linux/mm/swap.c
Shaohua Li 5bc7b8aca9 mm: thp: add split tail pages to shrink page list in page reclaim
In page reclaim, huge page is split.  split_huge_page() adds tail pages
to LRU list.  Since we are reclaiming a huge page, it's better we
reclaim all subpages of the huge page instead of just the head page.
This patch adds split tail pages to shrink page list so the tail pages
can be reclaimed soon.

Before this patch, run a swap workload:
  thp_fault_alloc 3492
  thp_fault_fallback 608
  thp_collapse_alloc 6
  thp_collapse_alloc_failed 0
  thp_split 916

With this patch:
  thp_fault_alloc 4085
  thp_fault_fallback 16
  thp_collapse_alloc 90
  thp_collapse_alloc_failed 0
  thp_split 1272

fallback allocation is reduced a lot.

[akpm@linux-foundation.org: fix CONFIG_SWAP=n build]
Signed-off-by: Shaohua Li <shli@fusionio.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-29 15:54:38 -07:00

883 lines
23 KiB
C

/*
* linux/mm/swap.c
*
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
*/
/*
* This file contains the default values for the operation of the
* Linux VM subsystem. Fine-tuning documentation can be found in
* Documentation/sysctl/vm.txt.
* Started 18.12.91
* Swap aging added 23.2.95, Stephen Tweedie.
* Buffermem limits added 12.3.98, Rik van Riel.
*/
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/kernel_stat.h>
#include <linux/swap.h>
#include <linux/mman.h>
#include <linux/pagemap.h>
#include <linux/pagevec.h>
#include <linux/init.h>
#include <linux/export.h>
#include <linux/mm_inline.h>
#include <linux/percpu_counter.h>
#include <linux/percpu.h>
#include <linux/cpu.h>
#include <linux/notifier.h>
#include <linux/backing-dev.h>
#include <linux/memcontrol.h>
#include <linux/gfp.h>
#include "internal.h"
/* How many pages do we try to swap or page in/out together? */
int page_cluster;
static DEFINE_PER_CPU(struct pagevec[NR_LRU_LISTS], lru_add_pvecs);
static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs);
/*
* This path almost never happens for VM activity - pages are normally
* freed via pagevecs. But it gets used by networking.
*/
static void __page_cache_release(struct page *page)
{
if (PageLRU(page)) {
struct zone *zone = page_zone(page);
struct lruvec *lruvec;
unsigned long flags;
spin_lock_irqsave(&zone->lru_lock, flags);
lruvec = mem_cgroup_page_lruvec(page, zone);
VM_BUG_ON(!PageLRU(page));
__ClearPageLRU(page);
del_page_from_lru_list(page, lruvec, page_off_lru(page));
spin_unlock_irqrestore(&zone->lru_lock, flags);
}
}
static void __put_single_page(struct page *page)
{
__page_cache_release(page);
free_hot_cold_page(page, 0);
}
static void __put_compound_page(struct page *page)
{
compound_page_dtor *dtor;
__page_cache_release(page);
dtor = get_compound_page_dtor(page);
(*dtor)(page);
}
static void put_compound_page(struct page *page)
{
if (unlikely(PageTail(page))) {
/* __split_huge_page_refcount can run under us */
struct page *page_head = compound_trans_head(page);
if (likely(page != page_head &&
get_page_unless_zero(page_head))) {
unsigned long flags;
/*
* THP can not break up slab pages so avoid taking
* compound_lock(). Slab performs non-atomic bit ops
* on page->flags for better performance. In particular
* slab_unlock() in slub used to be a hot path. It is
* still hot on arches that do not support
* this_cpu_cmpxchg_double().
*/
if (PageSlab(page_head)) {
if (PageTail(page)) {
if (put_page_testzero(page_head))
VM_BUG_ON(1);
atomic_dec(&page->_mapcount);
goto skip_lock_tail;
} else
goto skip_lock;
}
/*
* page_head wasn't a dangling pointer but it
* may not be a head page anymore by the time
* we obtain the lock. That is ok as long as it
* can't be freed from under us.
