aboutsummaryrefslogtreecommitdiff
path: root/mm/vmscan.c
diff options
context:
space:
mode:
authorIngo Molnar <mingo@elte.hu>2008-11-10 09:10:44 +0100
committerIngo Molnar <mingo@elte.hu>2008-11-10 09:10:44 +0100
commita5a64498c194c82ecad3a2d67cff6231cda8d3dd (patch)
tree723d5d81419f9960b8d30ed9a2ece8a58d6c4328 /mm/vmscan.c
parentbb93d802ae5c1949977cc6da247b218240677f11 (diff)
parentf7160c7573615ec82c691e294cf80d920b5d588d (diff)
Merge commit 'v2.6.28-rc4' into timers/rtc
Conflicts: drivers/rtc/rtc-cmos.c
Diffstat (limited to 'mm/vmscan.c')
-rw-r--r--mm/vmscan.c1026
1 files changed, 760 insertions, 266 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 1ff1a58e7c1..3b5860294bb 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -39,6 +39,7 @@
#include <linux/freezer.h>
#include <linux/memcontrol.h>
#include <linux/delayacct.h>
+#include <linux/sysctl.h>
#include <asm/tlbflush.h>
#include <asm/div64.h>
@@ -78,7 +79,7 @@ struct scan_control {
unsigned long (*isolate_pages)(unsigned long nr, struct list_head *dst,
unsigned long *scanned, int order, int mode,
struct zone *z, struct mem_cgroup *mem_cont,
- int active);
+ int active, int file);
};
#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
@@ -470,6 +471,85 @@ int remove_mapping(struct address_space *mapping, struct page *page)
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.
+ */
+#ifdef CONFIG_UNEVICTABLE_LRU
+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_is_file_cache(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);
+ }
+ mem_cgroup_move_lists(page, lru);
+
+ /*
+ * 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 */
+}
+
+#else /* CONFIG_UNEVICTABLE_LRU */
+
+void putback_lru_page(struct page *page)
+{
+ int lru;
+ VM_BUG_ON(PageLRU(page));
+
+ lru = !!TestClearPageActive(page) + page_is_file_cache(page);
+ lru_cache_add_lru(page, lru);
+ mem_cgroup_move_lists(page, lru);
+ put_page(page);
+}
+#endif /* CONFIG_UNEVICTABLE_LRU */
+
+
/*
* shrink_page_list() returns the number of reclaimed pages
*/
@@ -503,6 +583,9 @@ static unsigned long shrink_page_list(struct list_head *page_list,
sc->nr_scanned++;
+ if (unlikely(!page_evictable(page, NULL)))
+ goto cull_mlocked;
+
if (!sc->may_swap && page_mapped(page))
goto keep_locked;
@@ -539,9 +622,19 @@ static unsigned long shrink_page_list(struct list_head *page_list,
* Anonymous process memory has backing store?
* Try to allocate it some swap space here.
*/
- if (PageAnon(page) && !PageSwapCache(page))
+ if (PageAnon(page) && !PageSwapCache(page)) {
+ switch (try_to_munlock(page)) {
+ case SWAP_FAIL: /* shouldn't happen */
+ case SWAP_AGAIN:
+ goto keep_locked;
+ case SWAP_MLOCK:
+ goto cull_mlocked;
+ case SWAP_SUCCESS:
+ ; /* fall thru'; add to swap cache */
+ }
if (!add_to_swap(page, GFP_ATOMIC))
goto activate_locked;
+ }
#endif /* CONFIG_SWAP */
mapping = page_mapping(page);
@@ -556,6 +649,8 @@ static unsigned long shrink_page_list(struct list_head *page_list,
goto activate_locked;
case SWAP_AGAIN:
goto keep_locked;
+ case SWAP_MLOCK:
+ goto cull_mlocked;
case SWAP_SUCCESS:
; /* try to free the page below */
}
@@ -602,7 +697,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
* 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.
+ * 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.
