1553 |
|
|
return 0;
|
1554 |
|
|
}
|
1555 |
|
|
|
1556 |
|
|
/*
|
1557 |
|
|
* A zone is low on free memory, so wake its kswapd task to service it.
|
1558 |
|
|
*/
|
1559 |
|
|
void wakeup_kswapd(struct zone *zone, int order)
|
1560 |
|
|
{
|
1561 |
|
|
pg_data_t *pgdat;
|
1562 |
|
|
|
1563 |
|
|
if (!populated_zone(zone))
|
1564 |
|
|
return;
|
1565 |
|
|
|
1566 |
|
|
pgdat = zone->zone_pgdat;
|
1567 |
|
|
if (zone_watermark_ok(zone, order, zone->pages_low, 0, 0))
|
1568 |
|
|
return;
|
1569 |
|
|
if (pgdat->kswapd_max_order < order)
|
1570 |
|
|
pgdat->kswapd_max_order = order;
|
1571 |
|
|
if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
|
1572 |
|
|
return;
|
1573 |
|
|
if (!waitqueue_active(&pgdat->kswapd_wait))
|
1574 |
|
|
return;
|
1575 |
|
|
wake_up_interruptible(&pgdat->kswapd_wait);
|
1576 |
|
|
}
|
1577 |
|
|
|
1578 |
|
|
#ifdef CONFIG_PM
|
1579 |
|
|
/*
|
1580 |
|
|
* Helper function for shrink_all_memory(). Tries to reclaim 'nr_pages' pages
|
1581 |
|
|
* from LRU lists system-wide, for given pass and priority, and returns the
|
1582 |
|
|
* number of reclaimed pages
|
1583 |
|
|
*
|
1584 |
|
|
* For pass > 3 we also try to shrink the LRU lists that contain a few pages
|
1585 |
|
|
*/
|
1586 |
|
|
static unsigned long shrink_all_zones(unsigned long nr_pages, int prio,
|
1587 |
|
|
int pass, struct scan_control *sc)
|
1588 |
|
|
{
|
1589 |
|
|
struct zone *zone;
|
1590 |
|
|
unsigned long nr_to_scan, ret = 0;
|
1591 |
|
|
|
1592 |
|
|
for_each_zone(zone) {
|
1593 |
|
|
|
1594 |
|
|
if (!populated_zone(zone))
|
1595 |
|
|
continue;
|
1596 |
|
|
|
1597 |
|
|
if (zone_is_all_unreclaimable(zone) && prio != DEF_PRIORITY)
|
1598 |
|
|
continue;
|
1599 |
|
|
|
1600 |
|
|
/* For pass = 0 we don't shrink the active list */
|
1601 |
|
|
if (pass > 0) {
|
1602 |
|
|
zone->nr_scan_active +=
|
1603 |
|
|
(zone_page_state(zone, NR_ACTIVE) >> prio) + 1;
|
1604 |
|
|
if (zone->nr_scan_active >= nr_pages || pass > 3) {
|
1605 |
|
|
zone->nr_scan_active = 0;
|
1606 |
|
|
nr_to_scan = min(nr_pages,
|
1607 |
|
|
zone_page_state(zone, NR_ACTIVE));
|
1608 |
|
|
shrink_active_list(nr_to_scan, zone, sc, prio);
|
1609 |
|
|
}
|
1610 |
|
|
}
|
1611 |
|
|
|
1612 |
|
|
zone->nr_scan_inactive +=
|
1613 |
|
|
(zone_page_state(zone, NR_INACTIVE) >> prio) + 1;
|
1614 |
|
|
if (zone->nr_scan_inactive >= nr_pages || pass > 3) {
|
1615 |
|
|
zone->nr_scan_inactive = 0;
|
1616 |
|
|
nr_to_scan = min(nr_pages,
|
1617 |
|
|
zone_page_state(zone, NR_INACTIVE));
|
1618 |
|
|
ret += shrink_inactive_list(nr_to_scan, zone, sc);
|
1619 |
|
|
if (ret >= nr_pages)
|
1620 |
|
|
return ret;
|
1621 |
|
|
}
|
1622 |
|
|
}
|
1623 |
|
|
|
1624 |
|
|
return ret;
|
1625 |
|
|
}
|
1626 |
|
|
|
1627 |
|
|
static unsigned long count_lru_pages(void)
|
1628 |
|
|
{
|
1629 |
|
|
return global_page_state(NR_ACTIVE) + global_page_state(NR_INACTIVE);
|
1630 |
|
|
}
|
1631 |
|
|
|
1632 |
|
|
/*
|
1633 |
|
|
* Try to free `nr_pages' of memory, system-wide, and return the number of
|
1634 |
|
|
* freed pages.