*/
flags = compound_lock_irqsave(page_head);
if (unlikely(!PageTail(page))) {
/* __split_huge_page_refcount run before us */
compound_unlock_irqrestore(page_head, flags);
skip_lock:
if (put_page_testzero(page_head))
__put_single_page(page_head);
out_put_single:
if (put_page_testzero(page))
__put_single_page(page);
return;
}
VM_BUG_ON(page_head != page->first_page);
/*
* We can release the refcount taken by
* get_page_unless_zero() now that
* __split_huge_page_refcount() is blocked on
* the compound_lock.
*/
if (put_page_testzero(page_head))
VM_BUG_ON(1);
/* __split_huge_page_refcount will wait now */
VM_BUG_ON(page_mapcount(page) <= 0);
atomic_dec(&page->_mapcount);
VM_BUG_ON(atomic_read(&page_head->_count) <= 0);
VM_BUG_ON(atomic_read(&page->_count) != 0);
compound_unlock_irqrestore(page_head, flags);
skip_lock_tail:
if (put_page_testzero(page_head)) {
if (PageHead(page_head))
__put_compound_page(page_head);
else
__put_single_page(page_head);
}
} else {
/* page_head is a dangling pointer */
VM_BUG_ON(PageTail(page));
goto out_put_single;
}
} else if (put_page_testzero(page)) {
if (PageHead(page))
__put_compound_page(page);
else
__put_single_page(page);
}
}
void put_page(struct page *page)
{
if (unlikely(PageCompound(page)))
put_compound_page(page);
else if (put_page_testzero(page))
__put_single_page(page);
}
EXPORT_SYMBOL(put_page);
/*
* This function is exported but must not be called by anything other
* than get_page(). It implements the slow path of get_page().
*/
bool __get_page_tail(struct page *page)
{
/*
* This takes care of get_page() if run on a tail page
* returned by one of the get_user_pages/follow_page variants.
* get_user_pages/follow_page itself doesn't need the compound
* lock because it runs __get_page_tail_foll() under the
* proper PT lock that already serializes against
* split_huge_page().
*/
unsigned long flags;
bool got = false;
struct page *page_head = compound_trans_head(page);
if (likely(page != page_head && get_page_unless_zero(page_head))) {
/* Ref to put_compound_page() comment. */
if (PageSlab(page_head)) {
if (likely(PageTail(page))) {
__get_page_tail_foll(page, false);
return true;
} else {
put_page(page_head);
return false;
}
}
/*
* page_head wasn't a dangling pointer but it
* may not be a head page anymore by the time
* we obtain the lock. That is ok as long as it
* can't be freed from under us.
*/
flags = compound_lock_irqsave(page_head);
/* here __split_huge_page_refcount won't run anymore */
if (likely(PageTail(page))) {
__get_page_tail_foll(page, false);
got = true;
}
compound_unlock_irqrestore(page_head, flags);
if (unlikely(!got))
put_page(page_head);
}
return got;
}
EXPORT_SYMBOL(__get_page_tail);
/**
* put_pages_list() - release a list of pages
* @pages: list of pages threaded on page->lru
*
* Release a list of pages which are strung together on page.lru. Currently
* used by read_cache_pages() and related error recovery code.
*/
void put_pages_list(struct list_head *pages)
{
while (!list_empty(pages)) {
struct page *victim;
victim = list_entry(pages->prev, struct page, lru);
list_del(&victim->lru);
page_cache_release(victim);
}
}
EXPORT_SYMBOL(put_pages_list);
/*
* get_kernel_pages() - pin kernel pages in memory
* @kiov: An array of struct kvec structures
* @nr_segs: number of segments to pin
* @write: pinning for read/write, currently ignored
* @pages: array that receives pointers to the pages pinned.
* Should be at least nr_segs long.
*
* Returns number of pages pinned. This may be fewer than the number
* requested. If nr_pages is 0 or negative, returns 0. If no pages
* were pinned, returns -errno. Each page returned must be released
* with a put_page() call when it is finished with.
*/
int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
struct page **pages)
{
int seg;
for (seg = 0; seg < nr_segs; seg++) {
if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
return seg;
pages[seg] = kmap_to_page(kiov[seg].iov_base);
page_cache_get(pages[seg]);
}
return seg;
}
EXPORT_SYMBOL_GPL(get_kernel_pages);
/*
* get_kernel_page() - pin a kernel page in memory
* @start: starting kernel address
* @write: pinning for read/write, currently ignored
* @pages: array that receives pointer to the page pinned.