*
@@ -637,7 +732,14 @@ static unsigned long shrink_page_list(struct list_head *page_list,
if (!mapping || !__remove_mapping(mapping, page))
goto keep_locked;
- unlock_page(page);
+ /*
+ * 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++;
if (!pagevec_add(&freed_pvec, page)) {
@@ -646,14 +748,23 @@ free_it:
}
continue;
+cull_mlocked:
+ unlock_page(page);
+ putback_lru_page(page);
+ continue;
+
activate_locked:
+ /* Not a candidate for swapping, so reclaim swap space. */
+ if (PageSwapCache(page) && vm_swap_full())
+ remove_exclusive_swap_page_ref(page);
+ VM_BUG_ON(PageActive(page));
SetPageActive(page);
pgactivate++;
keep_locked:
unlock_page(page);
keep:
list_add(&page->lru, &ret_pages);
- VM_BUG_ON(PageLRU(page));
+ VM_BUG_ON(PageLRU(page) || PageUnevictable(page));
}
list_splice(&ret_pages, page_list);
if (pagevec_count(&freed_pvec))
@@ -677,7 +788,7 @@ keep:
*
* returns 0 on success, -ve errno on failure.
*/
-int __isolate_lru_page(struct page *page, int mode)
+int __isolate_lru_page(struct page *page, int mode, int file)
{
int ret = -EINVAL;
@@ -693,6 +804,17 @@ int __isolate_lru_page(struct page *page, int mode)
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))) {
/*
@@ -723,12 +845,13 @@ int __isolate_lru_page(struct page *page, int mode)
* @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)
+ unsigned long *scanned, int order, int mode, int file)
{
unsigned long nr_taken = 0;
unsigned long scan;
@@ -745,7 +868,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
VM_BUG_ON(!PageLRU(page));
- switch (__isolate_lru_page(page, mode)) {
+ switch (__isolate_lru_page(page, mode, file)) {
case 0:
list_move(&page->lru, dst);
nr_taken++;
@@ -788,10 +911,11 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
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))
continue;
- switch (__isolate_lru_page(cursor_page, mode)) {
+ switch (__isolate_lru_page(cursor_page, mode, file)) {
case 0:
list_move(&cursor_page->lru, dst);
nr_taken++;
@@ -802,7 +926,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
/* else it is being freed elsewhere */
list_move(&cursor_page->lru, src);
default:
- break;
+ break; /* ! on LRU or wrong list */
}
}
}
@@ -816,40 +940,93 @@ static unsigned long isolate_pages_global(unsigned long nr,
unsigned long *scanned, int order,
int mode, struct zone *z,
struct mem_cgroup *mem_cont,
- int active)
+ int active, int file)
{
+ int lru = LRU_BASE;
if (active)
- return isolate_lru_pages(nr, &z->active_list, dst,
- scanned, order, mode);
- else
- return isolate_lru_pages(nr, &z->inactive_list, dst,
- scanned, order, mode);
+ 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)
+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)
+ list_for_each_entry(page, page_list, lru) {
+ lru = page_is_file_cache(page);
if (PageActive(page)) {
+ lru += LRU_ACTIVE;
ClearPageActive(page);
nr_active++;
}
+ count[lru]++;
+ }
return nr_active;
}
+/**
+ * isolate_lru_page - tries to isolate a page from its LRU list
+ * @page: page to isolate from its LRU list
+ *
+ * Isolates a @page from an LRU list, clears PageLRU and adjusts the
+ * vmstat statistic corresponding to whatever LRU list the page was on.
+ *
+ * Returns 0 if the page was removed from an LRU list.
+ * Returns -EBUSY if the page was not on an LRU list.
+ *
+ * The returned page will have PageLRU() cleared. If it was found on
+ * the active list, it will have PageActive set. If it was found on
+ * the unevictable list, it will have the PageUnevictable bit set. That flag
+ * may need to be cleared by the caller before letting the page go.
+ *
+ * The vmstat statistic corresponding to the list on which the page was
+ * found will be decremented.
+ *
+ * Restrictions:
+ * (1) Must be called with an elevated refcount on the page. This is a
+ * fundamentnal difference from isolate_lru_pages (which is called
+ * without a stable reference).
+ * (2) the lru_lock must not be held.
