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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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6072d13c42
NFS needs to be able to release objects that are stored in the page
cache once the page itself is no longer visible from the page cache.
This patch adds a callback to the address space operations that allows
filesystems to perform page cleanups once the page has been removed
from the page cache.
Original patch by: Linus Torvalds <torvalds@linux-foundation.org>
[trondmy: cover the cases of invalidate_inode_pages2() and
truncate_inode_pages()]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
3108 lines
84 KiB
C
3108 lines
84 KiB
C
/*
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* linux/mm/vmscan.c
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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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#include <linux/module.h>
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#include <linux/gfp.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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#include <linux/topology.h>
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#include <linux/cpu.h>
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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 <linux/memcontrol.h>
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#include <linux/delayacct.h>
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#include <linux/sysctl.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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#include "internal.h"
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#define CREATE_TRACE_POINTS
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#include <trace/events/vmscan.h>
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enum lumpy_mode {
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LUMPY_MODE_NONE,
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LUMPY_MODE_ASYNC,
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LUMPY_MODE_SYNC,
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};
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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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/* Number of pages freed so far during a call to shrink_zones() */
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unsigned long nr_reclaimed;
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/* How many pages shrink_list() should reclaim */
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unsigned long nr_to_reclaim;
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unsigned long hibernation_mode;
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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 mapped pages be reclaimed? */
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int may_unmap;
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/* Can pages be swapped as part of reclaim? */
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int may_swap;
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int swappiness;
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int order;
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/*
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* Intend to reclaim enough continuous memory rather than reclaim
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* enough amount of memory. i.e, mode for high order allocation.
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*/
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enum lumpy_mode lumpy_reclaim_mode;
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/* Which cgroup do we reclaim from */
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struct mem_cgroup *mem_cgroup;
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/*
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* Nodemask of nodes allowed by the caller. If NULL, all nodes
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* are scanned.
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*/
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nodemask_t *nodemask;
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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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static LIST_HEAD(shrinker_list);
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static DECLARE_RWSEM(shrinker_rwsem);
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#ifdef CONFIG_CGROUP_MEM_RES_CTLR
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#define scanning_global_lru(sc) (!(sc)->mem_cgroup)
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#else
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#define scanning_global_lru(sc) (1)
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#endif
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static struct zone_reclaim_stat *get_reclaim_stat(struct zone *zone,
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struct scan_control *sc)
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{
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if (!scanning_global_lru(sc))
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return mem_cgroup_get_reclaim_stat(sc->mem_cgroup, zone);
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return &zone->reclaim_stat;
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}
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static unsigned long zone_nr_lru_pages(struct zone *zone,
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struct scan_control *sc, enum lru_list lru)
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{
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if (!scanning_global_lru(sc))
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return mem_cgroup_zone_nr_pages(sc->mem_cgroup, zone, lru);
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return zone_page_state(zone, NR_LRU_BASE + lru);
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}
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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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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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*
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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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* slab reclaim versus page reclaim.
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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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unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
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unsigned long lru_pages)
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{
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struct shrinker *shrinker;
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unsigned long ret = 0;
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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;
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max_pass = (*shrinker->shrink)(shrinker, 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 "shrink_slab: %pF negative objects to "
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"delete nr=%ld\n",
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shrinker->shrink, 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)(shrinker, 0, gfp_mask);
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shrink_ret = (*shrinker->shrink)(shrinker, this_scan,
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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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static void set_lumpy_reclaim_mode(int priority, struct scan_control *sc,
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bool sync)
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{
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enum lumpy_mode mode = sync ? LUMPY_MODE_SYNC : LUMPY_MODE_ASYNC;
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/*
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* Some reclaim have alredy been failed. No worth to try synchronous
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* lumpy reclaim.
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*/
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if (sync && sc->lumpy_reclaim_mode == LUMPY_MODE_NONE)
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return;
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/*
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* If we need a large contiguous chunk of memory, or have
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* trouble getting a small set of contiguous pages, we
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* will reclaim both active and inactive pages.
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*/
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if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
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sc->lumpy_reclaim_mode = mode;
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else if (sc->order && priority < DEF_PRIORITY - 2)
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sc->lumpy_reclaim_mode = mode;
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else
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sc->lumpy_reclaim_mode = LUMPY_MODE_NONE;
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}
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static void disable_lumpy_reclaim_mode(struct scan_control *sc)
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{
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sc->lumpy_reclaim_mode = LUMPY_MODE_NONE;
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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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/*
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* A freeable page cache page is referenced only by the caller
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* that isolated the page, the page cache radix tree and
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* optional buffer heads at page->private.
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*/
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return page_count(page) - page_has_private(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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struct scan_control *sc)
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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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if (bdi == current->backing_dev_info)
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return 1;
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/* lumpy reclaim for hugepage often need a lot of write */
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if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
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return 1;
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return 0;
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}
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/*
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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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* fsync(), msync() or close().
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*
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* The tricky part is that after writepage we cannot touch the mapping: nothing
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* prevents it from being freed up. But we have a ref on the page and once
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* that page is locked, the mapping is pinned.
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*
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* We're allowed to run sleeping lock_page() here because we know the caller has
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* __GFP_FS.
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*/
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static void handle_write_error(struct address_space *mapping,
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struct page *page, int error)
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{
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lock_page_nosync(page);
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if (page_mapping(page) == mapping)
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mapping_set_error(mapping, error);
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unlock_page(page);
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}
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/* possible outcome of pageout() */
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typedef enum {
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/* failed to write page out, page is locked */
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PAGE_KEEP,
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/* move page to the active list, page is locked */
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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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PAGE_SUCCESS,
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/* page is clean and locked */
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PAGE_CLEAN,
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} pageout_t;
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/*
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* pageout is called by shrink_page_list() for each dirty page.
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* Calls ->writepage().
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*/
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static pageout_t pageout(struct page *page, struct address_space *mapping,
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struct scan_control *sc)
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{
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/*
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* If the page is dirty, only perform writeback if that write
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* will be non-blocking. To prevent this allocation from being
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* stalled by pagecache activity. But note that there may be
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* stalls if we need to run get_block(). We could test
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* PagePrivate for that.
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*
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* If this process is currently in __generic_file_aio_write() against
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* this page's queue, we can perform writeback even if that
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* will block.
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*
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* If the page is swapcache, write it back even if that would
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* block, for some throttling. This happens by accident, because
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* swap_backing_dev_info is bust: it doesn't reflect the
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* congestion state of the swapdevs. Easy to fix, if needed.
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*/
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if (!is_page_cache_freeable(page))
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return PAGE_KEEP;
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if (!mapping) {
|
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/*
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* Some data journaling orphaned pages can have
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* page->mapping == NULL while being dirty with clean buffers.
|
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*/
|
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if (page_has_private(page)) {
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if (try_to_free_buffers(page)) {
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ClearPageDirty(page);
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printk("%s: orphaned page\n", __func__);
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return PAGE_CLEAN;
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}
|
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}
|
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return PAGE_KEEP;
|
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}
|
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if (mapping->a_ops->writepage == NULL)
|
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return PAGE_ACTIVATE;
|
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if (!may_write_to_queue(mapping->backing_dev_info, sc))
|
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return PAGE_KEEP;
|
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|
|
if (clear_page_dirty_for_io(page)) {
|
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int res;
|
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struct writeback_control wbc = {
|
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.sync_mode = WB_SYNC_NONE,
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.nr_to_write = SWAP_CLUSTER_MAX,
|
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.range_start = 0,
|
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.range_end = LLONG_MAX,
|
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.for_reclaim = 1,
|
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};
|
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|
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SetPageReclaim(page);
|
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res = mapping->a_ops->writepage(page, &wbc);
|
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if (res < 0)
|
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handle_write_error(mapping, page, res);
|
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if (res == AOP_WRITEPAGE_ACTIVATE) {
|
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ClearPageReclaim(page);
|
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return PAGE_ACTIVATE;
|
|
}
|
|
|
|
/*
|
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* Wait on writeback if requested to. This happens when
|
|
* direct reclaiming a large contiguous area and the
|
|
* first attempt to free a range of pages fails.
|
|
*/
|
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if (PageWriteback(page) &&
|
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sc->lumpy_reclaim_mode == LUMPY_MODE_SYNC)
|
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wait_on_page_writeback(page);
|
|
|
|
if (!PageWriteback(page)) {
|
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/* synchronous write or broken a_ops? */
|
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ClearPageReclaim(page);
|
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}
|
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trace_mm_vmscan_writepage(page,
|
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trace_reclaim_flags(page, sc->lumpy_reclaim_mode));
|
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inc_zone_page_state(page, NR_VMSCAN_WRITE);
|
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return PAGE_SUCCESS;
|
|
}
|
|
|
|
return PAGE_CLEAN;
|
|
}
|
|
|
|
/*
|
|
* Same as remove_mapping, but if the page is removed from the mapping, it
|
|
* gets returned with a refcount of 0.
|
|
*/
|
|
static int __remove_mapping(struct address_space *mapping, struct page *page)
|
|
{
|
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BUG_ON(!PageLocked(page));
|
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BUG_ON(mapping != page_mapping(page));
|
|
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
/*
|
|
* The non racy check for a busy page.
|
|
*
|
|
* Must be careful with the order of the tests. When someone has
|
|
* a ref to the page, it may be possible that they dirty it then
|
|
* drop the reference. So if PageDirty is tested before page_count
|
|
* here, then the following race may occur:
|
|
*
|
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* get_user_pages(&page);
|
|
* [user mapping goes away]
|
|
* write_to(page);
|
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* !PageDirty(page) [good]
|
|
* SetPageDirty(page);
|
|
* put_page(page);
|
|
* !page_count(page) [good, discard it]
|
|
*
|
|
* [oops, our write_to data is lost]
|
|
*
|
|
* Reversing the order of the tests ensures such a situation cannot
|
|
* escape unnoticed. The smp_rmb is needed to ensure the page->flags
|
|
* load is not satisfied before that of page->_count.
|
|
*
|
|
* Note that if SetPageDirty is always performed via set_page_dirty,
|
|
* and thus under tree_lock, then this ordering is not required.
|
|
*/
|
|
if (!page_freeze_refs(page, 2))
|
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goto cannot_free;
|
|
/* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */
|
|
if (unlikely(PageDirty(page))) {
|
|
page_unfreeze_refs(page, 2);
|
|
goto cannot_free;
|
|
}
|
|
|
|
if (PageSwapCache(page)) {
|
|
swp_entry_t swap = { .val = page_private(page) };
|
|
__delete_from_swap_cache(page);
|
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spin_unlock_irq(&mapping->tree_lock);
|
|
swapcache_free(swap, page);
|
|
} else {
|
|
void (*freepage)(struct page *);
|
|
|
|
freepage = mapping->a_ops->freepage;
|
|
|
|
__remove_from_page_cache(page);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
mem_cgroup_uncharge_cache_page(page);
|
|
|
|
if (freepage != NULL)
|
|
freepage(page);
|
|
}
|
|
|
|
return 1;
|
|
|
|
cannot_free:
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Attempt to detach a locked page from its ->mapping. If it is dirty or if
|
|
* someone else has a ref on the page, abort and return 0. If it was
|
|
* successfully detached, return 1. Assumes the caller has a single ref on
|
|
* this page.
|
|
*/
|
|
int remove_mapping(struct address_space *mapping, struct page *page)
|
|
{
|
|
if (__remove_mapping(mapping, page)) {
|
|
/*
|
|
* Unfreezing the refcount with 1 rather than 2 effectively
|
|
* drops the pagecache ref for us without requiring another
|
|
* atomic operation.
|
|
*/
|
|
page_unfreeze_refs(page, 1);
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* putback_lru_page - put previously isolated page onto appropriate LRU list
|
|
* @page: page to be put back to appropriate lru list
|
|
*
|
|
* Add previously isolated @page to appropriate LRU list.
|
|
* Page may still be unevictable for other reasons.
|
|
*
|
|
* lru_lock must not be held, interrupts must be enabled.
|
|
*/
|
|
void putback_lru_page(struct page *page)
|
|
{
|
|
int lru;
|
|
int active = !!TestClearPageActive(page);
|
|
int was_unevictable = PageUnevictable(page);
|
|
|
|
VM_BUG_ON(PageLRU(page));
|
|
|
|
redo:
|
|
ClearPageUnevictable(page);
|
|
|
|
if (page_evictable(page, NULL)) {
|
|
/*
|
|
* For evictable pages, we can use the cache.
|
|
* In event of a race, worst case is we end up with an
|
|
* unevictable page on [in]active list.
|
|
* We know how to handle that.
|
|
*/
|
|
lru = active + page_lru_base_type(page);
|
|
lru_cache_add_lru(page, lru);
|
|
} else {
|
|
/*
|
|
* Put unevictable pages directly on zone's unevictable
|
|
* list.
|
|
*/
|
|
lru = LRU_UNEVICTABLE;
|
|
add_page_to_unevictable_list(page);
|
|
/*
|
|
* When racing with an mlock clearing (page is
|
|
* unlocked), make sure that if the other thread does
|
|
* not observe our setting of PG_lru and fails
|
|
* isolation, we see PG_mlocked cleared below and move
|
|
* the page back to the evictable list.