* Must be at least nr_segs long.
*
* Returns 1 if page is pinned. If the page was not pinned, returns
* -errno. The page returned must be released with a put_page() call
* when it is finished with.
*/
int get_kernel_page(unsigned long start, int write, struct page **pages)
{
const struct kvec kiov = {
.iov_base = (void *)start,
.iov_len = PAGE_SIZE
};
return get_kernel_pages(&kiov, 1, write, pages);
}
EXPORT_SYMBOL_GPL(get_kernel_page);
static void pagevec_lru_move_fn(struct pagevec *pvec,
void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg),
void *arg)
{
int i;
struct zone *zone = NULL;
struct lruvec *lruvec;
unsigned long flags = 0;
for (i = 0; i < pagevec_count(pvec); i++) {
struct page *page = pvec->pages[i];
struct zone *pagezone = page_zone(page);
if (pagezone != zone) {
if (zone)
spin_unlock_irqrestore(&zone->lru_lock, flags);
zone = pagezone;
spin_lock_irqsave(&zone->lru_lock, flags);
}
lruvec = mem_cgroup_page_lruvec(page, zone);
(*move_fn)(page, lruvec, arg);
}
if (zone)
spin_unlock_irqrestore(&zone->lru_lock, flags);
release_pages(pvec->pages, pvec->nr, pvec->cold);
pagevec_reinit(pvec);
}
static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec,
void *arg)
{
int *pgmoved = arg;
if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
enum lru_list lru = page_lru_base_type(page);
list_move_tail(&page->lru, &lruvec->lists[lru]);
(*pgmoved)++;
}
}
/*
* pagevec_move_tail() must be called with IRQ disabled.
* Otherwise this may cause nasty races.
*/
static void pagevec_move_tail(struct pagevec *pvec)
{
int pgmoved = 0;
pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
__count_vm_events(PGROTATED, pgmoved);
}
/*
* Writeback is about to end against a page which has been marked for immediate
* reclaim. If it still appears to be reclaimable, move it to the tail of the
* inactive list.
*/
void rotate_reclaimable_page(struct page *page)
{
if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
!PageUnevictable(page) && PageLRU(page)) {
struct pagevec *pvec;
unsigned long flags;
page_cache_get(page);
local_irq_save(flags);
pvec = &__get_cpu_var(lru_rotate_pvecs);
if (!pagevec_add(pvec, page))
pagevec_move_tail(pvec);
local_irq_restore(flags);
}
}
static void update_page_reclaim_stat(struct lruvec *lruvec,
int file, int rotated)
{
struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
reclaim_stat->recent_scanned[file]++;
if (rotated)
reclaim_stat->recent_rotated[file]++;
}
static void __activate_page(struct page *page, struct lruvec *lruvec,
void *arg)
{
if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
int file = page_is_file_cache(page);
int lru = page_lru_base_type(page);
del_page_from_lru_list(page, lruvec, lru);
SetPageActive(page);
lru += LRU_ACTIVE;
add_page_to_lru_list(page, lruvec, lru);
__count_vm_event(PGACTIVATE);
update_page_reclaim_stat(lruvec, file, 1);
}
}
#ifdef CONFIG_SMP
static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
static void activate_page_drain(int cpu)
{
struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
if (pagevec_count(pvec))
pagevec_lru_move_fn(pvec, __activate_page, NULL);
}
void activate_page(struct page *page)
{
if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
page_cache_get(page);
if (!pagevec_add(pvec, page))
pagevec_lru_move_fn(pvec, __activate_page, NULL);
put_cpu_var(activate_page_pvecs);
}
}
#else
static inline void activate_page_drain(int cpu)
{
}
void activate_page(struct page *page)
{
struct zone *zone = page_zone(page);
spin_lock_irq(&zone->lru_lock);
__activate_page(page, mem_cgroup_page_lruvec(page, zone), NULL);
spin_unlock_irq(&zone->lru_lock);
}
#endif
/*
* Mark a page as having seen activity.