|
1635 |
|
|
*
|
1636 |
|
|
* Rather than trying to age LRUs the aim is to preserve the overall
|
1637 |
|
|
* LRU order by reclaiming preferentially
|
1638 |
|
|
* inactive > active > active referenced > active mapped
|
1639 |
|
|
*/
|
1640 |
|
|
unsigned long shrink_all_memory(unsigned long nr_pages)
|
1641 |
|
|
{
|
1642 |
|
|
unsigned long lru_pages, nr_slab;
|
1643 |
|
|
unsigned long ret = 0;
|
1644 |
|
|
int pass;
|
1645 |
|
|
struct reclaim_state reclaim_state;
|
1646 |
|
|
struct scan_control sc = {
|
1647 |
|
|
.gfp_mask = GFP_KERNEL,
|
1648 |
|
|
.may_swap = 0,
|
1649 |
|
|
.swap_cluster_max = nr_pages,
|
1650 |
|
|
.may_writepage = 1,
|
1651 |
|
|
.swappiness = vm_swappiness,
|
1652 |
|
|
};
|
1653 |
|
|
|
1654 |
|
|
current->reclaim_state = &reclaim_state;
|
1655 |
|
|
|
1656 |
|
|
lru_pages = count_lru_pages();
|
1657 |
|
|
nr_slab = global_page_state(NR_SLAB_RECLAIMABLE);
|
1658 |
|
|
/* If slab caches are huge, it's better to hit them first */
|
1659 |
|
|
while (nr_slab >= lru_pages) {
|
1660 |
|
|
reclaim_state.reclaimed_slab = 0;
|
1661 |
|
|
shrink_slab(nr_pages, sc.gfp_mask, lru_pages);
|
1662 |
|
|
if (!reclaim_state.reclaimed_slab)
|
1663 |
|
|
break;
|
1664 |
|
|
|
1665 |
|
|
ret += reclaim_state.reclaimed_slab;
|
1666 |
|
|
if (ret >= nr_pages)
|
1667 |
|
|
goto out;
|
1668 |
|
|
|
1669 |
|
|
nr_slab -= reclaim_state.reclaimed_slab;
|
1670 |
|
|
}
|
1671 |
|
|
|
1672 |
|
|
/*
|
1673 |
|
|
* We try to shrink LRUs in 5 passes:
|
1674 |
|
|
* 0 = Reclaim from inactive_list only
|
1675 |
|
|
* 1 = Reclaim from active list but don't reclaim mapped
|
1676 |
|
|
* 2 = 2nd pass of type 1
|
1677 |
|
|
* 3 = Reclaim mapped (normal reclaim)
|
1678 |
|
|
* 4 = 2nd pass of type 3
|
1679 |
|
|
*/
|
1680 |
|
|
for (pass = 0; pass < 5; pass++) {
|
1681 |
|
|
int prio;
|
1682 |
|
|
|
1683 |
|
|
/* Force reclaiming mapped pages in the passes #3 and #4 */
|
1684 |
|
|
if (pass > 2) {
|
1685 |
|
|
sc.may_swap = 1;
|
1686 |
|
|
sc.swappiness = 100;
|
1687 |
|
|
}
|
1688 |
|
|
|
1689 |
|
|
for (prio = DEF_PRIORITY; prio >= 0; prio--) {
|
1690 |
|
|
unsigned long nr_to_scan = nr_pages - ret;
|
1691 |
|
|
|
1692 |
|
|
sc.nr_scanned = 0;
|
1693 |
|
|
ret += shrink_all_zones(nr_to_scan, prio, pass, &sc);
|
1694 |
|
|
if (ret >= nr_pages)
|
1695 |
|
|
goto out;
|
1696 |
|
|
|
1697 |
|
|
reclaim_state.reclaimed_slab = 0;
|
1698 |
|
|
shrink_slab(sc.nr_scanned, sc.gfp_mask,
|
1699 |
|
|
count_lru_pages());
|
1700 |
|
|
ret += reclaim_state.reclaimed_slab;
|
1701 |
|
|
if (ret >= nr_pages)
|
1702 |
|
|
goto out;
|
1703 |
|
|
|
1704 |
|
|
if (sc.nr_scanned && prio < DEF_PRIORITY - 2)
|
1705 |
|
|
congestion_wait(WRITE, HZ / 10);
|
1706 |
|
|
}
|
1707 |
|
|
}
|
1708 |
|
|
|
1709 |
|
|
/*
|
1710 |
|
|
* If ret = 0, we could not shrink LRUs, but there may be something
|
1711 |