|
|
*
|
|
* The other side is TestClearPageMlocked().
|
|
*/
|
|
smp_mb();
|
|
}
|
|
|
|
/*
|
|
* page's status can change while we move it among lru. If an evictable
|
|
* page is on unevictable list, it never be freed. To avoid that,
|
|
* check after we added it to the list, again.
|
|
*/
|
|
if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) {
|
|
if (!isolate_lru_page(page)) {
|
|
put_page(page);
|
|
goto redo;
|
|
}
|
|
/* This means someone else dropped this page from LRU
|
|
* So, it will be freed or putback to LRU again. There is
|
|
* nothing to do here.
|
|
*/
|
|
}
|
|
|
|
if (was_unevictable && lru != LRU_UNEVICTABLE)
|
|
count_vm_event(UNEVICTABLE_PGRESCUED);
|
|
else if (!was_unevictable && lru == LRU_UNEVICTABLE)
|
|
count_vm_event(UNEVICTABLE_PGCULLED);
|
|
|
|
put_page(page); /* drop ref from isolate */
|
|
}
|
|
|
|
enum page_references {
|
|
PAGEREF_RECLAIM,
|
|
PAGEREF_RECLAIM_CLEAN,
|
|
PAGEREF_KEEP,
|
|
PAGEREF_ACTIVATE,
|
|
};
|
|
|
|
static enum page_references page_check_references(struct page *page,
|
|
struct scan_control *sc)
|
|
{
|
|
int referenced_ptes, referenced_page;
|
|
unsigned long vm_flags;
|
|
|
|
referenced_ptes = page_referenced(page, 1, sc->mem_cgroup, &vm_flags);
|
|
referenced_page = TestClearPageReferenced(page);
|
|
|
|
/* Lumpy reclaim - ignore references */
|
|
if (sc->lumpy_reclaim_mode != LUMPY_MODE_NONE)
|
|
return PAGEREF_RECLAIM;
|
|
|
|
/*
|
|
* Mlock lost the isolation race with us. Let try_to_unmap()
|
|
* move the page to the unevictable list.
|
|
*/
|
|
if (vm_flags & VM_LOCKED)
|
|
return PAGEREF_RECLAIM;
|
|
|
|
if (referenced_ptes) {
|
|
if (PageAnon(page))
|
|
return PAGEREF_ACTIVATE;
|
|
/*
|
|
* All mapped pages start out with page table
|
|
* references from the instantiating fault, so we need
|
|
* to look twice if a mapped file page is used more
|
|
* than once.
|
|
*
|
|
* Mark it and spare it for another trip around the
|
|
* inactive list. Another page table reference will
|
|
* lead to its activation.
|
|
*
|
|
* Note: the mark is set for activated pages as well
|
|
* so that recently deactivated but used pages are
|
|
* quickly recovered.
|
|
*/
|
|
SetPageReferenced(page);
|
|
|
|
if (referenced_page)
|
|
return PAGEREF_ACTIVATE;
|
|
|
|
return PAGEREF_KEEP;
|
|
}
|
|
|
|
/* Reclaim if clean, defer dirty pages to writeback */
|
|
if (referenced_page && !PageSwapBacked(page))
|
|
return PAGEREF_RECLAIM_CLEAN;
|
|
|
|
return PAGEREF_RECLAIM;
|
|
}
|
|
|
|
static noinline_for_stack void free_page_list(struct list_head *free_pages)
|
|
{
|
|
struct pagevec freed_pvec;
|
|
struct page *page, *tmp;
|
|
|
|
pagevec_init(&freed_pvec, 1);
|
|
|
|
list_for_each_entry_safe(page, tmp, free_pages, lru) {
|
|
list_del(&page->lru);
|
|
if (!pagevec_add(&freed_pvec, page)) {
|
|
__pagevec_free(&freed_pvec);
|
|
pagevec_reinit(&freed_pvec);
|
|
}
|
|
}
|
|
|
|
pagevec_free(&freed_pvec);
|
|
}
|
|
|
|
/*
|
|
* shrink_page_list() returns the number of reclaimed pages
|
|
*/
|
|
static unsigned long shrink_page_list(struct list_head *page_list,
|
|
struct zone *zone,
|
|
struct scan_control *sc)
|
|
{
|
|
LIST_HEAD(ret_pages);
|
|
LIST_HEAD(free_pages);
|
|
int pgactivate = 0;
|
|
unsigned long nr_dirty = 0;
|
|
unsigned long nr_congested = 0;
|
|
unsigned long nr_reclaimed = 0;
|
|
|
|
cond_resched();
|
|
|
|
while (!list_empty(page_list)) {
|
|
enum page_references references;
|
|
struct address_space *mapping;
|
|
struct page *page;
|
|
int may_enter_fs;
|
|
|
|
cond_resched();
|
|
|
|
page = lru_to_page(page_list);
|
|
list_del(&page->lru);
|
|
|
|
if (!trylock_page(page))
|
|
goto keep;
|
|
|
|
VM_BUG_ON(PageActive(page));
|
|
VM_BUG_ON(page_zone(page) != zone);
|
|
|
|
sc->nr_scanned++;
|
|
|
|
if (unlikely(!page_evictable(page, NULL)))
|
|
goto cull_mlocked;
|
|
|
|
if (!sc->may_unmap && page_mapped(page))
|
|
goto keep_locked;
|
|
|
|
/* Double the slab pressure for mapped and swapcache pages */
|
|
if (page_mapped(page) || PageSwapCache(page))
|
|
sc->nr_scanned++;
|
|
|
|
may_enter_fs = (sc->gfp_mask & __GFP_FS) ||
|
|
(PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
|
|
|
|
if (PageWriteback(page)) {
|
|
/*
|
|
* Synchronous reclaim is performed in two passes,
|
|
* first an asynchronous pass over the list to
|
|
* start parallel writeback, and a second synchronous
|
|
* pass to wait for the IO to complete. Wait here
|
|
* for any page for which writeback has already
|
|
* started.
|
|
*/
|
|
if (sc->lumpy_reclaim_mode == LUMPY_MODE_SYNC &&
|
|
may_enter_fs)
|
|
wait_on_page_writeback(page);
|
|
else {
|
|
unlock_page(page);
|
|
goto keep_lumpy;
|
|
}
|
|
}
|
|
|
|
references = page_check_references(page, sc);
|
|
switch (references) {
|
|
case PAGEREF_ACTIVATE:
|
|
goto activate_locked;
|
|
case PAGEREF_KEEP:
|
|
goto keep_locked;
|
|
case PAGEREF_RECLAIM:
|
|
case PAGEREF_RECLAIM_CLEAN:
|
|
; /* try to reclaim the page below */
|
|
}
|
|
|
|
/*
|
|
* Anonymous process memory has backing store?
|
|
* Try to allocate it some swap space here.
|
|
*/
|
|
if (PageAnon(page) && !PageSwapCache(page)) {
|
|
if (!(sc->gfp_mask & __GFP_IO))
|
|
goto keep_locked;
|
|
if (!add_to_swap(page))
|
|
goto activate_locked;
|
|
may_enter_fs = 1;
|
|
}
|
|
|
|
mapping = page_mapping(page);
|
|
|
|
/*
|
|
* The page is mapped into the page tables of one or more
|
|
* processes. Try to unmap it here.
|
|
*/
|
|
if (page_mapped(page) && mapping) {
|
|
switch (try_to_unmap(page, TTU_UNMAP)) {
|
|
case SWAP_FAIL:
|
|
goto activate_locked;
|
|
case SWAP_AGAIN:
|
|
goto keep_locked;
|
|
case SWAP_MLOCK:
|
|
goto cull_mlocked;
|
|
case SWAP_SUCCESS:
|
|
; /* try to free the page below */
|
|
}
|
|
}
|
|
|
|
if (PageDirty(page)) {
|
|
nr_dirty++;
|
|
|
|
if (references == PAGEREF_RECLAIM_CLEAN)
|
|
goto keep_locked;
|
|
if (!may_enter_fs)
|
|
goto keep_locked;
|
|
if (!sc->may_writepage)
|
|
goto keep_locked;
|
|
|
|
/* Page is dirty, try to write it out here */
|
|
switch (pageout(page, mapping, sc)) {
|
|
case PAGE_KEEP:
|
|
nr_congested++;
|
|
goto keep_locked;
|
|
case PAGE_ACTIVATE:
|
|
goto activate_locked;
|
|
case PAGE_SUCCESS:
|
|
if (PageWriteback(page))
|
|
goto keep_lumpy;
|
|
if (PageDirty(page))
|
|
goto keep;
|
|
|
|
/*
|
|
* A synchronous write - probably a ramdisk. Go
|
|
* ahead and try to reclaim the page.
|
|
*/
|
|
if (!trylock_page(page))
|
|
goto keep;
|
|
if (PageDirty(page) || PageWriteback(page))
|
|
goto keep_locked;
|
|
mapping = page_mapping(page);
|
|
case PAGE_CLEAN:
|
|
; /* try to free the page below */
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If the page has buffers, try to free the buffer mappings
|
|
* associated with this page. If we succeed we try to free
|
|
* the page as well.
|
|
*
|
|
* We do this even if the page is PageDirty().
|
|
* try_to_release_page() does not perform I/O, but it is
|
|
* possible for a page to have PageDirty set, but it is actually
|
|
* clean (all its buffers are clean). This happens if the
|
|
* buffers were written out directly, with submit_bh(). ext3
|
|
* will do this, as well as the blockdev mapping.
|
|
* try_to_release_page() will discover that cleanness and will
|
|
* drop the buffers and mark the page clean - it can be freed.
|
|
*
|
|
* Rarely, pages can have buffers and no ->mapping. These are
|
|
* the pages which were not successfully invalidated in
|
|
* truncate_complete_page(). We try to drop those buffers here
|
|
* and if that worked, and the page is no longer mapped into
|
|
* process address space (page_count == 1) it can be freed.
|
|
* Otherwise, leave the page on the LRU so it is swappable.
|
|
*/
|
|
if (page_has_private(page)) {
|
|
if (!try_to_release_page(page, sc->gfp_mask))
|
|
goto activate_locked;
|
|
if (!mapping && page_count(page) == 1) {
|
|
unlock_page(page);
|
|
if (put_page_testzero(page))
|
|
goto free_it;
|
|
else {
|
|
/*
|
|
* rare race with speculative reference.
|
|
* the speculative reference will free
|
|
* this page shortly, so we may
|
|
* increment nr_reclaimed here (and
|
|
* leave it off the LRU).
|
|
*/
|
|
nr_reclaimed++;
|
|
continue;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (!mapping || !__remove_mapping(mapping, page))
|
|
goto keep_locked;
|
|
|
|
/*
|
|
* At this point, we have no other references and there is
|
|
* no way to pick any more up (removed from LRU, removed
|
|
* from pagecache). Can use non-atomic bitops now (and
|
|
* we obviously don't have to worry about waking up a process
|
|
* waiting on the page lock, because there are no references.
|
|
*/
|
|
__clear_page_locked(page);
|
|
free_it:
|
|
nr_reclaimed++;
|
|
|
|
/*
|
|
* Is there need to periodically free_page_list? It would
|
|
* appear not as the counts should be low
|
|
*/
|
|
list_add(&page->lru, &free_pages);
|
|
continue;
|
|
|
|
cull_mlocked:
|
|
if (PageSwapCache(page))
|
|
try_to_free_swap(page);
|
|
unlock_page(page);
|
|
putback_lru_page(page);
|
|
disable_lumpy_reclaim_mode(sc);
|
|
continue;
|
|
|
|
activate_locked:
|
|
/* Not a candidate for swapping, so reclaim swap space. */
|
|
if (PageSwapCache(page) && vm_swap_full())
|
|
try_to_free_swap(page);
|
|
VM_BUG_ON(PageActive(page));
|
|
SetPageActive(page);
|
|
pgactivate++;
|
|
keep_locked:
|
|
unlock_page(page);
|
|
keep:
|
|
disable_lumpy_reclaim_mode(sc);
|
|
keep_lumpy:
|
|
list_add(&page->lru, &ret_pages);
|
|
VM_BUG_ON(PageLRU(page) || PageUnevictable(page));
|
|
}
|
|
|
|
/*
|
|
* Tag a zone as congested if all the dirty pages encountered were
|
|
* backed by a congested BDI. In this case, reclaimers should just
|
|
* back off and wait for congestion to clear because further reclaim
|
|
* will encounter the same problem
|
|
*/
|
|
if (nr_dirty == nr_congested && nr_dirty != 0)
|
|
zone_set_flag(zone, ZONE_CONGESTED);
|
|
|
|
free_page_list(&free_pages);
|
|
|
|
list_splice(&ret_pages, page_list);
|
|
count_vm_events(PGACTIVATE, pgactivate);
|
|
return nr_reclaimed;
|
|
}
|
|
|
|
/*
|
|
* Attempt to remove the specified page from its LRU. Only take this page
|
|
* if it is of the appropriate PageActive status. Pages which are being
|
|
* freed elsewhere are also ignored.
