mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-26 19:00:25 +00:00
![Linus Torvalds](/assets/img/avatar_default.png)
* 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block: (65 commits) Documentation/iostats.txt: bit-size reference etc. cfq-iosched: removing unnecessary think time checking cfq-iosched: Don't clear queue stats when preempt. blk-throttle: Reset group slice when limits are changed blk-cgroup: Only give unaccounted_time under debug cfq-iosched: Don't set active queue in preempt block: fix non-atomic access to genhd inflight structures block: attempt to merge with existing requests on plug flush block: NULL dereference on error path in __blkdev_get() cfq-iosched: Don't update group weights when on service tree fs: assign sb->s_bdi to default_backing_dev_info if the bdi is going away block: Require subsystems to explicitly allocate bio_set integrity mempool jbd2: finish conversion from WRITE_SYNC_PLUG to WRITE_SYNC and explicit plugging jbd: finish conversion from WRITE_SYNC_PLUG to WRITE_SYNC and explicit plugging fs: make fsync_buffers_list() plug mm: make generic_writepages() use plugging blk-cgroup: Add unaccounted time to timeslice_used. block: fixup plugging stubs for !CONFIG_BLOCK block: remove obsolete comments for blkdev_issue_zeroout. blktrace: Use rq->cmd_flags directly in blk_add_trace_rq. ... Fix up conflicts in fs/{aio.c,super.c}
3335 lines
92 KiB
C
3335 lines
92 KiB
C
/*
|
|
* linux/mm/vmscan.c
|
|
*
|
|
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
|
|
*
|
|
* Swap reorganised 29.12.95, Stephen Tweedie.
|
|
* kswapd added: 7.1.96 sct
|
|
* Removed kswapd_ctl limits, and swap out as many pages as needed
|
|
* to bring the system back to freepages.high: 2.4.97, Rik van Riel.
|
|
* Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com).
|
|
* Multiqueue VM started 5.8.00, Rik van Riel.
|
|
*/
|
|
|
|
#include <linux/mm.h>
|
|
#include <linux/module.h>
|
|
#include <linux/gfp.h>
|
|
#include <linux/kernel_stat.h>
|
|
#include <linux/swap.h>
|
|
#include <linux/pagemap.h>
|
|
#include <linux/init.h>
|
|
#include <linux/highmem.h>
|
|
#include <linux/vmstat.h>
|
|
#include <linux/file.h>
|
|
#include <linux/writeback.h>
|
|
#include <linux/blkdev.h>
|
|
#include <linux/buffer_head.h> /* for try_to_release_page(),
|
|
buffer_heads_over_limit */
|
|
#include <linux/mm_inline.h>
|
|
#include <linux/pagevec.h>
|
|
#include <linux/backing-dev.h>
|
|
#include <linux/rmap.h>
|
|
#include <linux/topology.h>
|
|
#include <linux/cpu.h>
|
|
#include <linux/cpuset.h>
|
|
#include <linux/compaction.h>
|
|
#include <linux/notifier.h>
|
|
#include <linux/rwsem.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/kthread.h>
|
|
#include <linux/freezer.h>
|
|
#include <linux/memcontrol.h>
|
|
#include <linux/delayacct.h>
|
|
#include <linux/sysctl.h>
|
|
|
|
#include <asm/tlbflush.h>
|
|
#include <asm/div64.h>
|
|
|
|
#include <linux/swapops.h>