|
|
* in slab caches
|
1712 |
|
|
*/
|
1713 |
|
|
if (!ret) {
|
1714 |
|
|
do {
|
1715 |
|
|
reclaim_state.reclaimed_slab = 0;
|
1716 |
|
|
shrink_slab(nr_pages, sc.gfp_mask, count_lru_pages());
|
1717 |
|
|
ret += reclaim_state.reclaimed_slab;
|
1718 |
|
|
} while (ret < nr_pages && reclaim_state.reclaimed_slab > 0);
|
1719 |
|
|
}
|
1720 |
|
|
|
1721 |
|
|
out:
|
1722 |
|
|
current->reclaim_state = NULL;
|
1723 |
|
|
|
1724 |
|
|
return ret;
|
1725 |
|
|
}
|
1726 |
|
|
#endif
|
1727 |
|
|
|
1728 |
|
|
/* It's optimal to keep kswapds on the same CPUs as their memory, but
|
1729 |
|
|
not required for correctness. So if the last cpu in a node goes
|
1730 |
|
|
away, we get changed to run anywhere: as the first one comes back,
|
1731 |
|
|
restore their cpu bindings. */
|
1732 |
|
|
static int __devinit cpu_callback(struct notifier_block *nfb,
|
1733 |
|
|
unsigned long action, void *hcpu)
|
1734 |
|
|
{
|
1735 |
|
|
pg_data_t *pgdat;
|
1736 |
|
|
cpumask_t mask;
|
1737 |
|
|
int nid;
|
1738 |
|
|
|
1739 |
|
|
if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) {
|
1740 |
|
|
for_each_node_state(nid, N_HIGH_MEMORY) {
|
1741 |
|
|
pgdat = NODE_DATA(nid);
|
1742 |
|
|
mask = node_to_cpumask(pgdat->node_id);
|
1743 |
|
|
if (any_online_cpu(mask) != NR_CPUS)
|
1744 |
|
|
/* One of our CPUs online: restore mask */
|
1745 |
|
|
set_cpus_allowed(pgdat->kswapd, mask);
|
1746 |
|
|
}
|
1747 |
|
|
}
|
1748 |
|
|
return NOTIFY_OK;
|
1749 |
|
|
}
|
1750 |
|
|
|
1751 |
|
|
/*
|
1752 |
|
|
* This kswapd start function will be called by init and node-hot-add.
|
1753 |
|
|
* On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added.
|
1754 |
|
|
*/
|
1755 |
|
|
int kswapd_run(int nid)
|
1756 |
|
|
{
|
1757 |
|
|
pg_data_t *pgdat = NODE_DATA(nid);
|
1758 |
|
|
int ret = 0;
|
1759 |
|
|
|
1760 |
|
|
if (pgdat->kswapd)
|
1761 |
|
|
return 0;
|
1762 |
|
|
|
1763 |
|
|
pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid);
|
1764 |
|
|
if (IS_ERR(pgdat->kswapd)) {
|
1765 |
|
|
/* failure at boot is fatal */
|
1766 |
|
|
BUG_ON(system_state == SYSTEM_BOOTING);
|
1767 |
|
|
printk("Failed to start kswapd on node %d\n",nid);
|
1768 |
|
|
ret = -1;
|
1769 |
|
|
}
|
1770 |
|
|
return ret;
|
1771 |
|
|
}
|
1772 |
|
|
|
1773 |
|
|
static int __init kswapd_init(void)
|
1774 |
|
|
{
|
1775 |
|
|
int nid;
|
1776 |
|
|
|
1777 |
|
|
swap_setup();
|
1778 |
|
|
for_each_node_state(nid, N_HIGH_MEMORY)
|
1779 |
|
|
kswapd_run(nid);
|
1780 |
|
|
hotcpu_notifier(cpu_callback, 0);
|
1781 |
|
|
return 0;
|
1782 |
|
|
}
|
1783 |
|
|
|
1784 |
|
|
module_init(kswapd_init)
|
1785 |
|
|
|
1786 |
|
|
#ifdef CONFIG_NUMA
|
1787 |
|
|
/*
|
1788 |
|
|
* Zone reclaim mode
|
1789 |
|
|
*
|
1790 |
|
|
* If non-zero call zone_reclaim when the number of free pages falls below
|
1791 |
|
|
* the watermarks.