|
|
*
|
|
* page: page to consider
|
|
* mode: one of the LRU isolation modes defined above
|
|
*
|
|
* returns 0 on success, -ve errno on failure.
|
|
*/
|
|
int __isolate_lru_page(struct page *page, int mode, int file)
|
|
{
|
|
int ret = -EINVAL;
|
|
|
|
/* Only take pages on the LRU. */
|
|
if (!PageLRU(page))
|
|
return ret;
|
|
|
|
/*
|
|
* When checking the active state, we need to be sure we are
|
|
* dealing with comparible boolean values. Take the logical not
|
|
* of each.
|
|
*/
|
|
if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode))
|
|
return ret;
|
|
|
|
if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file)
|
|
return ret;
|
|
|
|
/*
|
|
* When this function is being called for lumpy reclaim, we
|
|
* initially look into all LRU pages, active, inactive and
|
|
* unevictable; only give shrink_page_list evictable pages.
|
|
*/
|
|
if (PageUnevictable(page))
|
|
return ret;
|
|
|
|
ret = -EBUSY;
|
|
|
|
if (likely(get_page_unless_zero(page))) {
|
|
/*
|
|
* Be careful not to clear PageLRU until after we're
|
|
* sure the page is not being freed elsewhere -- the
|
|
* page release code relies on it.
|
|
*/
|
|
ClearPageLRU(page);
|
|
ret = 0;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* zone->lru_lock is heavily contended. Some of the functions that
|
|
* shrink the lists perform better by taking out a batch of pages
|
|
* and working on them outside the LRU lock.
|
|
*
|
|
* For pagecache intensive workloads, this function is the hottest
|
|
* spot in the kernel (apart from copy_*_user functions).
|
|
*
|
|
* Appropriate locks must be held before calling this function.
|
|
*
|
|
* @nr_to_scan: The number of pages to look through on the list.
|
|
* @src: The LRU list to pull pages off.
|
|
* @dst: The temp list to put pages on to.
|
|
* @scanned: The number of pages that were scanned.
|
|
* @order: The caller's attempted allocation order
|
|
* @mode: One of the LRU isolation modes
|
|
* @file: True [1] if isolating file [!anon] pages
|
|
*
|
|
* returns how many pages were moved onto *@dst.
|
|
*/
|
|
static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
|
|
struct list_head *src, struct list_head *dst,
|
|
unsigned long *scanned, int order, int mode, int file)
|
|
{
|
|
unsigned long nr_taken = 0;
|
|
unsigned long nr_lumpy_taken = 0;
|
|
unsigned long nr_lumpy_dirty = 0;
|
|
unsigned long nr_lumpy_failed = 0;
|
|
unsigned long scan;
|
|
|
|
for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) {
|
|
struct page *page;
|
|
unsigned long pfn;
|
|
unsigned long end_pfn;
|
|
unsigned long page_pfn;
|
|
int zone_id;
|
|
|
|
page = lru_to_page(src);
|
|
prefetchw_prev_lru_page(page, src, flags);
|
|
|
|
VM_BUG_ON(!PageLRU(page));
|
|
|
|
switch (__isolate_lru_page(page, mode, file)) {
|
|
case 0:
|
|
list_move(&page->lru, dst);
|
|
mem_cgroup_del_lru(page);
|
|
nr_taken++;
|
|
break;
|
|
|
|
case -EBUSY:
|
|
/* else it is being freed elsewhere */
|
|
list_move(&page->lru, src);
|
|
mem_cgroup_rotate_lru_list(page, page_lru(page));
|
|
continue;
|
|
|
|
default:
|
|
BUG();
|
|
}
|
|
|
|
if (!order)
|
|
continue;
|
|
|
|
/*
|
|
* Attempt to take all pages in the order aligned region
|
|
* surrounding the tag page. Only take those pages of
|
|
* the same active state as that tag page. We may safely
|
|
* round the target page pfn down to the requested order
|
|
* as the mem_map is guarenteed valid out to MAX_ORDER,
|
|
* where that page is in a different zone we will detect
|
|
* it from its zone id and abort this block scan.
|
|
*/
|
|
zone_id = page_zone_id(page);
|
|
page_pfn = page_to_pfn(page);
|
|
pfn = page_pfn & ~((1 << order) - 1);
|
|
end_pfn = pfn + (1 << order);
|
|
for (; pfn < end_pfn; pfn++) {
|
|
struct page *cursor_page;
|
|
|
|
/* The target page is in the block, ignore it. */
|
|
if (unlikely(pfn == page_pfn))
|
|
continue;
|
|
|
|
/* Avoid holes within the zone. */
|
|
if (unlikely(!pfn_valid_within(pfn)))
|
|
break;
|
|
|
|
cursor_page = pfn_to_page(pfn);
|
|
|
|
/* Check that we have not crossed a zone boundary. */
|
|
if (unlikely(page_zone_id(cursor_page) != zone_id))
|
|
break;
|
|
|
|
/*
|
|
* If we don't have enough swap space, reclaiming of
|
|
* anon page which don't already have a swap slot is
|
|
* pointless.
|
|
*/
|
|
if (nr_swap_pages <= 0 && PageAnon(cursor_page) &&
|
|
!PageSwapCache(cursor_page))
|
|
break;
|
|
|
|
if (__isolate_lru_page(cursor_page, mode, file) == 0) {
|
|
list_move(&cursor_page->lru, dst);
|
|
mem_cgroup_del_lru(cursor_page);
|
|
nr_taken++;
|
|
nr_lumpy_taken++;
|
|
if (PageDirty(cursor_page))
|
|
nr_lumpy_dirty++;
|
|
scan++;
|
|
} else {
|
|
/* the page is freed already. */
|
|
if (!page_count(cursor_page))
|
|
continue;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* If we break out of the loop above, lumpy reclaim failed */
|
|
if (pfn < end_pfn)
|
|
nr_lumpy_failed++;
|
|
}
|
|
|
|
*scanned = scan;
|
|
|
|
trace_mm_vmscan_lru_isolate(order,
|
|
nr_to_scan, scan,
|
|
nr_taken,
|
|
nr_lumpy_taken, nr_lumpy_dirty, nr_lumpy_failed,
|
|
mode);
|
|
return nr_taken;
|
|
}
|
|
|
|
static unsigned long isolate_pages_global(unsigned long nr,
|
|
struct list_head *dst,
|
|
unsigned long *scanned, int order,
|
|
int mode, struct zone *z,
|
|
int active, int file)
|
|
{
|
|
int lru = LRU_BASE;
|
|
if (active)
|
|
lru += LRU_ACTIVE;
|
|
if (file)
|
|
lru += LRU_FILE;
|
|
return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order,
|
|
mode, file);
|
|
}
|
|
|
|
/*
|
|
* clear_active_flags() is a helper for shrink_active_list(), clearing
|
|
* any active bits from the pages in the list.
|
|
*/
|
|
static unsigned long clear_active_flags(struct list_head *page_list,
|
|
unsigned int *count)
|
|
{
|
|
int nr_active = 0;
|
|
int lru;
|
|
struct page *page;
|
|
|
|
list_for_each_entry(page, page_list, lru) {
|
|
lru = page_lru_base_type(page);
|
|
if (PageActive(page)) {
|
|
lru += LRU_ACTIVE;
|
|
ClearPageActive(page);
|
|
nr_active++;
|
|
}
|
|
if (count)
|
|
count[lru]++;
|
|
}
|
|
|
|
return nr_active;
|
|
}
|
|
|
|
/**
|
|
* isolate_lru_page - tries to isolate a page from its LRU list
|
|
* @page: page to isolate from its LRU list
|
|
*
|
|
* Isolates a @page from an LRU list, clears PageLRU and adjusts the
|
|
* vmstat statistic corresponding to whatever LRU list the page was on.
|
|
*
|
|
* Returns 0 if the page was removed from an LRU list.
|
|
* Returns -EBUSY if the page was not on an LRU list.
|
|
*
|
|
* The returned page will have PageLRU() cleared. If it was found on
|
|
* the active list, it will have PageActive set. If it was found on
|
|
* the unevictable list, it will have the PageUnevictable bit set. That flag
|
|
* may need to be cleared by the caller before letting the page go.
|
|
*
|
|
* The vmstat statistic corresponding to the list on which the page was
|
|
* found will be decremented.
|
|
*
|
|
* Restrictions:
|
|
* (1) Must be called with an elevated refcount on the page. This is a
|
|
* fundamentnal difference from isolate_lru_pages (which is called
|
|
* without a stable reference).
|
|
* (2) the lru_lock must not be held.
|
|
* (3) interrupts must be enabled.
|
|
*/
|
|
int isolate_lru_page(struct page *page)
|
|
{
|
|
int ret = -EBUSY;
|
|
|
|
if (PageLRU(page)) {
|
|
struct zone *zone = page_zone(page);
|
|
|
|
spin_lock_irq(&zone->lru_lock);
|
|
if (PageLRU(page) && get_page_unless_zero(page)) {
|
|
int lru = page_lru(page);
|
|
ret = 0;
|
|
ClearPageLRU(page);
|
|
|
|
del_page_from_lru_list(zone, page, lru);
|
|
}
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Are there way too many processes in the direct reclaim path already?
|
|
*/
|
|
static int too_many_isolated(struct zone *zone, int file,
|
|
struct scan_control *sc)
|
|
{
|
|
unsigned long inactive, isolated;
|
|
|
|
if (current_is_kswapd())
|
|
return 0;
|
|
|
|
if (!scanning_global_lru(sc))
|
|
return 0;
|
|
|
|
if (file) {
|
|
inactive = zone_page_state(zone, NR_INACTIVE_FILE);
|
|
isolated = zone_page_state(zone, NR_ISOLATED_FILE);
|
|
} else {
|
|
inactive = zone_page_state(zone, NR_INACTIVE_ANON);
|
|
isolated = zone_page_state(zone, NR_ISOLATED_ANON);
|
|
}
|
|
|
|
return isolated > inactive;
|
|
}
|
|
|
|
/*
|
|
* TODO: Try merging with migrations version of putback_lru_pages
|
|
*/
|
|
static noinline_for_stack void
|
|
putback_lru_pages(struct zone *zone, struct scan_control *sc,
|
|
unsigned long nr_anon, unsigned long nr_file,
|
|
struct list_head *page_list)
|
|
{
|
|
struct page *page;
|
|
struct pagevec pvec;
|
|
struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
|
|
|
|
pagevec_init(&pvec, 1);
|
|
|
|
/*
|
|
* Put back any unfreeable pages.
|
|
*/
|
|
spin_lock(&zone->lru_lock);
|
|
while (!list_empty(page_list)) {
|
|
int lru;
|
|
page = lru_to_page(page_list);
|
|
VM_BUG_ON(PageLRU(page));
|
|
list_del(&page->lru);
|
|
if (unlikely(!page_evictable(page, NULL))) {
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
putback_lru_page(page);
|
|
spin_lock_irq(&zone->lru_lock);
|
|
continue;
|
|
}
|
|
SetPageLRU(page);
|
|
lru = page_lru(page);
|
|
add_page_to_lru_list(zone, page, lru);
|
|
if (is_active_lru(lru)) {
|
|
int file = is_file_lru(lru);
|
|
reclaim_stat->recent_rotated[file]++;
|
|
}
|
|
if (!pagevec_add(&pvec, page)) {
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
__pagevec_release(&pvec);
|
|
spin_lock_irq(&zone->lru_lock);
|
|
}
|
|
}
|
|
__mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon);
|
|
__mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file);
|
|
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
pagevec_release(&pvec);
|
|
}
|
|
|
|
static noinline_for_stack void update_isolated_counts(struct zone *zone,
|
|
struct scan_control *sc,
|
|
unsigned long *nr_anon,
|
|
unsigned long *nr_file,
|
|
struct list_head *isolated_list)
|
|
{
|
|
unsigned long nr_active;
|
|
unsigned int count[NR_LRU_LISTS] = { 0, };
|
|
struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
|
|
|
|
nr_active = clear_active_flags(isolated_list, count);
|
|
__count_vm_events(PGDEACTIVATE, nr_active);
|
|
|
|
__mod_zone_page_state(zone, NR_ACTIVE_FILE,
|
|
-count[LRU_ACTIVE_FILE]);
|
|
__mod_zone_page_state(zone, NR_INACTIVE_FILE,
|
|
-count[LRU_INACTIVE_FILE]);
|
|
__mod_zone_page_state(zone, NR_ACTIVE_ANON,
|
|
-count[LRU_ACTIVE_ANON]);
|
|
__mod_zone_page_state(zone, NR_INACTIVE_ANON,
|
|
-count[LRU_INACTIVE_ANON]);
|
|
|
|
*nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON];
|
|
*nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE];
|
|
__mod_zone_page_state(zone, NR_ISOLATED_ANON, *nr_anon);
|
|
__mod_zone_page_state(zone, NR_ISOLATED_FILE, *nr_file);
|
|
|
|
reclaim_stat->recent_scanned[0] += *nr_anon;
|
|
reclaim_stat->recent_scanned[1] += *nr_file;
|
|
}
|
|
|
|
/*
|
|
* Returns true if the caller should wait to clean dirty/writeback pages.