|
|
|
|
#include "internal.h"
|
|
|
|
#define CREATE_TRACE_POINTS
|
|
#include <trace/events/vmscan.h>
|
|
|
|
/*
|
|
* reclaim_mode determines how the inactive list is shrunk
|
|
* RECLAIM_MODE_SINGLE: Reclaim only order-0 pages
|
|
* RECLAIM_MODE_ASYNC: Do not block
|
|
* RECLAIM_MODE_SYNC: Allow blocking e.g. call wait_on_page_writeback
|
|
* RECLAIM_MODE_LUMPYRECLAIM: For high-order allocations, take a reference
|
|
* page from the LRU and reclaim all pages within a
|
|
* naturally aligned range
|
|
* RECLAIM_MODE_COMPACTION: For high-order allocations, reclaim a number of
|
|
* order-0 pages and then compact the zone
|
|
*/
|
|
typedef unsigned __bitwise__ reclaim_mode_t;
|
|
#define RECLAIM_MODE_SINGLE ((__force reclaim_mode_t)0x01u)
|
|
#define RECLAIM_MODE_ASYNC ((__force reclaim_mode_t)0x02u)
|
|
#define RECLAIM_MODE_SYNC ((__force reclaim_mode_t)0x04u)
|
|
#define RECLAIM_MODE_LUMPYRECLAIM ((__force reclaim_mode_t)0x08u)
|
|
#define RECLAIM_MODE_COMPACTION ((__force reclaim_mode_t)0x10u)
|
|
|
|
struct scan_control {
|
|
/* Incremented by the number of inactive pages that were scanned */
|
|
unsigned long nr_scanned;
|
|
|
|
/* Number of pages freed so far during a call to shrink_zones() */
|
|
unsigned long nr_reclaimed;
|
|
|
|
/* How many pages shrink_list() should reclaim */
|
|
unsigned long nr_to_reclaim;
|
|
|
|
unsigned long hibernation_mode;
|
|
|
|
/* This context's GFP mask */
|
|
gfp_t gfp_mask;
|
|
|
|
int may_writepage;
|
|
|
|
/* Can mapped pages be reclaimed? */
|
|
int may_unmap;
|
|
|
|
/* Can pages be swapped as part of reclaim? */
|
|
int may_swap;
|
|
|
|
int swappiness;
|
|
|
|
int order;
|
|
|
|
/*
|
|
* Intend to reclaim enough continuous memory rather than reclaim
|
|
* enough amount of memory. i.e, mode for high order allocation.
|
|
*/
|
|
reclaim_mode_t reclaim_mode;
|
|
|
|
/* Which cgroup do we reclaim from */
|
|
struct mem_cgroup *mem_cgroup;
|
|
|
|
/*
|
|
* Nodemask of nodes allowed by the caller. If NULL, all nodes
|
|
* are scanned.
|
|
*/
|
|
nodemask_t *nodemask;
|
|
};
|
|
|
|
#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
|
|
|
|
#ifdef ARCH_HAS_PREFETCH
|
|
#define prefetch_prev_lru_page(_page, _base, _field) \
|
|
do { \
|
|
if ((_page)->lru.prev != _base) { \
|
|
struct page *prev; \
|
|
\
|
|
prev = lru_to_page(&(_page->lru)); \
|
|
prefetch(&prev->_field); \
|
|
} \
|
|
} while (0)
|
|
#else
|
|
#define prefetch_prev_lru_page(_page, _base, _field) do { } while (0)
|
|
#endif
|
|
|
|
#ifdef ARCH_HAS_PREFETCHW
|
|
#define prefetchw_prev_lru_page(_page, _base, _field) \
|
|
do { \
|
|
if ((_page)->lru.prev != _base) { \
|
|
struct page *prev; \
|
|
\
|
|
prev = lru_to_page(&(_page->lru)); \
|
|
prefetchw(&prev->_field); \
|
|
} \
|
|
} while (0)
|
|
#else
|
|
#define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0)
|
|
#endif
|
|
|
|
/*
|
|
* From 0 .. 100. Higher means more swappy.