*
* inactive,unreferenced -> inactive,referenced
* inactive,referenced -> active,unreferenced
* active,unreferenced -> active,referenced
*/
void mark_page_accessed(struct page *page)
{
if (!PageActive(page) && !PageUnevictable(page) &&
PageReferenced(page) && PageLRU(page)) {
activate_page(page);
ClearPageReferenced(page);
} else if (!PageReferenced(page)) {
SetPageReferenced(page);
}
}
EXPORT_SYMBOL(mark_page_accessed);
/*
* Order of operations is important: flush the pagevec when it's already
* full, not when adding the last page, to make sure that last page is
* not added to the LRU directly when passed to this function. Because
* mark_page_accessed() (called after this when writing) only activates
* pages that are on the LRU, linear writes in subpage chunks would see
* every PAGEVEC_SIZE page activated, which is unexpected.
*/
void __lru_cache_add(struct page *page, enum lru_list lru)
{
struct pagevec *pvec = &get_cpu_var(lru_add_pvecs)[lru];
page_cache_get(page);
if (!pagevec_space(pvec))
__pagevec_lru_add(pvec, lru);
pagevec_add(pvec, page);
put_cpu_var(lru_add_pvecs);
}
EXPORT_SYMBOL(__lru_cache_add);
/**
* lru_cache_add_lru - add a page to a page list
* @page: the page to be added to the LRU.
* @lru: the LRU list to which the page is added.
*/
void lru_cache_add_lru(struct page *page, enum lru_list lru)
{
if (PageActive(page)) {
VM_BUG_ON(PageUnevictable(page));
ClearPageActive(page);
} else if (PageUnevictable(page)) {
VM_BUG_ON(PageActive(page));
ClearPageUnevictable(page);
}
VM_BUG_ON(PageLRU(page) || PageActive(page) || PageUnevictable(page));
__lru_cache_add(page, lru);
}
/**
* add_page_to_unevictable_list - add a page to the unevictable list
* @page: the page to be added to the unevictable list
*
* Add page directly to its zone's unevictable list. To avoid races with
* tasks that might be making the page evictable, through eg. munlock,
* munmap or exit, while it's not on the lru, we want to add the page
* while it's locked or otherwise "invisible" to other tasks. This is
* difficult to do when using the pagevec cache, so bypass that.
*/
void add_page_to_unevictable_list(struct page *page)
{
struct zone *zone = page_zone(page);
struct lruvec *lruvec;
spin_lock_irq(&zone->lru_lock);
lruvec = mem_cgroup_page_lruvec(page, zone);
SetPageUnevictable(page);
SetPageLRU(page);
add_page_to_lru_list(page, lruvec, LRU_UNEVICTABLE);
spin_unlock_irq(&zone->lru_lock);
}
/*
* If the page can not be invalidated, it is moved to the
* inactive list to speed up its reclaim. It is moved to the
* head of the list, rather than the tail, to give the flusher
* threads some time to write it out, as this is much more
* effective than the single-page writeout from reclaim.
*
* If the page isn't page_mapped and dirty/writeback, the page
* could reclaim asap using PG_reclaim.
*
* 1. active, mapped page -> none
* 2. active, dirty/writeback page -> inactive, head, PG_reclaim
* 3. inactive, mapped page -> none
* 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
* 5. inactive, clean -> inactive, tail
* 6. Others -> none
*
* In 4, why it moves inactive's head, the VM expects the page would
* be write it out by flusher threads as this is much more effective
* than the single-page writeout from reclaim.
*/
static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
void *arg)
{
int lru, file;
bool active;
if (!PageLRU(page))
return;
if (PageUnevictable(page))
return;
/* Some processes are using the page */
if (page_mapped(page))
return;
active = PageActive(page);
file = page_is_file_cache(page);
lru = page_lru_base_type(page);
del_page_from_lru_list(page, lruvec, lru + active);
ClearPageActive(page);
ClearPageReferenced(page);
add_page_to_lru_list(page, lruvec, lru);
if (PageWriteback(page) || PageDirty(page)) {
/*
* PG_reclaim could be raced with end_page_writeback
* It can make readahead confusing. But race window
* is _really_ small and it's non-critical problem.
*/
SetPageReclaim(page);
} else {
/*
* The page's writeback ends up during pagevec
* We moves tha page into tail of inactive.
*/
list_move_tail(&page->lru, &lruvec->lists[lru]);
__count_vm_event(PGROTATED);
}
if (active)
__count_vm_event(PGDEACTIVATE);
update_page_reclaim_stat(lruvec, file, 0);
}
/*
* Drain pages out of the cpu's pagevecs.