|
1792 |
|
|
*/
|
1793 |
|
|
int zone_reclaim_mode __read_mostly;
|
1794 |
|
|
|
1795 |
|
|
#define RECLAIM_OFF 0
|
1796 |
|
|
#define RECLAIM_ZONE (1<<0) /* Run shrink_cache on the zone */
|
1797 |
|
|
#define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */
|
1798 |
|
|
#define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */
|
1799 |
|
|
|
1800 |
|
|
/*
|
1801 |
|
|
* Priority for ZONE_RECLAIM. This determines the fraction of pages
|
1802 |
|
|
* of a node considered for each zone_reclaim. 4 scans 1/16th of
|
1803 |
|
|
* a zone.
|
1804 |
|
|
*/
|
1805 |
|
|
#define ZONE_RECLAIM_PRIORITY 4
|
1806 |
|
|
|
1807 |
|
|
/*
|
1808 |
|
|
* Percentage of pages in a zone that must be unmapped for zone_reclaim to
|
1809 |
|
|
* occur.
|
1810 |
|
|
*/
|
1811 |
|
|
int sysctl_min_unmapped_ratio = 1;
|
1812 |
|
|
|
1813 |
|
|
/*
|
1814 |
|
|
* If the number of slab pages in a zone grows beyond this percentage then
|
1815 |
|
|
* slab reclaim needs to occur.
|
1816 |
|
|
*/
|
1817 |
|
|
int sysctl_min_slab_ratio = 5;
|
1818 |
|
|
|
1819 |
|
|
/*
|
1820 |
|
|
* Try to free up some pages from this zone through reclaim.
|
1821 |
|
|
*/
|
1822 |
|
|
static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
|
1823 |
|
|
{
|
1824 |
|
|
/* Minimum pages needed in order to stay on node */
|
1825 |
|
|
const unsigned long nr_pages = 1 << order;
|
1826 |
|
|
struct task_struct *p = current;
|
1827 |
|
|
struct reclaim_state reclaim_state;
|
1828 |
|
|
int priority;
|
1829 |
|
|
unsigned long nr_reclaimed = 0;
|
1830 |
|
|
struct scan_control sc = {
|
1831 |
|
|
.may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
|
1832 |
|
|
.may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP),
|
1833 |
|
|
.swap_cluster_max = max_t(unsigned long, nr_pages,
|
1834 |
|
|
SWAP_CLUSTER_MAX),
|
1835 |
|
|
.gfp_mask = gfp_mask,
|
1836 |
|
|
.swappiness = vm_swappiness,
|
1837 |
|
|
};
|
1838 |
|
|
unsigned long slab_reclaimable;
|
1839 |
|
|
|
1840 |
|
|
disable_swap_token();
|
1841 |
|
|
cond_resched();
|
1842 |
|
|
/*
|
1843 |
|
|
* We need to be able to allocate from the reserves for RECLAIM_SWAP
|
1844 |
|
|
* and we also need to be able to write out pages for RECLAIM_WRITE
|
1845 |
|
|
* and RECLAIM_SWAP.
|
1846 |
|
|
*/
|
1847 |
|
|
p->flags |= PF_MEMALLOC | PF_SWAPWRITE;
|
1848 |
|
|
reclaim_state.reclaimed_slab = 0;
|
1849 |
|
|
p->reclaim_state = &reclaim_state;
|
1850 |
|
|
|
1851 |
|
|
if (zone_page_state(zone, NR_FILE_PAGES) -
|
1852 |
|
|
zone_page_state(zone, NR_FILE_MAPPED) >
|
1853 |
|
|
zone->min_unmapped_pages) {
|
1854 |
|
|
/*
|
1855 |
|
|
* Free memory by calling shrink zone with increasing
|
1856 |
|
|
* priorities until we have enough memory freed.