|
|
*/
|
|
int vm_swappiness = 60;
|
|
long vm_total_pages; /* The total number of pages which the VM controls */
|
|
|
|
static LIST_HEAD(shrinker_list);
|
|
static DECLARE_RWSEM(shrinker_rwsem);
|
|
|
|
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
|
|
#define scanning_global_lru(sc) (!(sc)->mem_cgroup)
|
|
#else
|
|
#define scanning_global_lru(sc) (1)
|
|
#endif
|
|
|
|
static struct zone_reclaim_stat *get_reclaim_stat(struct zone *zone,
|
|
struct scan_control *sc)
|
|
{
|
|
if (!scanning_global_lru(sc))
|
|
return mem_cgroup_get_reclaim_stat(sc->mem_cgroup, zone);
|
|
|
|
return &zone->reclaim_stat;
|
|
}
|
|
|
|
static unsigned long zone_nr_lru_pages(struct zone *zone,
|
|
struct scan_control *sc, enum lru_list lru)
|
|
{
|
|
if (!scanning_global_lru(sc))
|
|
return mem_cgroup_zone_nr_pages(sc->mem_cgroup, zone, lru);
|
|
|
|
return zone_page_state(zone, NR_LRU_BASE + lru);
|
|
}
|
|
|
|
|
|
/*
|
|
* Add a shrinker callback to be called from the vm
|
|
*/
|
|
void register_shrinker(struct shrinker *shrinker)
|
|
{
|
|
shrinker->nr = 0;
|
|
down_write(&shrinker_rwsem);
|
|
list_add_tail(&shrinker->list, &shrinker_list);
|
|
up_write(&shrinker_rwsem);
|
|
}
|
|
EXPORT_SYMBOL(register_shrinker);
|
|
|
|
/*
|
|
* Remove one
|
|
*/
|
|
void unregister_shrinker(struct shrinker *shrinker)
|
|
{
|
|
down_write(&shrinker_rwsem);
|
|
list_del(&shrinker->list);
|
|
up_write(&shrinker_rwsem);
|
|
}
|
|
EXPORT_SYMBOL(unregister_shrinker);
|
|
|
|
#define SHRINK_BATCH 128
|
|
/*
|
|
* Call the shrink functions to age shrinkable caches
|
|
*
|
|
* Here we assume it costs one seek to replace a lru page and that it also
|
|
* takes a seek to recreate a cache object. With this in mind we age equal
|
|
* percentages of the lru and ageable caches. This should balance the seeks
|
|
* generated by these structures.
|
|
*
|
|
* If the vm encountered mapped pages on the LRU it increase the pressure on
|
|
* slab to avoid swapping.
|
|
*
|
|
* We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits.
|
|
*
|
|
* `lru_pages' represents the number of on-LRU pages in all the zones which
|
|
* are eligible for the caller's allocation attempt. It is used for balancing
|
|
* slab reclaim versus page reclaim.
|
|
*
|
|
* Returns the number of slab objects which we shrunk.
|
|
*/
|
|
unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
|
|
unsigned long lru_pages)
|
|
{
|
|
struct shrinker *shrinker;
|
|
unsigned long ret = 0;
|
|
|
|
if (scanned == 0)
|
|
scanned = SWAP_CLUSTER_MAX;
|
|
|
|
if (!down_read_trylock(&shrinker_rwsem))
|
|
return 1; /* Assume we'll be able to shrink next time */
|
|
|
|
list_for_each_entry(shrinker, &shrinker_list, list) {
|
|
unsigned long long delta;
|
|
unsigned long total_scan;
|
|
unsigned long max_pass;
|
|
|
|
max_pass = (*shrinker->shrink)(shrinker, 0, gfp_mask);
|
|
delta = (4 * scanned) / shrinker->seeks;
|
|
delta *= max_pass;
|
|
do_div(delta, lru_pages + 1);
|
|
shrinker->nr += delta;
|
|
if (shrinker->nr < 0) {
|
|
printk(KERN_ERR "shrink_slab: %pF negative objects to "
|
|
"delete nr=%ld\n",
|
|
shrinker->shrink, shrinker->nr);
|
|
shrinker->nr = max_pass;
|
|
}
|
|
|
|
/*
|
|
* Avoid risking looping forever due to too large nr value:
|
|
* never try to free more than twice the estimate number of
|
|
* freeable entries.
|
|
*/
|
|
if (shrinker->nr > max_pass * 2)
|
|
shrinker->nr = max_pass * 2;
|
|
|
|
total_scan = shrinker->nr;
|
|
shrinker->nr = 0;
|
|
|
|
while (total_scan >= SHRINK_BATCH) {
|
|
long this_scan = SHRINK_BATCH;
|
|
int shrink_ret;
|
|
int nr_before;
|
|
|
|
nr_before = (*shrinker->shrink)(shrinker, 0, gfp_mask);
|
|
shrink_ret = (*shrinker->shrink)(shrinker, this_scan,
|
|
gfp_mask);
|
|
if (shrink_ret == -1)
|
|
break;
|
|
if (shrink_ret < nr_before)
|
|
ret += nr_before - shrink_ret;
|
|
count_vm_events(SLABS_SCANNED, this_scan);
|
|
total_scan -= this_scan;
|
|
|
|
cond_resched();
|
|
}
|
|
|
|
shrinker->nr += total_scan;
|
|
}
|
|
up_read(&shrinker_rwsem);
|
|
return ret;
|
|
}
|
|
|
|
static void set_reclaim_mode(int priority, struct scan_control *sc,
|
|
bool sync)
|
|
{
|
|
reclaim_mode_t syncmode = sync ? RECLAIM_MODE_SYNC : RECLAIM_MODE_ASYNC;
|
|
|
|
/*
|
|
* Initially assume we are entering either lumpy reclaim or
|
|
* reclaim/compaction.Depending on the order, we will either set the
|
|
* sync mode or just reclaim order-0 pages later.