+ * (3) interrupts must be enabled.
+ */
+int isolate_lru_page(struct page *page)
+{
+ int ret = -EBUSY;
+
+ if (PageLRU(page)) {
+ struct zone *zone = page_zone(page);
+
+ spin_lock_irq(&zone->lru_lock);
+ if (PageLRU(page) && get_page_unless_zero(page)) {
+ int lru = page_lru(page);
+ ret = 0;
+ ClearPageLRU(page);
+
+ del_page_from_lru_list(zone, page, lru);
+ }
+ spin_unlock_irq(&zone->lru_lock);
+ }
+ return ret;
+}
+
/*
* shrink_inactive_list() is a helper for shrink_zone(). It returns the number
* of reclaimed pages
*/
static unsigned long shrink_inactive_list(unsigned long max_scan,
- struct zone *zone, struct scan_control *sc)
+ struct zone *zone, struct scan_control *sc,
+ int priority, int file)
{
LIST_HEAD(page_list);
struct pagevec pvec;
@@ -866,20 +1043,43 @@ static unsigned long shrink_inactive_list(unsigned long max_scan,
unsigned long nr_scan;
unsigned long nr_freed;
unsigned long nr_active;
+ unsigned int count[NR_LRU_LISTS] = { 0, };
+ int mode = ISOLATE_INACTIVE;
+
+ /*
+ * If we need a large contiguous chunk of memory, or have
+ * trouble getting a small set of contiguous pages, we
+ * will reclaim both active and inactive pages.
+ *
+ * We use the same threshold as pageout congestion_wait below.
+ */
+ if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
+ mode = ISOLATE_BOTH;
+ else if (sc->order && priority < DEF_PRIORITY - 2)
+ mode = ISOLATE_BOTH;
nr_taken = sc->isolate_pages(sc->swap_cluster_max,
- &page_list, &nr_scan, sc->order,
- (sc->order > PAGE_ALLOC_COSTLY_ORDER)?
- ISOLATE_BOTH : ISOLATE_INACTIVE,
- zone, sc->mem_cgroup, 0);
- nr_active = clear_active_flags(&page_list);
+ &page_list, &nr_scan, sc->order, mode,
+ zone, sc->mem_cgroup, 0, file);
+ nr_active = clear_active_flags(&page_list, count);
__count_vm_events(PGDEACTIVATE, nr_active);
- __mod_zone_page_state(zone, NR_ACTIVE, -nr_active);
- __mod_zone_page_state(zone, NR_INACTIVE,
- -(nr_taken - nr_active));
- if (scan_global_lru(sc))
+ __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]);
+
+ if (scan_global_lru(sc)) {
zone->pages_scanned += nr_scan;
+ zone->recent_scanned[0] += count[LRU_INACTIVE_ANON];
+ zone->recent_scanned[0] += count[LRU_ACTIVE_ANON];
+ zone->recent_scanned[1] += count[LRU_INACTIVE_FILE];
+ zone->recent_scanned[1] += count[LRU_ACTIVE_FILE];
+ }
spin_unlock_irq(&zone->lru_lock);
nr_scanned += nr_scan;
@@ -899,7 +1099,7 @@ static unsigned long shrink_inactive_list(unsigned long max_scan,
* The attempt at page out may have made some
* of the pages active, mark them inactive again.
*/
- nr_active = clear_active_flags(&page_list);
+ nr_active = clear_active_flags(&page_list, count);
count_vm_events(PGDEACTIVATE, nr_active);
nr_freed += shrink_page_list(&page_list, sc,
@@ -924,14 +1124,24 @@ static unsigned long shrink_inactive_list(unsigned long max_scan,
* Put back any unfreeable pages.