|
|
*
|
|
* If we are direct reclaiming for contiguous pages and we do not reclaim
|
|
* everything in the list, try again and wait for writeback IO to complete.
|
|
* This will stall high-order allocations noticeably. Only do that when really
|
|
* need to free the pages under high memory pressure.
|
|
*/
|
|
static inline bool should_reclaim_stall(unsigned long nr_taken,
|
|
unsigned long nr_freed,
|
|
int priority,
|
|
struct scan_control *sc)
|
|
{
|
|
int lumpy_stall_priority;
|
|
|
|
/* kswapd should not stall on sync IO */
|
|
if (current_is_kswapd())
|
|
return false;
|
|
|
|
/* Only stall on lumpy reclaim */
|
|
if (sc->lumpy_reclaim_mode == LUMPY_MODE_NONE)
|
|
return false;
|
|
|
|
/* If we have relaimed everything on the isolated list, no stall */
|
|
if (nr_freed == nr_taken)
|
|
return false;
|
|
|
|
/*
|
|
* For high-order allocations, there are two stall thresholds.
|
|
* High-cost allocations stall immediately where as lower
|
|
* order allocations such as stacks require the scanning
|
|
* priority to be much higher before stalling.
|
|
*/
|
|
if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
|
|
lumpy_stall_priority = DEF_PRIORITY;
|
|
else
|
|
lumpy_stall_priority = DEF_PRIORITY / 3;
|
|
|
|
return priority <= lumpy_stall_priority;
|
|
}
|
|
|
|
/*
|
|
* shrink_inactive_list() is a helper for shrink_zone(). It returns the number
|
|
* of reclaimed pages
|
|
*/
|
|
static noinline_for_stack unsigned long
|
|
shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
|
|
struct scan_control *sc, int priority, int file)
|
|
{
|
|
LIST_HEAD(page_list);
|
|
unsigned long nr_scanned;
|
|
unsigned long nr_reclaimed = 0;
|
|
unsigned long nr_taken;
|
|
unsigned long nr_anon;
|
|
unsigned long nr_file;
|
|
|
|
while (unlikely(too_many_isolated(zone, file, sc))) {
|
|
congestion_wait(BLK_RW_ASYNC, HZ/10);
|
|
|
|
/* We are about to die and free our memory. Return now. */
|
|
if (fatal_signal_pending(current))
|
|
return SWAP_CLUSTER_MAX;
|
|
}
|
|
|
|
set_lumpy_reclaim_mode(priority, sc, false);
|
|
lru_add_drain();
|
|
spin_lock_irq(&zone->lru_lock);
|
|
|
|
if (scanning_global_lru(sc)) {
|
|
nr_taken = isolate_pages_global(nr_to_scan,
|
|
&page_list, &nr_scanned, sc->order,
|
|
sc->lumpy_reclaim_mode == LUMPY_MODE_NONE ?
|
|
ISOLATE_INACTIVE : ISOLATE_BOTH,
|
|
zone, 0, file);
|
|
zone->pages_scanned += nr_scanned;
|
|
if (current_is_kswapd())
|
|
__count_zone_vm_events(PGSCAN_KSWAPD, zone,
|
|
nr_scanned);
|
|
else
|
|
__count_zone_vm_events(PGSCAN_DIRECT, zone,
|
|
nr_scanned);
|
|
} else {
|
|
nr_taken = mem_cgroup_isolate_pages(nr_to_scan,
|
|
&page_list, &nr_scanned, sc->order,
|
|
sc->lumpy_reclaim_mode == LUMPY_MODE_NONE ?
|
|
ISOLATE_INACTIVE : ISOLATE_BOTH,
|
|
zone, sc->mem_cgroup,
|
|
0, file);
|
|
/*
|
|
* mem_cgroup_isolate_pages() keeps track of
|
|
* scanned pages on its own.
|
|
*/
|
|
}
|
|
|
|
if (nr_taken == 0) {
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
return 0;
|
|
}
|
|
|
|
update_isolated_counts(zone, sc, &nr_anon, &nr_file, &page_list);
|
|
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
|
|
nr_reclaimed = shrink_page_list(&page_list, zone, sc);
|
|
|
|
/* Check if we should syncronously wait for writeback */
|
|
if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) {
|
|
set_lumpy_reclaim_mode(priority, sc, true);
|
|
nr_reclaimed += shrink_page_list(&page_list, zone, sc);
|
|
}
|
|
|
|
local_irq_disable();
|
|
if (current_is_kswapd())
|
|
__count_vm_events(KSWAPD_STEAL, nr_reclaimed);
|
|
__count_zone_vm_events(PGSTEAL, zone, nr_reclaimed);
|
|
|
|
putback_lru_pages(zone, sc, nr_anon, nr_file, &page_list);
|
|
|
|
trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id,
|
|
zone_idx(zone),
|
|
nr_scanned, nr_reclaimed,
|
|
priority,
|
|
trace_shrink_flags(file, sc->lumpy_reclaim_mode));
|
|
return nr_reclaimed;
|
|
}
|
|
|
|
/*
|
|
* This moves pages from the active list to the inactive list.
|
|
*
|
|
* We move them the other way if the page is referenced by one or more
|
|
* processes, from rmap.
|
|
*
|
|
* If the pages are mostly unmapped, the processing is fast and it is
|
|
* appropriate to hold zone->lru_lock across the whole operation. But if
|
|
* the pages are mapped, the processing is slow (page_referenced()) so we
|
|
* should drop zone->lru_lock around each page. It's impossible to balance
|
|
* this, so instead we remove the pages from the LRU while processing them.
|
|
* It is safe to rely on PG_active against the non-LRU pages in here because
|
|
* nobody will play with that bit on a non-LRU page.
|
|
*
|
|
* The downside is that we have to touch page->_count against each page.
|
|
* But we had to alter page->flags anyway.
|
|
*/
|
|
|
|
static void move_active_pages_to_lru(struct zone *zone,
|
|
struct list_head *list,
|
|
enum lru_list lru)
|
|
{
|
|
unsigned long pgmoved = 0;
|
|
struct pagevec pvec;
|
|
struct page *page;
|
|
|
|
pagevec_init(&pvec, 1);
|
|
|
|
while (!list_empty(list)) {
|
|
page = lru_to_page(list);
|
|
|
|
VM_BUG_ON(PageLRU(page));
|
|
SetPageLRU(page);
|
|
|
|
list_move(&page->lru, &zone->lru[lru].list);
|
|
mem_cgroup_add_lru_list(page, lru);
|
|
pgmoved++;
|
|
|
|
if (!pagevec_add(&pvec, page) || list_empty(list)) {
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
if (buffer_heads_over_limit)
|
|
pagevec_strip(&pvec);
|
|
__pagevec_release(&pvec);
|
|
spin_lock_irq(&zone->lru_lock);
|
|
}
|
|
}
|
|
__mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
|
|
if (!is_active_lru(lru))
|
|
__count_vm_events(PGDEACTIVATE, pgmoved);
|
|
}
|
|
|
|
static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
|
|
struct scan_control *sc, int priority, int file)
|
|
{
|
|
unsigned long nr_taken;
|
|
unsigned long pgscanned;
|
|
unsigned long vm_flags;
|
|
LIST_HEAD(l_hold); /* The pages which were snipped off */
|
|
LIST_HEAD(l_active);
|
|
LIST_HEAD(l_inactive);
|
|
struct page *page;
|
|
struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
|
|
unsigned long nr_rotated = 0;
|
|
|
|
lru_add_drain();
|
|
spin_lock_irq(&zone->lru_lock);
|
|
if (scanning_global_lru(sc)) {
|
|
nr_taken = isolate_pages_global(nr_pages, &l_hold,
|
|
&pgscanned, sc->order,
|
|
ISOLATE_ACTIVE, zone,
|
|
1, file);
|
|
zone->pages_scanned += pgscanned;
|
|
} else {
|
|
nr_taken = mem_cgroup_isolate_pages(nr_pages, &l_hold,
|
|
&pgscanned, sc->order,
|
|
ISOLATE_ACTIVE, zone,
|
|
sc->mem_cgroup, 1, file);
|
|
/*
|
|
* mem_cgroup_isolate_pages() keeps track of
|
|
* scanned pages on its own.
|
|
*/
|
|
}
|
|
|
|
reclaim_stat->recent_scanned[file] += nr_taken;
|
|
|
|
__count_zone_vm_events(PGREFILL, zone, pgscanned);
|
|
if (file)
|
|
__mod_zone_page_state(zone, NR_ACTIVE_FILE, -nr_taken);
|
|
else
|
|
__mod_zone_page_state(zone, NR_ACTIVE_ANON, -nr_taken);
|
|
__mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken);
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
|
|
while (!list_empty(&l_hold)) {
|
|
cond_resched();
|
|
page = lru_to_page(&l_hold);
|
|
list_del(&page->lru);
|
|
|
|
if (unlikely(!page_evictable(page, NULL))) {
|
|
putback_lru_page(page);
|
|
continue;
|
|
}
|
|
|
|
if (page_referenced(page, 0, sc->mem_cgroup, &vm_flags)) {
|
|
nr_rotated++;
|
|
/*
|
|
* Identify referenced, file-backed active pages and
|
|
* give them one more trip around the active list. So
|
|
* that executable code get better chances to stay in
|
|
* memory under moderate memory pressure. Anon pages
|
|
* are not likely to be evicted by use-once streaming
|
|
* IO, plus JVM can create lots of anon VM_EXEC pages,
|
|
* so we ignore them here.
|
|
*/
|
|
if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) {
|
|
list_add(&page->lru, &l_active);
|
|
continue;
|
|
}
|
|
}
|
|
|
|
ClearPageActive(page); /* we are de-activating */
|
|
list_add(&page->lru, &l_inactive);
|
|
}
|
|
|
|
/*
|
|
* Move pages back to the lru list.
|
|
*/
|
|
spin_lock_irq(&zone->lru_lock);
|
|
/*
|
|
* Count referenced pages from currently used mappings as rotated,
|
|
* even though only some of them are actually re-activated. This
|
|
* helps balance scan pressure between file and anonymous pages in
|
|
* get_scan_ratio.
|
|
*/
|
|
reclaim_stat->recent_rotated[file] += nr_rotated;
|
|
|
|
move_active_pages_to_lru(zone, &l_active,
|
|
LRU_ACTIVE + file * LRU_FILE);
|
|
move_active_pages_to_lru(zone, &l_inactive,
|
|
LRU_BASE + file * LRU_FILE);
|
|
__mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken);
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
}
|
|
|
|
#ifdef CONFIG_SWAP
|
|
static int inactive_anon_is_low_global(struct zone *zone)
|
|
{
|
|
unsigned long active, inactive;
|
|
|
|
active = zone_page_state(zone, NR_ACTIVE_ANON);
|
|
inactive = zone_page_state(zone, NR_INACTIVE_ANON);
|
|
|
|
if (inactive * zone->inactive_ratio < active)
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* inactive_anon_is_low - check if anonymous pages need to be deactivated
|
|
* @zone: zone to check
|
|
* @sc: scan control of this context
|
|
*
|
|
* Returns true if the zone does not have enough inactive anon pages,
|
|
* meaning some active anon pages need to be deactivated.
|
|
*/
|
|
static int inactive_anon_is_low(struct zone *zone, struct scan_control *sc)
|
|
{
|
|
int low;
|
|
|
|
/*
|
|
* If we don't have swap space, anonymous page deactivation
|
|
* is pointless.
|
|
*/
|
|
if (!total_swap_pages)
|
|
return 0;
|
|
|
|
if (scanning_global_lru(sc))
|
|
low = inactive_anon_is_low_global(zone);
|
|
else
|
|
low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup);
|
|
return low;
|
|
}
|
|
#else
|
|
static inline int inactive_anon_is_low(struct zone *zone,
|
|
struct scan_control *sc)
|
|
{
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
static int inactive_file_is_low_global(struct zone *zone)
|
|
{
|
|
unsigned long active, inactive;
|
|
|
|
active = zone_page_state(zone, NR_ACTIVE_FILE);
|
|
inactive = zone_page_state(zone, NR_INACTIVE_FILE);
|
|
|
|
return (active > inactive);
|
|
}
|
|
|
|
/**
|
|
* inactive_file_is_low - check if file pages need to be deactivated
|
|
* @zone: zone to check
|
|
* @sc: scan control of this context
|
|
*
|
|
* When the system is doing streaming IO, memory pressure here
|
|
* ensures that active file pages get deactivated, until more
|
|
* than half of the file pages are on the inactive list.
|
|
*
|
|
* Once we get to that situation, protect the system's working
|
|
* set from being evicted by disabling active file page aging.
|
|
*
|
|
* This uses a different ratio than the anonymous pages, because
|
|
* the page cache uses a use-once replacement algorithm.