|
|
*/
|
|
if (COMPACTION_BUILD)
|
|
sc->reclaim_mode = RECLAIM_MODE_COMPACTION;
|
|
else
|
|
sc->reclaim_mode = RECLAIM_MODE_LUMPYRECLAIM;
|
|
|
|
/*
|
|
* Avoid using lumpy reclaim or reclaim/compaction if possible by
|
|
* restricting when its set to either costly allocations or when
|
|
* under memory pressure
|
|
*/
|
|
if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
|
|
sc->reclaim_mode |= syncmode;
|
|
else if (sc->order && priority < DEF_PRIORITY - 2)
|
|
sc->reclaim_mode |= syncmode;
|
|
else
|
|
sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC;
|
|
}
|
|
|
|
static void reset_reclaim_mode(struct scan_control *sc)
|
|
{
|
|
sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC;
|
|
}
|
|
|
|
static inline int is_page_cache_freeable(struct page *page)
|
|
{
|
|
/*
|
|
* A freeable page cache page is referenced only by the caller
|
|
* that isolated the page, the page cache radix tree and
|
|
* optional buffer heads at page->private.
|
|
*/
|
|
return page_count(page) - page_has_private(page) == 2;
|
|
}
|
|
|
|
static int may_write_to_queue(struct backing_dev_info *bdi,
|
|
struct scan_control *sc)
|
|
{
|
|
if (current->flags & PF_SWAPWRITE)
|
|
return 1;
|
|
if (!bdi_write_congested(bdi))
|
|
return 1;
|
|
if (bdi == current->backing_dev_info)
|
|
return 1;
|
|
|
|
/* lumpy reclaim for hugepage often need a lot of write */
|
|
if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* We detected a synchronous write error writing a page out. Probably
|
|
* -ENOSPC. We need to propagate that into the address_space for a subsequent
|
|
* fsync(), msync() or close().
|
|
*
|
|
* The tricky part is that after writepage we cannot touch the mapping: nothing
|
|
* prevents it from being freed up. But we have a ref on the page and once
|
|
* that page is locked, the mapping is pinned.
|
|
*
|
|
* We're allowed to run sleeping lock_page() here because we know the caller has
|
|
* __GFP_FS.
|
|
*/
|
|
static void handle_write_error(struct address_space *mapping,
|
|
struct page *page, int error)
|
|
{
|
|
lock_page(page);
|
|
if (page_mapping(page) == mapping)
|
|
mapping_set_error(mapping, error);
|
|
unlock_page(page);
|
|
}
|
|
|
|
/* possible outcome of pageout() */
|
|
typedef enum {
|
|
/* failed to write page out, page is locked */
|
|
PAGE_KEEP,
|
|
/* move page to the active list, page is locked */
|
|
PAGE_ACTIVATE,
|
|
/* page has been sent to the disk successfully, page is unlocked */
|
|
PAGE_SUCCESS,
|
|
/* page is clean and locked */
|
|
PAGE_CLEAN,
|
|
} pageout_t;
|
|
|
|
/*
|
|
* pageout is called by shrink_page_list() for each dirty page.
|
|
* Calls ->writepage().
|
|
*/
|
|
static pageout_t pageout(struct page *page, struct address_space *mapping,
|
|
struct scan_control *sc)
|
|
{
|
|
/*
|
|
* If the page is dirty, only perform writeback if that write
|
|
* will be non-blocking. To prevent this allocation from being
|
|
* stalled by pagecache activity. But note that there may be
|
|
* stalls if we need to run get_block(). We could test
|
|
* PagePrivate for that.