* Either "cpu" is the current CPU, and preemption has already been
* disabled; or "cpu" is being hot-unplugged, and is already dead.
*/
void lru_add_drain_cpu(int cpu)
{
struct pagevec *pvecs = per_cpu(lru_add_pvecs, cpu);
struct pagevec *pvec;
int lru;
for_each_lru(lru) {
pvec = &pvecs[lru - LRU_BASE];
if (pagevec_count(pvec))
__pagevec_lru_add(pvec, lru);
}
pvec = &per_cpu(lru_rotate_pvecs, cpu);
if (pagevec_count(pvec)) {
unsigned long flags;
/* No harm done if a racing interrupt already did this */
local_irq_save(flags);
pagevec_move_tail(pvec);
local_irq_restore(flags);
}
pvec = &per_cpu(lru_deactivate_pvecs, cpu);
if (pagevec_count(pvec))
pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
activate_page_drain(cpu);
}
/**
* deactivate_page - forcefully deactivate a page
* @page: page to deactivate
*
* This function hints the VM that @page is a good reclaim candidate,
* for example if its invalidation fails due to the page being dirty
* or under writeback.
*/
void deactivate_page(struct page *page)
{
/*
* In a workload with many unevictable page such as mprotect, unevictable
* page deactivation for accelerating reclaim is pointless.
*/
if (PageUnevictable(page))
return;
if (likely(get_page_unless_zero(page))) {
struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs);
if (!pagevec_add(pvec, page))
pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
put_cpu_var(lru_deactivate_pvecs);
}
}
void lru_add_drain(void)
{
lru_add_drain_cpu(get_cpu());
put_cpu();
}
static void lru_add_drain_per_cpu(struct work_struct *dummy)
{
lru_add_drain();
}
/*
* Returns 0 for success
*/
int lru_add_drain_all(void)
{
return schedule_on_each_cpu(lru_add_drain_per_cpu);
}
/*
* Batched page_cache_release(). Decrement the reference count on all the
* passed pages. If it fell to zero then remove the page from the LRU and
* free it.
*
* Avoid taking zone->lru_lock if possible, but if it is taken, retain it
* for the remainder of the operation.
*
* The locking in this function is against shrink_inactive_list(): we recheck
* the page count inside the lock to see whether shrink_inactive_list()
* grabbed the page via the LRU. If it did, give up: shrink_inactive_list()
* will free it.
*/
void release_pages(struct page **pages, int nr, int cold)
{
int i;
LIST_HEAD(pages_to_free);
struct zone *zone = NULL;
struct lruvec *lruvec;
unsigned long uninitialized_var(flags);
for (i = 0; i < nr; i++) {
struct page *page = pages[i];
if (unlikely(PageCompound(page))) {
if (zone) {
spin_unlock_irqrestore(&zone->lru_lock, flags);
zone = NULL;
}
put_compound_page(page);
continue;
}
if (!put_page_testzero(page))
continue;
if (PageLRU(page)) {
struct zone *pagezone = page_zone(page);
if (pagezone != zone) {
if (zone)
spin_unlock_irqrestore(&zone->lru_lock,
flags);
zone = pagezone;
spin_lock_irqsave(&zone->lru_lock, flags);
}
lruvec = mem_cgroup_page_lruvec(page, zone);
VM_BUG_ON(!PageLRU(page));
__ClearPageLRU(page);
del_page_from_lru_list(page, lruvec, page_off_lru(page));
}
list_add(&page->lru, &pages_to_free);
}
if (zone)
spin_unlock_irqrestore(&zone->lru_lock, flags);
free_hot_cold_page_list(&pages_to_free, cold);
}
EXPORT_SYMBOL(release_pages);
/*
* The pages which we're about to release may be in the deferred lru-addition
* queues. That would prevent them from really being freed right now. That's
* OK from a correctness point of view but is inefficient - those pages may be
* cache-warm and we want to give them back to the page allocator ASAP.
*
* So __pagevec_release() will drain those queues here. __pagevec_lru_add()
* and __pagevec_lru_add_active() call release_pages() directly to avoid
* mutual recursion.