|
|
*/
|
|
static int inactive_file_is_low(struct zone *zone, struct scan_control *sc)
|
|
{
|
|
int low;
|
|
|
|
if (scanning_global_lru(sc))
|
|
low = inactive_file_is_low_global(zone);
|
|
else
|
|
low = mem_cgroup_inactive_file_is_low(sc->mem_cgroup);
|
|
return low;
|
|
}
|
|
|
|
static int inactive_list_is_low(struct zone *zone, struct scan_control *sc,
|
|
int file)
|
|
{
|
|
if (file)
|
|
return inactive_file_is_low(zone, sc);
|
|
else
|
|
return inactive_anon_is_low(zone, sc);
|
|
}
|
|
|
|
static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
|
|
struct zone *zone, struct scan_control *sc, int priority)
|
|
{
|
|
int file = is_file_lru(lru);
|
|
|
|
if (is_active_lru(lru)) {
|
|
if (inactive_list_is_low(zone, sc, file))
|
|
shrink_active_list(nr_to_scan, zone, sc, priority, file);
|
|
return 0;
|
|
}
|
|
|
|
return shrink_inactive_list(nr_to_scan, zone, sc, priority, file);
|
|
}
|
|
|
|
/*
|
|
* Smallish @nr_to_scan's are deposited in @nr_saved_scan,
|
|
* until we collected @swap_cluster_max pages to scan.
|
|
*/
|
|
static unsigned long nr_scan_try_batch(unsigned long nr_to_scan,
|
|
unsigned long *nr_saved_scan)
|
|
{
|
|
unsigned long nr;
|
|
|
|
*nr_saved_scan += nr_to_scan;
|
|
nr = *nr_saved_scan;
|
|
|
|
if (nr >= SWAP_CLUSTER_MAX)
|
|
*nr_saved_scan = 0;
|
|
else
|
|
nr = 0;
|
|
|
|
return nr;
|
|
}
|
|
|
|
/*
|
|
* Determine how aggressively the anon and file LRU lists should be
|
|
* scanned. The relative value of each set of LRU lists is determined
|
|
* by looking at the fraction of the pages scanned we did rotate back
|
|
* onto the active list instead of evict.
|
|
*
|
|
* nr[0] = anon pages to scan; nr[1] = file pages to scan
|
|
*/
|
|
static void get_scan_count(struct zone *zone, struct scan_control *sc,
|
|
unsigned long *nr, int priority)
|
|
{
|
|
unsigned long anon, file, free;
|
|
unsigned long anon_prio, file_prio;
|
|
unsigned long ap, fp;
|
|
struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
|
|
u64 fraction[2], denominator;
|
|
enum lru_list l;
|
|
int noswap = 0;
|
|
|
|
/* If we have no swap space, do not bother scanning anon pages. */
|
|
if (!sc->may_swap || (nr_swap_pages <= 0)) {
|
|
noswap = 1;
|
|
fraction[0] = 0;
|
|
fraction[1] = 1;
|
|
denominator = 1;
|
|
goto out;
|
|
}
|
|
|
|
anon = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) +
|
|
zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON);
|
|
file = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) +
|
|
zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE);
|
|
|
|
if (scanning_global_lru(sc)) {
|
|
free = zone_page_state(zone, NR_FREE_PAGES);
|
|
/* If we have very few page cache pages,
|
|
force-scan anon pages. */
|
|
if (unlikely(file + free <= high_wmark_pages(zone))) {
|
|
fraction[0] = 1;
|
|
fraction[1] = 0;
|
|
denominator = 1;
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* With swappiness at 100, anonymous and file have the same priority.
|
|
* This scanning priority is essentially the inverse of IO cost.
|
|
*/
|
|
anon_prio = sc->swappiness;
|
|
file_prio = 200 - sc->swappiness;
|
|
|
|
/*
|
|
* OK, so we have swap space and a fair amount of page cache
|
|
* pages. We use the recently rotated / recently scanned
|
|
* ratios to determine how valuable each cache is.
|
|
*
|
|
* Because workloads change over time (and to avoid overflow)
|
|
* we keep these statistics as a floating average, which ends
|
|
* up weighing recent references more than old ones.
|
|
*
|
|
* anon in [0], file in [1]
|
|
*/
|
|
spin_lock_irq(&zone->lru_lock);
|
|
if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) {
|
|
reclaim_stat->recent_scanned[0] /= 2;
|
|
reclaim_stat->recent_rotated[0] /= 2;
|
|
}
|
|
|
|
if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) {
|
|
reclaim_stat->recent_scanned[1] /= 2;
|
|
reclaim_stat->recent_rotated[1] /= 2;
|
|
}
|
|
|
|
/*
|
|
* The amount of pressure on anon vs file pages is inversely
|
|
* proportional to the fraction of recently scanned pages on
|
|
* each list that were recently referenced and in active use.
|
|
*/
|
|
ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1);
|
|
ap /= reclaim_stat->recent_rotated[0] + 1;
|
|
|
|
fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1);
|
|
fp /= reclaim_stat->recent_rotated[1] + 1;
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
|
|
fraction[0] = ap;
|
|
fraction[1] = fp;
|
|
denominator = ap + fp + 1;
|
|
out:
|
|
for_each_evictable_lru(l) {
|
|
int file = is_file_lru(l);
|
|
unsigned long scan;
|
|
|
|
scan = zone_nr_lru_pages(zone, sc, l);
|
|
if (priority || noswap) {
|
|
scan >>= priority;
|
|
scan = div64_u64(scan * fraction[file], denominator);
|
|
}
|
|
nr[l] = nr_scan_try_batch(scan,
|
|
&reclaim_stat->nr_saved_scan[l]);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* This is a basic per-zone page freer. Used by both kswapd and direct reclaim.
|
|
*/
|
|
static void shrink_zone(int priority, struct zone *zone,
|
|
struct scan_control *sc)
|
|
{
|
|
unsigned long nr[NR_LRU_LISTS];
|
|
unsigned long nr_to_scan;
|
|
enum lru_list l;
|
|
unsigned long nr_reclaimed = sc->nr_reclaimed;
|
|
unsigned long nr_to_reclaim = sc->nr_to_reclaim;
|
|
|
|
get_scan_count(zone, sc, nr, priority);
|
|
|
|
while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
|
|
nr[LRU_INACTIVE_FILE]) {
|
|
for_each_evictable_lru(l) {
|
|
if (nr[l]) {
|
|
nr_to_scan = min_t(unsigned long,
|
|
nr[l], SWAP_CLUSTER_MAX);
|
|
nr[l] -= nr_to_scan;
|
|
|
|
nr_reclaimed += shrink_list(l, nr_to_scan,
|
|
zone, sc, priority);
|
|
}
|
|
}
|
|
/*
|
|
* On large memory systems, scan >> priority can become
|
|
* really large. This is fine for the starting priority;
|
|
* we want to put equal scanning pressure on each zone.
|
|
* However, if the VM has a harder time of freeing pages,
|
|
* with multiple processes reclaiming pages, the total
|
|
* freeing target can get unreasonably large.
|
|
*/
|
|
if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY)
|
|
break;
|
|
}
|
|
|
|
sc->nr_reclaimed = nr_reclaimed;
|
|
|
|
/*
|
|
* Even if we did not try to evict anon pages at all, we want to
|
|
* rebalance the anon lru active/inactive ratio.
|
|
*/
|
|
if (inactive_anon_is_low(zone, sc))
|
|
shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0);
|
|
|
|
throttle_vm_writeout(sc->gfp_mask);
|
|
}
|
|
|
|
/*
|
|
* This is the direct reclaim path, for page-allocating processes. We only
|
|
* try to reclaim pages from zones which will satisfy the caller's allocation
|
|
* request.
|
|
*
|
|
* We reclaim from a zone even if that zone is over high_wmark_pages(zone).
|
|
* Because:
|
|
* a) The caller may be trying to free *extra* pages to satisfy a higher-order
|
|
* allocation or
|
|
* b) The target zone may be at high_wmark_pages(zone) but the lower zones
|
|
* must go *over* high_wmark_pages(zone) to satisfy the `incremental min'
|
|
* zone defense algorithm.
|
|
*
|
|
* If a zone is deemed to be full of pinned pages then just give it a light
|
|
* scan then give up on it.
|
|
*/
|
|
static void shrink_zones(int priority, struct zonelist *zonelist,
|
|
struct scan_control *sc)
|
|
{
|
|
struct zoneref *z;
|
|
struct zone *zone;
|
|
|
|
for_each_zone_zonelist_nodemask(zone, z, zonelist,
|
|
gfp_zone(sc->gfp_mask), sc->nodemask) {
|
|
if (!populated_zone(zone))
|
|
continue;
|
|
/*
|
|
* Take care memory controller reclaiming has small influence
|
|
* to global LRU.
|
|
*/
|
|
if (scanning_global_lru(sc)) {
|
|
if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
|
|
continue;
|
|
if (zone->all_unreclaimable && priority != DEF_PRIORITY)
|
|
continue; /* Let kswapd poll it */
|
|
}
|
|
|
|
shrink_zone(priority, zone, sc);
|
|
}
|
|
}
|
|
|
|
static bool zone_reclaimable(struct zone *zone)
|
|
{
|
|
return zone->pages_scanned < zone_reclaimable_pages(zone) * 6;
|
|
}
|
|
|
|
/*
|
|
* As hibernation is going on, kswapd is freezed so that it can't mark
|
|
* the zone into all_unreclaimable. It can't handle OOM during hibernation.
|
|
* So let's check zone's unreclaimable in direct reclaim as well as kswapd.
|
|
*/
|
|
static bool all_unreclaimable(struct zonelist *zonelist,
|
|
struct scan_control *sc)
|
|
{
|
|
struct zoneref *z;
|
|
struct zone *zone;
|
|
bool all_unreclaimable = true;
|
|
|
|
for_each_zone_zonelist_nodemask(zone, z, zonelist,
|
|
gfp_zone(sc->gfp_mask), sc->nodemask) {
|
|
if (!populated_zone(zone))
|
|
continue;
|
|
if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
|
|
continue;
|
|
if (zone_reclaimable(zone)) {
|
|
all_unreclaimable = false;
|
|
break;
|
|
}
|
|
}
|
|
|
|
return all_unreclaimable;
|
|
}
|
|
|
|
/*
|
|
* This is the main entry point to direct page reclaim.
|
|
*
|
|
* If a full scan of the inactive list fails to free enough memory then we
|
|
* are "out of memory" and something needs to be killed.
|
|
*
|
|
* If the caller is !__GFP_FS then the probability of a failure is reasonably
|
|
* high - the zone may be full of dirty or under-writeback pages, which this
|
|
* caller can't do much about. We kick the writeback threads and take explicit
|
|
* naps in the hope that some of these pages can be written. But if the
|
|
* allocating task holds filesystem locks which prevent writeout this might not
|
|
* work, and the allocation attempt will fail.
|
|
*
|
|
* returns: 0, if no pages reclaimed
|
|
* else, the number of pages reclaimed
|
|
*/
|
|
static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
|
|
struct scan_control *sc)
|
|
{
|
|
int priority;
|
|
unsigned long total_scanned = 0;
|
|
struct reclaim_state *reclaim_state = current->reclaim_state;
|
|
struct zoneref *z;
|
|
struct zone *zone;
|
|
unsigned long writeback_threshold;
|
|
|
|
get_mems_allowed();
|
|
delayacct_freepages_start();
|
|
|
|
if (scanning_global_lru(sc))
|
|
count_vm_event(ALLOCSTALL);
|
|
|
|
for (priority = DEF_PRIORITY; priority >= 0; priority--) {
|
|
sc->nr_scanned = 0;
|
|
if (!priority)
|
|
disable_swap_token();
|
|
shrink_zones(priority, zonelist, sc);
|
|
/*
|
|
* Don't shrink slabs when reclaiming memory from
|
|
* over limit cgroups
|
|
*/
|
|
if (scanning_global_lru(sc)) {
|
|
unsigned long lru_pages = 0;
|
|
for_each_zone_zonelist(zone, z, zonelist,
|
|
gfp_zone(sc->gfp_mask)) {
|
|
if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
|
|
continue;
|
|
|
|
lru_pages += zone_reclaimable_pages(zone);
|
|
}
|
|
|
|
shrink_slab(sc->nr_scanned, sc->gfp_mask, lru_pages);
|
|
if (reclaim_state) {
|
|
sc->nr_reclaimed += reclaim_state->reclaimed_slab;
|
|
reclaim_state->reclaimed_slab = 0;
|
|
}
|
|
}
|
|
total_scanned += sc->nr_scanned;
|
|
if (sc->nr_reclaimed >= sc->nr_to_reclaim)
|
|
goto out;
|
|
|
|
/*
|
|
* Try to write back as many pages as we just scanned. This
|
|
* tends to cause slow streaming writers to write data to the
|
|
* disk smoothly, at the dirtying rate, which is nice. But
|
|
* that's undesirable in laptop mode, where we *want* lumpy
|
|
* writeout. So in laptop mode, write out the whole world.