|
|
*
|
|
* If this process is currently in __generic_file_aio_write() against
|
|
* this page's queue, we can perform writeback even if that
|
|
* will block.
|
|
*
|
|
* If the page is swapcache, write it back even if that would
|
|
* block, for some throttling. This happens by accident, because
|
|
* swap_backing_dev_info is bust: it doesn't reflect the
|
|
* congestion state of the swapdevs. Easy to fix, if needed.
|
|
*/
|
|
if (!is_page_cache_freeable(page))
|
|
return PAGE_KEEP;
|
|
if (!mapping) {
|
|
/*
|
|
* Some data journaling orphaned pages can have
|
|
* page->mapping == NULL while being dirty with clean buffers.
|
|
*/
|
|
if (page_has_private(page)) {
|
|
if (try_to_free_buffers(page)) {
|
|
ClearPageDirty(page);
|
|
printk("%s: orphaned page\n", __func__);
|
|
return PAGE_CLEAN;
|
|
}
|
|
}
|
|
return PAGE_KEEP;
|
|
}
|
|
if (mapping->a_ops->writepage == NULL)
|
|
return PAGE_ACTIVATE;
|
|
if (!may_write_to_queue(mapping->backing_dev_info, sc))
|
|
return PAGE_KEEP;
|
|
|
|
if (clear_page_dirty_for_io(page)) {
|
|
int res;
|
|
struct writeback_control wbc = {
|
|
.sync_mode = WB_SYNC_NONE,
|
|
.nr_to_write = SWAP_CLUSTER_MAX,
|
|
.range_start = 0,
|
|
.range_end = LLONG_MAX,
|
|
.for_reclaim = 1,
|
|
};
|
|
|
|
SetPageReclaim(page);
|
|
res = mapping->a_ops->writepage(page, &wbc);
|
|
if (res < 0)
|
|
handle_write_error(mapping, page, res);
|
|
if (res == AOP_WRITEPAGE_ACTIVATE) {
|
|
ClearPageReclaim(page);
|
|
return PAGE_ACTIVATE;
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
if (PageWriteback(page) &&
|
|
(sc->reclaim_mode & RECLAIM_MODE_SYNC))
|
|
wait_on_page_writeback(page);
|
|
|
|
if (!PageWriteback(page)) {
|
|
/* synchronous write or broken a_ops? */
|
|
ClearPageReclaim(page);
|
|
}
|
|
trace_mm_vmscan_writepage(page,
|
|
trace_reclaim_flags(page, sc->reclaim_mode));
|
|
inc_zone_page_state(page, NR_VMSCAN_WRITE);
|
|
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)
|
|
{
|
|
BUG_ON(!PageLocked(page));
|
|
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:
|
|
*
|
|
* get_user_pages(&page);
|
|
* [user mapping goes away]
|
|
* write_to(page);
|
|
* !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))
|
|
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);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
swapcache_free(swap, page);
|
|
} else {
|
|
void (*freepage)(struct page *);
|
|
|
|
freepage = mapping->a_ops->freepage;
|
|
|
|
__delete_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->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM)
|
|
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->reclaim_mode & RECLAIM_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);
|
|
reset_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:
|
|
reset_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 += hpage_nr_pages(page);
|
|
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 += hpage_nr_pages(page);
|
|
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) {
|
|
int numpages = hpage_nr_pages(page);
|
|
lru = page_lru_base_type(page);
|
|
if (PageActive(page)) {
|
|
lru += LRU_ACTIVE;
|
|
ClearPageActive(page);
|
|
nr_active += numpages;
|
|
}
|
|
if (count)
|
|
count[lru] += numpages;
|
|
}
|
|
|
|
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);
|
|
int numpages = hpage_nr_pages(page);
|
|
reclaim_stat->recent_rotated[file] += numpages;
|
|
}
|
|
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->reclaim_mode & RECLAIM_MODE_SINGLE)
|
|
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_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->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ?
|
|
ISOLATE_BOTH : ISOLATE_INACTIVE,
|
|
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->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ?