*/
void __pagevec_release(struct pagevec *pvec)
{
lru_add_drain();
release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
pagevec_reinit(pvec);
}
EXPORT_SYMBOL(__pagevec_release);
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
/* used by __split_huge_page_refcount() */
void lru_add_page_tail(struct page *page, struct page *page_tail,
struct lruvec *lruvec, struct list_head *list)
{
int uninitialized_var(active);
enum lru_list lru;
const int file = 0;
VM_BUG_ON(!PageHead(page));
VM_BUG_ON(PageCompound(page_tail));
VM_BUG_ON(PageLRU(page_tail));
VM_BUG_ON(NR_CPUS != 1 &&
!spin_is_locked(&lruvec_zone(lruvec)->lru_lock));
if (!list)
SetPageLRU(page_tail);
if (page_evictable(page_tail)) {
if (PageActive(page)) {
SetPageActive(page_tail);
active = 1;
lru = LRU_ACTIVE_ANON;
} else {
active = 0;
lru = LRU_INACTIVE_ANON;
}
} else {
SetPageUnevictable(page_tail);
lru = LRU_UNEVICTABLE;
}
if (likely(PageLRU(page)))
list_add_tail(&page_tail->lru, &page->lru);
else if (list) {
/* page reclaim is reclaiming a huge page */
get_page(page_tail);
list_add_tail(&page_tail->lru, list);
} else {
struct list_head *list_head;
/*
* Head page has not yet been counted, as an hpage,
* so we must account for each subpage individually.
*
* Use the standard add function to put page_tail on the list,
* but then correct its position so they all end up in order.
*/
add_page_to_lru_list(page_tail, lruvec, lru);
list_head = page_tail->lru.prev;
list_move_tail(&page_tail->lru, list_head);
}
if (!PageUnevictable(page))
update_page_reclaim_stat(lruvec, file, active);
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
void *arg)
{
enum lru_list lru = (enum lru_list)arg;
int file = is_file_lru(lru);
int active = is_active_lru(lru);
VM_BUG_ON(PageActive(page));
VM_BUG_ON(PageUnevictable(page));
VM_BUG_ON(PageLRU(page));
SetPageLRU(page);
if (active)
SetPageActive(page);
add_page_to_lru_list(page, lruvec, lru);
update_page_reclaim_stat(lruvec, file, active);
}
/*
* Add the passed pages to the LRU, then drop the caller's refcount
* on them. Reinitialises the caller's pagevec.
*/
void __pagevec_lru_add(struct pagevec *pvec, enum lru_list lru)
{
VM_BUG_ON(is_unevictable_lru(lru));
pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, (void *)lru);
}
EXPORT_SYMBOL(__pagevec_lru_add);
/**
* pagevec_lookup - gang pagecache lookup
* @pvec: Where the resulting pages are placed
* @mapping: The address_space to search
* @start: The starting page index
* @nr_pages: The maximum number of pages
*
* pagevec_lookup() will search for and return a group of up to @nr_pages pages
* in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
* reference against the pages in @pvec.
*
* The search returns a group of mapping-contiguous pages with ascending
* indexes. There may be holes in the indices due to not-present pages.
*
* pagevec_lookup() returns the number of pages which were found.
*/
unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
pgoff_t start, unsigned nr_pages)
{
pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
return pagevec_count(pvec);
}
EXPORT_SYMBOL(pagevec_lookup);
unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
pgoff_t *index, int tag, unsigned nr_pages)
{
pvec->nr = find_get_pages_tag(mapping, index, tag,
nr_pages, pvec->pages);
return pagevec_count(pvec);
}
EXPORT_SYMBOL(pagevec_lookup_tag);
/*
* Perform any setup for the swap system
*/
void __init swap_setup(void)
{
unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);
#ifdef CONFIG_SWAP
int i;
bdi_init(swapper_spaces[0].backing_dev_info);
for (i = 0; i < MAX_SWAPFILES; i++) {
spin_lock_init(&swapper_spaces[i].tree_lock);
INIT_LIST_HEAD(&swapper_spaces[i].i_mmap_nonlinear);
}
#endif
/* Use a smaller cluster for small-memory machines */
if (megs < 16)
page_cluster = 2;
else
page_cluster = 3;
/*
* Right now other parts of the system means that we
* _really_ don't want to cluster much more
*/
}