|
|
*/
|
|
writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2;
|
|
if (total_scanned > writeback_threshold) {
|
|
wakeup_flusher_threads(laptop_mode ? 0 : total_scanned);
|
|
sc->may_writepage = 1;
|
|
}
|
|
|
|
/* Take a nap, wait for some writeback to complete */
|
|
if (!sc->hibernation_mode && sc->nr_scanned &&
|
|
priority < DEF_PRIORITY - 2) {
|
|
struct zone *preferred_zone;
|
|
|
|
first_zones_zonelist(zonelist, gfp_zone(sc->gfp_mask),
|
|
NULL, &preferred_zone);
|
|
wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/10);
|
|
}
|
|
}
|
|
|
|
out:
|
|
delayacct_freepages_end();
|
|
put_mems_allowed();
|
|
|
|
if (sc->nr_reclaimed)
|
|
return sc->nr_reclaimed;
|
|
|
|
/* top priority shrink_zones still had more to do? don't OOM, then */
|
|
if (scanning_global_lru(sc) && !all_unreclaimable(zonelist, sc))
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
|
|
gfp_t gfp_mask, nodemask_t *nodemask)
|
|
{
|
|
unsigned long nr_reclaimed;
|
|
struct scan_control sc = {
|
|
.gfp_mask = gfp_mask,
|
|
.may_writepage = !laptop_mode,
|
|
.nr_to_reclaim = SWAP_CLUSTER_MAX,
|
|
.may_unmap = 1,
|
|
.may_swap = 1,
|
|
.swappiness = vm_swappiness,
|
|
.order = order,
|
|
.mem_cgroup = NULL,
|
|
.nodemask = nodemask,
|
|
};
|
|
|
|
trace_mm_vmscan_direct_reclaim_begin(order,
|
|
sc.may_writepage,
|
|
gfp_mask);
|
|
|
|
nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
|
|
|
|
trace_mm_vmscan_direct_reclaim_end(nr_reclaimed);
|
|
|
|
return nr_reclaimed;
|
|
}
|
|
|
|
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
|
|
|
|
unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
|
|
gfp_t gfp_mask, bool noswap,
|
|
unsigned int swappiness,
|
|
struct zone *zone)
|
|
{
|
|
struct scan_control sc = {
|
|
.nr_to_reclaim = SWAP_CLUSTER_MAX,
|
|
.may_writepage = !laptop_mode,
|
|
.may_unmap = 1,
|
|
.may_swap = !noswap,
|
|
.swappiness = swappiness,
|
|
.order = 0,
|
|
.mem_cgroup = mem,
|
|
};
|
|
sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
|
|
(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
|
|
|
|
trace_mm_vmscan_memcg_softlimit_reclaim_begin(0,
|
|
sc.may_writepage,
|
|
sc.gfp_mask);
|
|
|
|
/*
|
|
* NOTE: Although we can get the priority field, using it
|
|
* here is not a good idea, since it limits the pages we can scan.
|
|
* if we don't reclaim here, the shrink_zone from balance_pgdat
|
|
* will pick up pages from other mem cgroup's as well. We hack
|
|
* the priority and make it zero.
|
|
*/
|
|
shrink_zone(0, zone, &sc);
|
|
|
|
trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
|
|
|
|
return sc.nr_reclaimed;
|
|
}
|
|
|
|
unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont,
|
|
gfp_t gfp_mask,
|
|
bool noswap,
|
|
unsigned int swappiness)
|
|
{
|
|
struct zonelist *zonelist;
|
|
unsigned long nr_reclaimed;
|
|
struct scan_control sc = {
|
|
.may_writepage = !laptop_mode,
|
|
.may_unmap = 1,
|
|
.may_swap = !noswap,
|
|
.nr_to_reclaim = SWAP_CLUSTER_MAX,
|
|
.swappiness = swappiness,
|
|
.order = 0,
|
|
.mem_cgroup = mem_cont,
|
|
.nodemask = NULL, /* we don't care the placement */
|
|
};
|
|
|
|
sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
|
|
(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
|
|
zonelist = NODE_DATA(numa_node_id())->node_zonelists;
|
|
|
|
trace_mm_vmscan_memcg_reclaim_begin(0,
|
|
sc.may_writepage,
|
|
sc.gfp_mask);
|
|
|
|
nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
|
|
|
|
trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed);
|
|
|
|
return nr_reclaimed;
|
|
}
|
|
#endif
|
|
|
|
/* is kswapd sleeping prematurely? */
|
|
static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining)
|
|
{
|
|
int i;
|
|
|
|
/* If a direct reclaimer woke kswapd within HZ/10, it's premature */
|
|
if (remaining)
|
|
return 1;
|
|
|
|
/* If after HZ/10, a zone is below the high mark, it's premature */
|
|
for (i = 0; i < pgdat->nr_zones; i++) {
|
|
struct zone *zone = pgdat->node_zones + i;
|
|
|
|
if (!populated_zone(zone))
|
|
continue;
|
|
|
|
if (zone->all_unreclaimable)
|
|
continue;
|
|
|
|
if (!zone_watermark_ok(zone, order, high_wmark_pages(zone),
|
|
0, 0))
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* For kswapd, balance_pgdat() will work across all this node's zones until
|
|
* they are all at high_wmark_pages(zone).
|
|
*
|
|
* Returns the number of pages which were actually freed.
|
|
*
|
|
* There is special handling here for zones which are full of pinned pages.
|
|
* This can happen if the pages are all mlocked, or if they are all used by
|
|
* device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb.
|
|
* What we do is to detect the case where all pages in the zone have been
|
|
* scanned twice and there has been zero successful reclaim. Mark the zone as
|
|
* dead and from now on, only perform a short scan. Basically we're polling
|
|
* the zone for when the problem goes away.
|
|
*
|
|
* kswapd scans the zones in the highmem->normal->dma direction. It skips
|
|
* zones which have free_pages > high_wmark_pages(zone), but once a zone is
|
|
* found to have free_pages <= high_wmark_pages(zone), we scan that zone and the
|
|
* lower zones regardless of the number of free pages in the lower zones. This
|
|
* interoperates with the page allocator fallback scheme to ensure that aging
|
|
* of pages is balanced across the zones.
|
|
*/
|
|
static unsigned long balance_pgdat(pg_data_t *pgdat, int order)
|
|
{
|
|
int all_zones_ok;
|
|
int priority;
|
|
int i;
|
|
unsigned long total_scanned;
|
|
struct reclaim_state *reclaim_state = current->reclaim_state;
|
|
struct scan_control sc = {
|
|
.gfp_mask = GFP_KERNEL,
|
|
.may_unmap = 1,
|
|
.may_swap = 1,
|
|
/*
|
|
* kswapd doesn't want to be bailed out while reclaim. because
|
|
* we want to put equal scanning pressure on each zone.
|
|
*/
|
|
.nr_to_reclaim = ULONG_MAX,
|
|
.swappiness = vm_swappiness,
|
|
.order = order,
|
|
.mem_cgroup = NULL,
|
|
};
|
|
loop_again:
|
|
total_scanned = 0;
|
|
sc.nr_reclaimed = 0;
|
|
sc.may_writepage = !laptop_mode;
|
|
count_vm_event(PAGEOUTRUN);
|
|
|
|
for (priority = DEF_PRIORITY; priority >= 0; priority--) {
|
|
int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
|
|
unsigned long lru_pages = 0;
|
|
int has_under_min_watermark_zone = 0;
|
|
|
|
/* The swap token gets in the way of swapout... */
|
|
if (!priority)
|
|
disable_swap_token();
|
|
|
|
all_zones_ok = 1;
|
|
|
|
/*
|
|
* Scan in the highmem->dma direction for the highest
|
|
* zone which needs scanning
|
|
*/
|
|
for (i = pgdat->nr_zones - 1; i >= 0; i--) {
|
|
struct zone *zone = pgdat->node_zones + i;
|
|
|
|
if (!populated_zone(zone))
|
|
continue;
|
|
|
|
if (zone->all_unreclaimable && priority != DEF_PRIORITY)
|
|
continue;
|
|
|
|
/*
|
|
* Do some background aging of the anon list, to give
|
|
* pages a chance to be referenced before reclaiming.
|
|
*/
|
|
if (inactive_anon_is_low(zone, &sc))
|
|
shrink_active_list(SWAP_CLUSTER_MAX, zone,
|
|
&sc, priority, 0);
|
|
|
|
if (!zone_watermark_ok(zone, order,
|
|
high_wmark_pages(zone), 0, 0)) {
|
|
end_zone = i;
|
|
break;
|
|
}
|
|
}
|
|
if (i < 0)
|
|
goto out;
|
|
|
|
for (i = 0; i <= end_zone; i++) {
|
|
struct zone *zone = pgdat->node_zones + i;
|
|
|
|
lru_pages += zone_reclaimable_pages(zone);
|
|
}
|
|
|
|
/*
|
|
* Now scan the zone in the dma->highmem direction, stopping
|
|
* at the last zone which needs scanning.
|
|
*
|
|
* We do this because the page allocator works in the opposite
|
|
* direction. This prevents the page allocator from allocating
|
|
* pages behind kswapd's direction of progress, which would
|
|
* cause too much scanning of the lower zones.
|
|
*/
|
|
for (i = 0; i <= end_zone; i++) {
|
|
struct zone *zone = pgdat->node_zones + i;
|
|
int nr_slab;
|
|
|
|
if (!populated_zone(zone))
|
|
continue;
|
|
|
|
if (zone->all_unreclaimable && priority != DEF_PRIORITY)
|
|
continue;
|
|
|
|
sc.nr_scanned = 0;
|
|
|
|
/*
|
|
* Call soft limit reclaim before calling shrink_zone.
|
|
* For now we ignore the return value
|
|
*/
|
|
mem_cgroup_soft_limit_reclaim(zone, order, sc.gfp_mask);
|
|
|
|
/*
|
|
* We put equal pressure on every zone, unless one
|
|
* zone has way too many pages free already.
|
|
*/
|
|
if (!zone_watermark_ok(zone, order,
|
|
8*high_wmark_pages(zone), end_zone, 0))
|
|
shrink_zone(priority, zone, &sc);
|
|
reclaim_state->reclaimed_slab = 0;
|
|
nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,
|
|
lru_pages);
|
|
sc.nr_reclaimed += reclaim_state->reclaimed_slab;
|
|
total_scanned += sc.nr_scanned;
|
|
if (zone->all_unreclaimable)
|
|
continue;
|
|
if (nr_slab == 0 && !zone_reclaimable(zone))
|
|
zone->all_unreclaimable = 1;
|
|
/*
|
|
* If we've done a decent amount of scanning and
|
|
* the reclaim ratio is low, start doing writepage
|
|
* even in laptop mode
|
|
*/
|
|
if (total_scanned > SWAP_CLUSTER_MAX * 2 &&
|
|
total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2)
|
|
sc.may_writepage = 1;
|
|
|
|
if (!zone_watermark_ok(zone, order,
|
|
high_wmark_pages(zone), end_zone, 0)) {
|
|
all_zones_ok = 0;
|
|
/*
|
|
* We are still under min water mark. This
|
|
* means that we have a GFP_ATOMIC allocation
|
|
* failure risk. Hurry up!
|
|
*/
|
|
if (!zone_watermark_ok(zone, order,
|
|
min_wmark_pages(zone), end_zone, 0))
|
|
has_under_min_watermark_zone = 1;
|
|
} else {
|
|
/*
|
|
* If a zone reaches its high watermark,
|
|
* consider it to be no longer congested. It's
|
|
* possible there are dirty pages backed by
|
|
* congested BDIs but as pressure is relieved,
|
|
* spectulatively avoid congestion waits
|
|
*/
|
|
zone_clear_flag(zone, ZONE_CONGESTED);
|
|
}
|
|
|
|
}
|
|
if (all_zones_ok)
|
|
break; /* kswapd: all done */
|
|
/*
|
|
* OK, kswapd is getting into trouble. Take a nap, then take
|
|
* another pass across the zones.
|
|
*/
|
|
if (total_scanned && (priority < DEF_PRIORITY - 2)) {
|
|
if (has_under_min_watermark_zone)
|
|
count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT);
|
|
else
|
|
congestion_wait(BLK_RW_ASYNC, HZ/10);
|
|
}
|
|
|
|
/*
|
|
* We do this so kswapd doesn't build up large priorities for
|
|
* example when it is freeing in parallel with allocators. It
|
|
* matches the direct reclaim path behaviour in terms of impact
|
|
* on zone->*_priority.
|
|
*/
|
|
if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX)
|
|
break;
|
|
}
|
|
out:
|
|
if (!all_zones_ok) {
|
|
cond_resched();
|
|
|
|
try_to_freeze();
|
|
|
|
/*
|
|
* Fragmentation may mean that the system cannot be
|
|
* rebalanced for high-order allocations in all zones.
|
|
* At this point, if nr_reclaimed < SWAP_CLUSTER_MAX,
|
|
* it means the zones have been fully scanned and are still
|
|
* not balanced. For high-order allocations, there is
|
|
* little point trying all over again as kswapd may
|
|
* infinite loop.
|
|
*
|
|
* Instead, recheck all watermarks at order-0 as they
|
|
* are the most important. If watermarks are ok, kswapd will go
|
|
* back to sleep. High-order users can still perform direct
|
|
* reclaim if they wish.