|
|
ISOLATE_BOTH : ISOLATE_INACTIVE,
|
|
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_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->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 += hpage_nr_pages(page);
|
|
|
|
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 += hpage_nr_pages(page);
|
|
/*
|
|
* 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]);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Reclaim/compaction depends on a number of pages being freed. To avoid
|
|
* disruption to the system, a small number of order-0 pages continue to be
|
|
* rotated and reclaimed in the normal fashion. However, by the time we get
|
|
* back to the allocator and call try_to_compact_zone(), we ensure that
|
|
* there are enough free pages for it to be likely successful
|
|
*/
|
|
static inline bool should_continue_reclaim(struct zone *zone,
|
|
unsigned long nr_reclaimed,
|
|
unsigned long nr_scanned,
|
|
struct scan_control *sc)
|
|
{
|
|
unsigned long pages_for_compaction;
|
|
unsigned long inactive_lru_pages;
|
|
|
|
/* If not in reclaim/compaction mode, stop */
|
|
if (!(sc->reclaim_mode & RECLAIM_MODE_COMPACTION))
|
|
return false;
|
|
|
|
/* Consider stopping depending on scan and reclaim activity */
|
|
if (sc->gfp_mask & __GFP_REPEAT) {
|
|
/*
|
|
* For __GFP_REPEAT allocations, stop reclaiming if the
|
|
* full LRU list has been scanned and we are still failing
|
|
* to reclaim pages. This full LRU scan is potentially
|
|
* expensive but a __GFP_REPEAT caller really wants to succeed
|
|
*/
|
|
if (!nr_reclaimed && !nr_scanned)
|
|
return false;
|
|
} else {
|
|
/*
|
|
* For non-__GFP_REPEAT allocations which can presumably
|
|
* fail without consequence, stop if we failed to reclaim
|
|
* any pages from the last SWAP_CLUSTER_MAX number of
|
|
* pages that were scanned. This will return to the
|
|
* caller faster at the risk reclaim/compaction and
|
|
* the resulting allocation attempt fails
|
|
*/
|
|
if (!nr_reclaimed)
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* If we have not reclaimed enough pages for compaction and the
|
|
* inactive lists are large enough, continue reclaiming
|
|
*/
|
|
pages_for_compaction = (2UL << sc->order);
|
|
inactive_lru_pages = zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON) +
|
|
zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE);
|
|
if (sc->nr_reclaimed < pages_for_compaction &&
|
|
inactive_lru_pages > pages_for_compaction)
|
|
return true;
|
|
|
|
/* If compaction would go ahead or the allocation would succeed, stop */
|
|
switch (compaction_suitable(zone, sc->order)) {
|
|
case COMPACT_PARTIAL:
|
|
case COMPACT_CONTINUE:
|
|
return false;
|
|
default:
|
|
return true;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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, nr_scanned;
|
|
unsigned long nr_to_reclaim = sc->nr_to_reclaim;
|
|
|
|
restart:
|
|
nr_reclaimed = 0;
|
|
nr_scanned = sc->nr_scanned;
|
|
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);
|
|
|
|
/* reclaim/compaction might need reclaim to continue */
|
|
if (should_continue_reclaim(zone, nr_reclaimed,
|
|
sc->nr_scanned - nr_scanned, sc))
|
|
goto restart;
|
|
|
|
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),
|
|
&cpuset_current_mems_allowed,
|
|
&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
|
|
|
|
/*
|
|
* pgdat_balanced is used when checking if a node is balanced for high-order
|
|
* allocations. Only zones that meet watermarks and are in a zone allowed
|
|
* by the callers classzone_idx are added to balanced_pages. The total of
|
|
* balanced pages must be at least 25% of the zones allowed by classzone_idx
|
|
* for the node to be considered balanced. Forcing all zones to be balanced
|
|
* for high orders can cause excessive reclaim when there are imbalanced zones.
|
|
* The choice of 25% is due to
|
|
* o a 16M DMA zone that is balanced will not balance a zone on any
|
|
* reasonable sized machine
|
|
* o On all other machines, the top zone must be at least a reasonable
|
|
* precentage of the middle zones. For example, on 32-bit x86, highmem
|
|
* would need to be at least 256M for it to be balance a whole node.
|
|
* Similarly, on x86-64 the Normal zone would need to be at least 1G
|
|
* to balance a node on its own. These seemed like reasonable ratios.