|
1857 |
|
|
*/
|
1858 |
|
|
priority = ZONE_RECLAIM_PRIORITY;
|
1859 |
|
|
do {
|
1860 |
|
|
note_zone_scanning_priority(zone, priority);
|
1861 |
|
|
nr_reclaimed += shrink_zone(priority, zone, &sc);
|
1862 |
|
|
priority--;
|
1863 |
|
|
} while (priority >= 0 && nr_reclaimed < nr_pages);
|
1864 |
|
|
}
|
1865 |
|
|
|
1866 |
|
|
slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
|
1867 |
|
|
if (slab_reclaimable > zone->min_slab_pages) {
|
1868 |
|
|
/*
|
1869 |
|
|
* shrink_slab() does not currently allow us to determine how
|
1870 |
|
|
* many pages were freed in this zone. So we take the current
|
1871 |
|
|
* number of slab pages and shake the slab until it is reduced
|
1872 |
|
|
* by the same nr_pages that we used for reclaiming unmapped
|
1873 |
|
|
* pages.
|
1874 |
|
|
*
|
1875 |
|
|
* Note that shrink_slab will free memory on all zones and may
|
1876 |
|
|
* take a long time.
|
1877 |
|
|
*/
|
1878 |
|
|
while (shrink_slab(sc.nr_scanned, gfp_mask, order) &&
|
1879 |
|
|
zone_page_state(zone, NR_SLAB_RECLAIMABLE) >
|
1880 |
|
|
slab_reclaimable - nr_pages)
|
1881 |
|
|
;
|
1882 |
|
|
|
1883 |
|
|
/*
|
1884 |
|
|
* Update nr_reclaimed by the number of slab pages we
|
1885 |
|
|
* reclaimed from this zone.
|
1886 |
|
|
*/
|
1887 |
|
|
nr_reclaimed += slab_reclaimable -
|
1888 |
|
|
zone_page_state(zone, NR_SLAB_RECLAIMABLE);
|
1889 |
|
|
}
|
1890 |
|
|
|
1891 |
|
|
p->reclaim_state = NULL;
|
1892 |
|
|
current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE);
|
1893 |
|
|
return nr_reclaimed >= nr_pages;
|
1894 |
|
|
}
|
1895 |
|
|
|
1896 |
|
|
int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
|
1897 |
|
|
{
|
1898 |
|
|
int node_id;
|
1899 |
|
|
int ret;
|
1900 |
|
|
|
1901 |
|
|
/*
|
1902 |
|
|
* Zone reclaim reclaims unmapped file backed pages and
|
1903 |
|
|
* slab pages if we are over the defined limits.
|
1904 |
|
|
*
|
1905 |
|
|
* A small portion of unmapped file backed pages is needed for
|
1906 |
|
|
* file I/O otherwise pages read by file I/O will be immediately
|
1907 |
|
|
* thrown out if the zone is overallocated. So we do not reclaim
|
1908 |
|
|
* if less than a specified percentage of the zone is used by
|
1909 |
|
|
* unmapped file backed pages.
|
1910 |
|
|
*/
|
1911 |
|
|
if (zone_page_state(zone, NR_FILE_PAGES) -
|
1912 |
|
|
zone_page_state(zone, NR_FILE_MAPPED) <= zone->min_unmapped_pages
|
1913 |
|
|
&& zone_page_state(zone, NR_SLAB_RECLAIMABLE)
|
1914 |
|
|
<= zone->min_slab_pages)
|
1915 |
|
|
return 0;
|
1916 |
|
|
|
1917 |
|
|
if (zone_is_all_unreclaimable(zone))
|
1918 |
|
|
return 0;
|
1919 |
|
|
|
1920 |
|
|
/*
|
1921 |
|
|
* Do not scan if the allocation should not be delayed.
|
1922 |
|
|
*/
|
1923 |
|
|
if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC))
|
1924 |
|
|
return 0;
|
1925 |
|
|
|
1926 |
|
|
/*
|
1927 |
|
|
* Only run zone reclaim on the local zone or on zones that do not
|
1928 |
|
|
* have associated processors. This will favor the local processor
|
1929 |
|
|
* over remote processors and spread off node memory allocations
|
1930 |
|
|
* as wide as possible.
|
1931 |
|
|
*/
|
1932 |
|
|
node_id = zone_to_nid(zone);
|
1933 |
|
|
if (node_state(node_id, N_CPU) && node_id != numa_node_id())
|
1934 |
|
|
return 0;
|
1935 |
|
|
|
1936 |
|
|
if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED))
|
1937 |
|
|
return 0;
|
1938 |
|
|
ret = __zone_reclaim(zone, gfp_mask, order);
|
1939 |
|
|
zone_clear_flag(zone, ZONE_RECLAIM_LOCKED);
|
1940 |
|
|
|
1941 |
|
|
return ret;
|
1942 |
|
|
}
|
1943 |
|
|
#endif
|