|
|
*/
|
|
if (sc.nr_reclaimed < SWAP_CLUSTER_MAX)
|
|
order = sc.order = 0;
|
|
|
|
goto loop_again;
|
|
}
|
|
|
|
return sc.nr_reclaimed;
|
|
}
|
|
|
|
/*
|
|
* The background pageout daemon, started as a kernel thread
|
|
* from the init process.
|
|
*
|
|
* This basically trickles out pages so that we have _some_
|
|
* free memory available even if there is no other activity
|
|
* that frees anything up. This is needed for things like routing
|
|
* etc, where we otherwise might have all activity going on in
|
|
* asynchronous contexts that cannot page things out.
|
|
*
|
|
* If there are applications that are active memory-allocators
|
|
* (most normal use), this basically shouldn't matter.
|
|
*/
|
|
static int kswapd(void *p)
|
|
{
|
|
unsigned long order;
|
|
pg_data_t *pgdat = (pg_data_t*)p;
|
|
struct task_struct *tsk = current;
|
|
DEFINE_WAIT(wait);
|
|
struct reclaim_state reclaim_state = {
|
|
.reclaimed_slab = 0,
|
|
};
|
|
const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
|
|
|
|
lockdep_set_current_reclaim_state(GFP_KERNEL);
|
|
|
|
if (!cpumask_empty(cpumask))
|
|
set_cpus_allowed_ptr(tsk, cpumask);
|
|
current->reclaim_state = &reclaim_state;
|
|
|
|
/*
|
|
* Tell the memory management that we're a "memory allocator",
|
|
* and that if we need more memory we should get access to it
|
|
* regardless (see "__alloc_pages()"). "kswapd" should
|
|
* never get caught in the normal page freeing logic.
|
|
*
|
|
* (Kswapd normally doesn't need memory anyway, but sometimes
|
|
* you need a small amount of memory in order to be able to
|
|
* page out something else, and this flag essentially protects
|
|
* us from recursively trying to free more memory as we're
|
|
* trying to free the first piece of memory in the first place).
|
|
*/
|
|
tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
|
|
set_freezable();
|
|
|
|
order = 0;
|
|
for ( ; ; ) {
|
|
unsigned long new_order;
|
|
int ret;
|
|
|
|
prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
|
|
new_order = pgdat->kswapd_max_order;
|
|
pgdat->kswapd_max_order = 0;
|
|
if (order < new_order) {
|
|
/*
|
|
* Don't sleep if someone wants a larger 'order'
|
|
* allocation
|
|
*/
|
|
order = new_order;
|
|
} else {
|
|
if (!freezing(current) && !kthread_should_stop()) {
|
|
long remaining = 0;
|
|
|
|
/* Try to sleep for a short interval */
|
|
if (!sleeping_prematurely(pgdat, order, remaining)) {
|
|
remaining = schedule_timeout(HZ/10);
|
|
finish_wait(&pgdat->kswapd_wait, &wait);
|
|
prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
|
|
}
|
|
|
|
/*
|
|
* After a short sleep, check if it was a
|
|
* premature sleep. If not, then go fully
|
|
* to sleep until explicitly woken up
|
|
*/
|
|
if (!sleeping_prematurely(pgdat, order, remaining)) {
|
|
trace_mm_vmscan_kswapd_sleep(pgdat->node_id);
|
|
schedule();
|
|
} else {
|
|
if (remaining)
|
|
count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY);
|
|
else
|
|
count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY);
|
|
}
|
|
}
|
|
|
|
order = pgdat->kswapd_max_order;
|
|
}
|
|
finish_wait(&pgdat->kswapd_wait, &wait);
|
|
|
|
ret = try_to_freeze();
|
|
if (kthread_should_stop())
|
|
break;
|
|
|
|
/*
|
|
* We can speed up thawing tasks if we don't call balance_pgdat
|
|
* after returning from the refrigerator
|
|
*/
|
|
if (!ret) {
|
|
trace_mm_vmscan_kswapd_wake(pgdat->node_id, order);
|
|
balance_pgdat(pgdat, order);
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* A zone is low on free memory, so wake its kswapd task to service it.
|
|
*/
|
|
void wakeup_kswapd(struct zone *zone, int order)
|
|
{
|
|
pg_data_t *pgdat;
|
|
|
|
if (!populated_zone(zone))
|
|
return;
|
|
|
|
pgdat = zone->zone_pgdat;
|
|
if (zone_watermark_ok(zone, order, low_wmark_pages(zone), 0, 0))
|
|
return;
|
|
if (pgdat->kswapd_max_order < order)
|
|
pgdat->kswapd_max_order = order;
|
|
trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order);
|
|
if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
|
|
return;
|
|
if (!waitqueue_active(&pgdat->kswapd_wait))
|
|
return;
|
|
wake_up_interruptible(&pgdat->kswapd_wait);
|
|
}
|
|
|
|
/*
|
|
* The reclaimable count would be mostly accurate.
|
|
* The less reclaimable pages may be
|
|
* - mlocked pages, which will be moved to unevictable list when encountered
|
|
* - mapped pages, which may require several travels to be reclaimed
|
|
* - dirty pages, which is not "instantly" reclaimable
|
|
*/
|
|
unsigned long global_reclaimable_pages(void)
|
|
{
|
|
int nr;
|
|
|
|
nr = global_page_state(NR_ACTIVE_FILE) +
|
|
global_page_state(NR_INACTIVE_FILE);
|
|
|
|
if (nr_swap_pages > 0)
|
|
nr += global_page_state(NR_ACTIVE_ANON) +
|
|
global_page_state(NR_INACTIVE_ANON);
|
|
|
|
return nr;
|
|
}
|
|
|
|
unsigned long zone_reclaimable_pages(struct zone *zone)
|
|
{
|
|
int nr;
|
|
|
|
nr = zone_page_state(zone, NR_ACTIVE_FILE) +
|
|
zone_page_state(zone, NR_INACTIVE_FILE);
|
|
|
|
if (nr_swap_pages > 0)
|
|
nr += zone_page_state(zone, NR_ACTIVE_ANON) +
|
|
zone_page_state(zone, NR_INACTIVE_ANON);
|
|
|
|
return nr;
|
|
}
|
|
|
|
#ifdef CONFIG_HIBERNATION
|
|
/*
|
|
* Try to free `nr_to_reclaim' of memory, system-wide, and return the number of
|
|
* freed pages.
|
|
*
|
|
* Rather than trying to age LRUs the aim is to preserve the overall
|
|
* LRU order by reclaiming preferentially
|
|
* inactive > active > active referenced > active mapped
|
|
*/
|
|
unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
|
|
{
|
|
struct reclaim_state reclaim_state;
|
|
struct scan_control sc = {
|
|
.gfp_mask = GFP_HIGHUSER_MOVABLE,
|
|
.may_swap = 1,
|
|
.may_unmap = 1,
|
|
.may_writepage = 1,
|
|
.nr_to_reclaim = nr_to_reclaim,
|
|
.hibernation_mode = 1,
|
|
.swappiness = vm_swappiness,
|
|
.order = 0,
|
|
};
|
|
struct zonelist * zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
|
|
struct task_struct *p = current;
|
|
unsigned long nr_reclaimed;
|
|
|
|
p->flags |= PF_MEMALLOC;
|
|
lockdep_set_current_reclaim_state(sc.gfp_mask);
|
|
reclaim_state.reclaimed_slab = 0;
|
|
p->reclaim_state = &reclaim_state;
|
|
|
|
nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
|
|
|
|
p->reclaim_state = NULL;
|
|
lockdep_clear_current_reclaim_state();
|
|
p->flags &= ~PF_MEMALLOC;
|
|
|
|
return nr_reclaimed;
|
|
}
|
|
#endif /* CONFIG_HIBERNATION */
|
|
|
|
/* It's optimal to keep kswapds on the same CPUs as their memory, but
|
|
not required for correctness. So if the last cpu in a node goes
|
|
away, we get changed to run anywhere: as the first one comes back,
|
|
restore their cpu bindings. */
|
|
static int __devinit cpu_callback(struct notifier_block *nfb,
|
|
unsigned long action, void *hcpu)
|
|
{
|
|
int nid;
|
|
|
|
if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) {
|
|
for_each_node_state(nid, N_HIGH_MEMORY) {
|
|
pg_data_t *pgdat = NODE_DATA(nid);
|
|
const struct cpumask *mask;
|
|
|
|
mask = cpumask_of_node(pgdat->node_id);
|
|
|
|
if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids)
|
|
/* One of our CPUs online: restore mask */
|
|
set_cpus_allowed_ptr(pgdat->kswapd, mask);
|
|
}
|
|
}
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
/*
|
|
* This kswapd start function will be called by init and node-hot-add.
|
|
* On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added.
|
|
*/
|
|
int kswapd_run(int nid)
|
|
{
|
|
pg_data_t *pgdat = NODE_DATA(nid);
|
|
int ret = 0;
|
|
|
|
if (pgdat->kswapd)
|
|
return 0;
|
|
|
|
pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid);
|
|
if (IS_ERR(pgdat->kswapd)) {
|
|
/* failure at boot is fatal */
|
|
BUG_ON(system_state == SYSTEM_BOOTING);
|
|
printk("Failed to start kswapd on node %d\n",nid);
|
|
ret = -1;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Called by memory hotplug when all memory in a node is offlined.
|
|
*/
|
|
void kswapd_stop(int nid)
|
|
{
|
|
struct task_struct *kswapd = NODE_DATA(nid)->kswapd;
|
|
|
|
if (kswapd)
|
|
kthread_stop(kswapd);
|
|
}
|
|
|
|
static int __init kswapd_init(void)
|
|
{
|
|
int nid;
|
|
|
|
swap_setup();
|
|
for_each_node_state(nid, N_HIGH_MEMORY)
|
|
kswapd_run(nid);
|
|
hotcpu_notifier(cpu_callback, 0);
|
|
return 0;
|
|
}
|
|
|
|
module_init(kswapd_init)
|
|
|
|
#ifdef CONFIG_NUMA
|
|
/*
|
|
* Zone reclaim mode
|
|
*
|
|
* If non-zero call zone_reclaim when the number of free pages falls below
|
|
* the watermarks.
|
|
*/
|
|
int zone_reclaim_mode __read_mostly;
|
|
|
|
#define RECLAIM_OFF 0
|
|
#define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */
|
|
#define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */
|
|
#define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */
|
|
|
|
/*
|
|
* Priority for ZONE_RECLAIM. This determines the fraction of pages
|
|
* of a node considered for each zone_reclaim. 4 scans 1/16th of
|
|
* a zone.
|
|
*/
|
|
#define ZONE_RECLAIM_PRIORITY 4
|
|
|
|
/*
|
|
* Percentage of pages in a zone that must be unmapped for zone_reclaim to
|
|
* occur.
|
|
*/
|
|
int sysctl_min_unmapped_ratio = 1;
|
|
|
|
/*
|
|
* If the number of slab pages in a zone grows beyond this percentage then
|
|
* slab reclaim needs to occur.
|
|
*/
|
|
int sysctl_min_slab_ratio = 5;
|
|
|
|
static inline unsigned long zone_unmapped_file_pages(struct zone *zone)
|
|
{
|
|
unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED);
|
|
unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) +
|
|
zone_page_state(zone, NR_ACTIVE_FILE);
|
|
|
|
/*
|
|
* It's possible for there to be more file mapped pages than
|
|
* accounted for by the pages on the file LRU lists because
|
|
* tmpfs pages accounted for as ANON can also be FILE_MAPPED
|
|
*/
|
|
return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0;
|
|
}
|
|
|
|
/* Work out how many page cache pages we can reclaim in this reclaim_mode */
|
|
static long zone_pagecache_reclaimable(struct zone *zone)
|
|
{
|
|
long nr_pagecache_reclaimable;
|
|
long delta = 0;
|
|
|
|
/*
|
|
* If RECLAIM_SWAP is set, then all file pages are considered
|
|
* potentially reclaimable. Otherwise, we have to worry about
|
|
* pages like swapcache and zone_unmapped_file_pages() provides
|
|
* a better estimate
|
|
*/
|
|
if (zone_reclaim_mode & RECLAIM_SWAP)
|
|
nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES);
|
|
else
|
|
nr_pagecache_reclaimable = zone_unmapped_file_pages(zone);
|
|
|
|
/* If we can't clean pages, remove dirty pages from consideration */
|
|
if (!(zone_reclaim_mode & RECLAIM_WRITE))
|
|
delta += zone_page_state(zone, NR_FILE_DIRTY);
|
|
|
|
/* Watch for any possible underflows due to delta */
|
|
if (unlikely(delta > nr_pagecache_reclaimable))
|
|
delta = nr_pagecache_reclaimable;
|
|
|
|
return nr_pagecache_reclaimable - delta;
|
|
}
|
|
|
|
/*
|
|
* Try to free up some pages from this zone through reclaim.