|
|
*/
|
|
static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages,
|
|
int classzone_idx)
|
|
{
|
|
unsigned long present_pages = 0;
|
|
int i;
|
|
|
|
for (i = 0; i <= classzone_idx; i++)
|
|
present_pages += pgdat->node_zones[i].present_pages;
|
|
|
|
return balanced_pages > (present_pages >> 2);
|
|
}
|
|
|
|
/* is kswapd sleeping prematurely? */
|
|
static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining,
|
|
int classzone_idx)
|
|
{
|
|
int i;
|
|
unsigned long balanced = 0;
|
|
bool all_zones_ok = true;
|
|
|
|
/* If a direct reclaimer woke kswapd within HZ/10, it's premature */
|
|
if (remaining)
|
|
return true;
|
|
|
|
/* Check the watermark levels */
|
|
for (i = 0; i < pgdat->nr_zones; i++) {
|
|
struct zone *zone = pgdat->node_zones + i;
|
|
|
|
if (!populated_zone(zone))
|
|
continue;
|
|
|
|
/*
|
|
* balance_pgdat() skips over all_unreclaimable after
|
|
* DEF_PRIORITY. Effectively, it considers them balanced so
|
|
* they must be considered balanced here as well if kswapd
|
|
* is to sleep
|
|
*/
|
|
if (zone->all_unreclaimable) {
|
|
balanced += zone->present_pages;
|
|
continue;
|
|
}
|
|
|
|
if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone),
|
|
classzone_idx, 0))
|
|
all_zones_ok = false;
|
|
else
|
|
balanced += zone->present_pages;
|
|
}
|
|
|
|
/*
|
|
* For high-order requests, the balanced zones must contain at least
|
|
* 25% of the nodes pages for kswapd to sleep. For order-0, all zones
|
|
* must be balanced
|
|
*/
|
|
if (order)
|
|
return pgdat_balanced(pgdat, balanced, classzone_idx);
|
|
else
|
|
return !all_zones_ok;
|
|
}
|
|
|
|
/*
|
|
* For kswapd, balance_pgdat() will work across all this node's zones until
|
|
* they are all at high_wmark_pages(zone).
|
|
*
|
|
* Returns the final order kswapd was reclaiming at
|
|
*
|
|
* 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 *classzone_idx)
|
|
{
|
|
int all_zones_ok;
|
|
unsigned long balanced;
|
|
int priority;
|
|
int i;
|
|
int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
|
|
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--) {
|
|
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;
|
|
balanced = 0;
|
|
|
|
/*
|
|
* 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_safe(zone, order,
|
|
high_wmark_pages(zone), 0, 0)) {
|
|
end_zone = i;
|
|
*classzone_idx = 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;
|
|
unsigned long balance_gap;
|
|
|
|
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. The "too many pages" is defined
|
|
* as the high wmark plus a "gap" where the
|
|
* gap is either the low watermark or 1%
|
|
* of the zone, whichever is smaller.
|
|
*/
|
|
balance_gap = min(low_wmark_pages(zone),
|
|
(zone->present_pages +
|
|
KSWAPD_ZONE_BALANCE_GAP_RATIO-1) /
|
|
KSWAPD_ZONE_BALANCE_GAP_RATIO);
|
|
if (!zone_watermark_ok_safe(zone, order,
|
|
high_wmark_pages(zone) + balance_gap,
|
|
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_safe(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_safe(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 (i <= *classzone_idx)
|
|
balanced += zone->present_pages;
|
|
}
|
|
|
|
}
|
|
if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))
|
|
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:
|
|
|
|
/*
|
|
* order-0: All zones must meet high watermark for a balanced node
|
|
* high-order: Balanced zones must make up at least 25% of the node
|
|
* for the node to be balanced
|
|
*/
|
|
if (!(all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))) {
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* If kswapd was reclaiming at a higher order, it has the option of
|
|
* sleeping without all zones being balanced. Before it does, it must
|
|
* ensure that the watermarks for order-0 on *all* zones are met and
|
|
* that the congestion flags are cleared. The congestion flag must
|
|
* be cleared as kswapd is the only mechanism that clears the flag
|
|
* and it is potentially going to sleep here.