|
|
*/
|
|
static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
|
|
{
|
|
/* Minimum pages needed in order to stay on node */
|
|
const unsigned long nr_pages = 1 << order;
|
|
struct task_struct *p = current;
|
|
struct reclaim_state reclaim_state;
|
|
int priority;
|
|
struct scan_control sc = {
|
|
.may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
|
|
.may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP),
|
|
.may_swap = 1,
|
|
.nr_to_reclaim = max_t(unsigned long, nr_pages,
|
|
SWAP_CLUSTER_MAX),
|
|
.gfp_mask = gfp_mask,
|
|
.swappiness = vm_swappiness,
|
|
.order = order,
|
|
};
|
|
unsigned long nr_slab_pages0, nr_slab_pages1;
|
|
|
|
cond_resched();
|
|
/*
|
|
* We need to be able to allocate from the reserves for RECLAIM_SWAP
|
|
* and we also need to be able to write out pages for RECLAIM_WRITE
|
|
* and RECLAIM_SWAP.
|
|
*/
|
|
p->flags |= PF_MEMALLOC | PF_SWAPWRITE;
|
|
lockdep_set_current_reclaim_state(gfp_mask);
|
|
reclaim_state.reclaimed_slab = 0;
|
|
p->reclaim_state = &reclaim_state;
|
|
|
|
if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) {
|
|
/*
|
|
* Free memory by calling shrink zone with increasing
|
|
* priorities until we have enough memory freed.
|
|
*/
|
|
priority = ZONE_RECLAIM_PRIORITY;
|
|
do {
|
|
shrink_zone(priority, zone, &sc);
|
|
priority--;
|
|
} while (priority >= 0 && sc.nr_reclaimed < nr_pages);
|
|
}
|
|
|
|
nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
|
|
if (nr_slab_pages0 > zone->min_slab_pages) {
|
|
/*
|
|
* shrink_slab() does not currently allow us to determine how
|
|
* many pages were freed in this zone. So we take the current
|
|
* number of slab pages and shake the slab until it is reduced
|
|
* by the same nr_pages that we used for reclaiming unmapped
|
|
* pages.
|
|
*
|
|
* Note that shrink_slab will free memory on all zones and may
|
|
* take a long time.
|
|
*/
|
|
for (;;) {
|
|
unsigned long lru_pages = zone_reclaimable_pages(zone);
|
|
|
|
/* No reclaimable slab or very low memory pressure */
|
|
if (!shrink_slab(sc.nr_scanned, gfp_mask, lru_pages))
|
|
break;
|
|
|
|
/* Freed enough memory */
|
|
nr_slab_pages1 = zone_page_state(zone,
|
|
NR_SLAB_RECLAIMABLE);
|
|
if (nr_slab_pages1 + nr_pages <= nr_slab_pages0)
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Update nr_reclaimed by the number of slab pages we
|
|
* reclaimed from this zone.
|
|
*/
|
|
nr_slab_pages1 = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
|
|
if (nr_slab_pages1 < nr_slab_pages0)
|
|
sc.nr_reclaimed += nr_slab_pages0 - nr_slab_pages1;
|
|
}
|
|
|
|
p->reclaim_state = NULL;
|
|
current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE);
|
|
lockdep_clear_current_reclaim_state();
|
|
return sc.nr_reclaimed >= nr_pages;
|
|
}
|
|
|
|
int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
|
|
{
|
|
int node_id;
|
|
int ret;
|
|
|
|
/*
|
|
* Zone reclaim reclaims unmapped file backed pages and
|
|
* slab pages if we are over the defined limits.
|
|
*
|
|
* A small portion of unmapped file backed pages is needed for
|
|
* file I/O otherwise pages read by file I/O will be immediately
|
|
* thrown out if the zone is overallocated. So we do not reclaim
|
|
* if less than a specified percentage of the zone is used by
|
|
* unmapped file backed pages.
|
|
*/
|
|
if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages &&
|
|
zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages)
|
|
return ZONE_RECLAIM_FULL;
|
|
|
|
if (zone->all_unreclaimable)
|
|
return ZONE_RECLAIM_FULL;
|
|
|
|
/*
|
|
* Do not scan if the allocation should not be delayed.
|
|
*/
|
|
if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC))
|
|
return ZONE_RECLAIM_NOSCAN;
|
|
|
|
/*
|
|
* Only run zone reclaim on the local zone or on zones that do not
|
|
* have associated processors. This will favor the local processor
|
|
* over remote processors and spread off node memory allocations
|
|
* as wide as possible.
|
|
*/
|
|
node_id = zone_to_nid(zone);
|
|
if (node_state(node_id, N_CPU) && node_id != numa_node_id())
|
|
return ZONE_RECLAIM_NOSCAN;
|
|
|
|
if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED))
|
|
return ZONE_RECLAIM_NOSCAN;
|
|
|
|
ret = __zone_reclaim(zone, gfp_mask, order);
|
|
zone_clear_flag(zone, ZONE_RECLAIM_LOCKED);
|
|
|
|
if (!ret)
|
|
count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED);
|
|
|
|
return ret;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* page_evictable - test whether a page is evictable
|
|
* @page: the page to test
|
|
* @vma: the VMA in which the page is or will be mapped, may be NULL
|
|
*
|
|
* Test whether page is evictable--i.e., should be placed on active/inactive
|
|
* lists vs unevictable list. The vma argument is !NULL when called from the
|
|
* fault path to determine how to instantate a new page.
|
|
*
|
|
* Reasons page might not be evictable:
|
|
* (1) page's mapping marked unevictable
|
|
* (2) page is part of an mlocked VMA
|
|
*
|
|
*/
|
|
int page_evictable(struct page *page, struct vm_area_struct *vma)
|
|
{
|
|
|
|
if (mapping_unevictable(page_mapping(page)))
|
|
return 0;
|
|
|
|
if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page)))
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
/**
|
|
* check_move_unevictable_page - check page for evictability and move to appropriate zone lru list
|
|
* @page: page to check evictability and move to appropriate lru list
|
|
* @zone: zone page is in
|
|
*
|
|
* Checks a page for evictability and moves the page to the appropriate
|
|
* zone lru list.
|
|
*
|
|
* Restrictions: zone->lru_lock must be held, page must be on LRU and must
|
|
* have PageUnevictable set.
|
|
*/
|
|
static void check_move_unevictable_page(struct page *page, struct zone *zone)
|
|
{
|
|
VM_BUG_ON(PageActive(page));
|
|
|
|
retry:
|
|
ClearPageUnevictable(page);
|
|
if (page_evictable(page, NULL)) {
|
|
enum lru_list l = page_lru_base_type(page);
|
|
|
|
__dec_zone_state(zone, NR_UNEVICTABLE);
|
|
list_move(&page->lru, &zone->lru[l].list);
|
|
mem_cgroup_move_lists(page, LRU_UNEVICTABLE, l);
|
|
__inc_zone_state(zone, NR_INACTIVE_ANON + l);
|
|
__count_vm_event(UNEVICTABLE_PGRESCUED);
|
|
} else {
|
|
/*
|
|
* rotate unevictable list
|
|
*/
|
|
SetPageUnevictable(page);
|
|
list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list);
|
|
mem_cgroup_rotate_lru_list(page, LRU_UNEVICTABLE);
|
|
if (page_evictable(page, NULL))
|
|
goto retry;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* scan_mapping_unevictable_pages - scan an address space for evictable pages
|
|
* @mapping: struct address_space to scan for evictable pages
|
|
*
|
|
* Scan all pages in mapping. Check unevictable pages for
|
|
* evictability and move them to the appropriate zone lru list.
|
|
*/
|
|
void scan_mapping_unevictable_pages(struct address_space *mapping)
|
|
{
|
|
pgoff_t next = 0;
|
|
pgoff_t end = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >>
|
|
PAGE_CACHE_SHIFT;
|
|
struct zone *zone;
|
|
struct pagevec pvec;
|
|
|
|
if (mapping->nrpages == 0)
|
|
return;
|
|
|
|
pagevec_init(&pvec, 0);
|
|
while (next < end &&
|
|
pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
|
|
int i;
|
|
int pg_scanned = 0;
|
|
|
|
zone = NULL;
|
|
|
|
for (i = 0; i < pagevec_count(&pvec); i++) {
|
|
struct page *page = pvec.pages[i];
|
|
pgoff_t page_index = page->index;
|
|
struct zone *pagezone = page_zone(page);
|
|
|
|
pg_scanned++;
|
|
if (page_index > next)
|
|
next = page_index;
|
|
next++;
|
|
|
|
if (pagezone != zone) {
|
|
if (zone)
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
zone = pagezone;
|
|
spin_lock_irq(&zone->lru_lock);
|
|
}
|
|
|
|
if (PageLRU(page) && PageUnevictable(page))
|
|
check_move_unevictable_page(page, zone);
|
|
}
|
|
if (zone)
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
pagevec_release(&pvec);
|
|
|
|
count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned);
|
|
}
|
|
|
|
}
|
|
|
|
/**
|
|
* scan_zone_unevictable_pages - check unevictable list for evictable pages
|
|
* @zone - zone of which to scan the unevictable list
|
|
*
|
|
* Scan @zone's unevictable LRU lists to check for pages that have become
|
|
* evictable. Move those that have to @zone's inactive list where they
|
|
* become candidates for reclaim, unless shrink_inactive_zone() decides
|
|
* to reactivate them. Pages that are still unevictable are rotated
|
|
* back onto @zone's unevictable list.
|
|
*/
|
|
#define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */
|
|
static void scan_zone_unevictable_pages(struct zone *zone)
|
|
{
|
|
struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list;
|
|
unsigned long scan;
|
|
unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE);
|
|
|
|
while (nr_to_scan > 0) {
|
|
unsigned long batch_size = min(nr_to_scan,
|
|
SCAN_UNEVICTABLE_BATCH_SIZE);
|
|
|
|
spin_lock_irq(&zone->lru_lock);
|
|
for (scan = 0; scan < batch_size; scan++) {
|
|
struct page *page = lru_to_page(l_unevictable);
|
|
|
|
if (!trylock_page(page))
|
|
continue;
|
|
|
|
prefetchw_prev_lru_page(page, l_unevictable, flags);
|
|
|
|
if (likely(PageLRU(page) && PageUnevictable(page)))
|
|
check_move_unevictable_page(page, zone);
|
|
|
|
unlock_page(page);
|
|
}
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
|
|
nr_to_scan -= batch_size;
|
|
}
|
|
}
|
|
|
|
|
|
/**
|
|
* scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages
|
|
*
|
|
* A really big hammer: scan all zones' unevictable LRU lists to check for
|
|
* pages that have become evictable. Move those back to the zones'
|
|
* inactive list where they become candidates for reclaim.
|
|
* This occurs when, e.g., we have unswappable pages on the unevictable lists,
|
|
* and we add swap to the system. As such, it runs in the context of a task
|
|
* that has possibly/probably made some previously unevictable pages
|
|
* evictable.
|
|
*/
|
|
static void scan_all_zones_unevictable_pages(void)
|
|
{
|
|
struct zone *zone;
|
|
|
|
for_each_zone(zone) {
|
|
scan_zone_unevictable_pages(zone);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* scan_unevictable_pages [vm] sysctl handler. On demand re-scan of
|
|
* all nodes' unevictable lists for evictable pages
|
|
*/
|
|
unsigned long scan_unevictable_pages;
|
|
|
|
int scan_unevictable_handler(struct ctl_table *table, int write,
|
|
void __user *buffer,
|
|
size_t *length, loff_t *ppos)
|
|
{
|
|
proc_doulongvec_minmax(table, write, buffer, length, ppos);
|
|
|
|
if (write && *(unsigned long *)table->data)
|
|
scan_all_zones_unevictable_pages();
|
|
|
|
scan_unevictable_pages = 0;
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_NUMA
|
|
/*
|
|
* per node 'scan_unevictable_pages' attribute. On demand re-scan of
|
|
* a specified node's per zone unevictable lists for evictable pages.
|
|
*/
|
|
|
|
static ssize_t read_scan_unevictable_node(struct sys_device *dev,
|
|
struct sysdev_attribute *attr,
|
|
char *buf)
|
|
{
|
|
return sprintf(buf, "0\n"); /* always zero; should fit... */
|
|
}
|
|
|
|
static ssize_t write_scan_unevictable_node(struct sys_device *dev,
|
|
struct sysdev_attribute *attr,
|
|
const char *buf, size_t count)
|
|
{
|
|
struct zone *node_zones = NODE_DATA(dev->id)->node_zones;
|
|
struct zone *zone;
|
|
unsigned long res;
|
|
unsigned long req = strict_strtoul(buf, 10, &res);
|
|
|
|
if (!req)
|
|
return 1; /* zero is no-op */
|
|
|
|
for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
|
|
if (!populated_zone(zone))
|
|
continue;
|
|
scan_zone_unevictable_pages(zone);
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
|
|
static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR,
|
|
read_scan_unevictable_node,
|
|
write_scan_unevictable_node);
|
|
|
|
int scan_unevictable_register_node(struct node *node)
|
|
{
|
|
return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages);
|
|
}
|
|
|
|
void scan_unevictable_unregister_node(struct node *node)
|
|
{
|
|
sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages);
|
|
}
|
|
#endif
|