|
|
*/
|
|
if (order) {
|
|
for (i = 0; i <= end_zone; i++) {
|
|
struct zone *zone = pgdat->node_zones + i;
|
|
|
|
if (!populated_zone(zone))
|
|
continue;
|
|
|
|
if (zone->all_unreclaimable && priority != DEF_PRIORITY)
|
|
continue;
|
|
|
|
/* Confirm the zone is balanced for order-0 */
|
|
if (!zone_watermark_ok(zone, 0,
|
|
high_wmark_pages(zone), 0, 0)) {
|
|
order = sc.order = 0;
|
|
goto loop_again;
|
|
}
|
|
|
|
/* If balanced, clear the congested flag */
|
|
zone_clear_flag(zone, ZONE_CONGESTED);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Return the order we were reclaiming at so sleeping_prematurely()
|
|
* makes a decision on the order we were last reclaiming at. However,
|
|
* if another caller entered the allocator slow path while kswapd
|
|
* was awake, order will remain at the higher level
|
|
*/
|
|
*classzone_idx = end_zone;
|
|
return order;
|
|
}
|
|
|
|
static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx)
|
|
{
|
|
long remaining = 0;
|
|
DEFINE_WAIT(wait);
|
|
|
|
if (freezing(current) || kthread_should_stop())
|
|
return;
|
|
|
|
prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
|
|
|
|
/* Try to sleep for a short interval */
|
|
if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) {
|
|
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, classzone_idx)) {
|
|
trace_mm_vmscan_kswapd_sleep(pgdat->node_id);
|
|
|
|
/*
|
|
* vmstat counters are not perfectly accurate and the estimated
|
|
* value for counters such as NR_FREE_PAGES can deviate from the
|
|
* true value by nr_online_cpus * threshold. To avoid the zone
|
|
* watermarks being breached while under pressure, we reduce the
|
|
* per-cpu vmstat threshold while kswapd is awake and restore
|
|
* them before going back to sleep.
|
|
*/
|
|
set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold);
|
|
schedule();
|
|
set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold);
|
|
} else {
|
|
if (remaining)
|
|
count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY);
|
|
else
|
|
count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY);
|
|
}
|
|
finish_wait(&pgdat->kswapd_wait, &wait);
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
int classzone_idx;
|
|
pg_data_t *pgdat = (pg_data_t*)p;
|
|
struct task_struct *tsk = current;
|
|
|
|
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;
|
|
classzone_idx = MAX_NR_ZONES - 1;
|
|
for ( ; ; ) {
|
|
unsigned long new_order;
|
|
int new_classzone_idx;
|
|
int ret;
|
|
|
|
new_order = pgdat->kswapd_max_order;
|
|
new_classzone_idx = pgdat->classzone_idx;
|
|
pgdat->kswapd_max_order = 0;
|
|
pgdat->classzone_idx = MAX_NR_ZONES - 1;
|
|
if (order < new_order || classzone_idx > new_classzone_idx) {
|
|
/*
|
|
* Don't sleep if someone wants a larger 'order'
|
|
* allocation or has tigher zone constraints
|
|
*/
|
|
order = new_order;
|
|
classzone_idx = new_classzone_idx;
|
|
} else {
|
|
kswapd_try_to_sleep(pgdat, order, classzone_idx);
|
|
order = pgdat->kswapd_max_order;
|
|
classzone_idx = pgdat->classzone_idx;
|
|
pgdat->kswapd_max_order = 0;
|
|
pgdat->classzone_idx = MAX_NR_ZONES - 1;
|
|
}
|
|
|
|
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);
|
|
order = balance_pgdat(pgdat, order, &classzone_idx);
|
|
}
|
|
}
|
|
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, enum zone_type classzone_idx)
|
|
{
|
|
pg_data_t *pgdat;
|
|
|
|
if (!populated_zone(zone))
|
|
return;
|
|
|
|
if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
|
|
return;
|
|
pgdat = zone->zone_pgdat;
|
|
if (pgdat->kswapd_max_order < order) {
|
|
pgdat->kswapd_max_order = order;
|
|
pgdat->classzone_idx = min(pgdat->classzone_idx, classzone_idx);
|
|
}
|
|
if (!waitqueue_active(&pgdat->kswapd_wait))
|
|
return;
|
|
if (zone_watermark_ok_safe(zone, order, low_wmark_pages(zone), 0, 0))
|
|
return;
|
|
|
|
trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order);
|
|
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
|