*/
while (!list_empty(&page_list)) {
+ int lru;
page = lru_to_page(&page_list);
VM_BUG_ON(PageLRU(page));
- SetPageLRU(page);
list_del(&page->lru);
- if (PageActive(page))
- add_page_to_active_list(zone, page);
- else
- add_page_to_inactive_list(zone, page);
+ 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);
+ mem_cgroup_move_lists(page, lru);
+ if (PageActive(page) && scan_global_lru(sc)) {
+ int file = !!page_is_file_cache(page);
+ zone->recent_rotated[file]++;
+ }
if (!pagevec_add(&pvec, page)) {
spin_unlock_irq(&zone->lru_lock);
__pagevec_release(&pvec);
@@ -962,115 +1172,7 @@ static inline void note_zone_scanning_priority(struct zone *zone, int priority)
static inline int zone_is_near_oom(struct zone *zone)
{
- return zone->pages_scanned >= (zone_page_state(zone, NR_ACTIVE)
- + zone_page_state(zone, NR_INACTIVE))*3;
-}
-
-/*
- * Determine we should try to reclaim mapped pages.
- * This is called only when sc->mem_cgroup is NULL.
- */
-static int calc_reclaim_mapped(struct scan_control *sc, struct zone *zone,
- int priority)
-{
- long mapped_ratio;
- long distress;
- long swap_tendency;
- long imbalance;
- int reclaim_mapped = 0;
- int prev_priority;
-
- if (scan_global_lru(sc) && zone_is_near_oom(zone))
- return 1;
- /*
- * `distress' is a measure of how much trouble we're having
- * reclaiming pages. 0 -> no problems. 100 -> great trouble.
- */
- if (scan_global_lru(sc))
- prev_priority = zone->prev_priority;
- else
- prev_priority = mem_cgroup_get_reclaim_priority(sc->mem_cgroup);
-
- distress = 100 >> min(prev_priority, priority);
-
- /*
- * The point of this algorithm is to decide when to start
- * reclaiming mapped memory instead of just pagecache. Work out
- * how much memory
- * is mapped.
- */
- if (scan_global_lru(sc))
- mapped_ratio = ((global_page_state(NR_FILE_MAPPED) +
- global_page_state(NR_ANON_PAGES)) * 100) /
- vm_total_pages;
- else
- mapped_ratio = mem_cgroup_calc_mapped_ratio(sc->mem_cgroup);
-
- /*
- * Now decide how much we really want to unmap some pages. The
- * mapped ratio is downgraded - just because there's a lot of
- * mapped memory doesn't necessarily mean that page reclaim
- * isn't succeeding.
- *
- * The distress ratio is important - we don't want to start
- * going oom.
- *
- * A 100% value of vm_swappiness overrides this algorithm
- * altogether.
- */
- swap_tendency = mapped_ratio / 2 + distress + sc->swappiness;
-
- /*
- * If there's huge imbalance between active and inactive
- * (think active 100 times larger than inactive) we should
- * become more permissive, or the system will take too much
- * cpu before it start swapping during memory pressure.
- * Distress is about avoiding early-oom, this is about
- * making swappiness graceful despite setting it to low
- * values.
- *
- * Avoid div by zero with nr_inactive+1, and max resulting
- * value is vm_total_pages.
- */
- if (scan_global_lru(sc)) {
- imbalance = zone_page_state(zone, NR_ACTIVE);
- imbalance /= zone_page_state(zone, NR_INACTIVE) + 1;
- } else
- imbalance = mem_cgroup_reclaim_imbalance(sc->mem_cgroup);
-
- /*
- * Reduce the effect of imbalance if swappiness is low,
- * this means for a swappiness very low, the imbalance
- * must be much higher than 100 for this logic to make
- * the difference.
- *
- * Max temporary value is vm_total_pages*100.
- */
- imbalance *= (vm_swappiness + 1);
- imbalance /= 100;
-
- /*
- * If not much of the ram is mapped, makes the imbalance
- * less relevant, it's high priority we refill the inactive
- * list with mapped pages only in presence of high ratio of
- * mapped pages.
- *
- * Max temporary value is vm_total_pages*100.
- */
- imbalance *= mapped_ratio;
- imbalance /= 100;
-
- /* apply imbalance feedback to swap_tendency */
- swap_tendency += imbalance;
-
- /*
- * Now use this metric to decide whether to start moving mapped
- * memory onto the inactive list.
- */
- if (swap_tendency >= 100)
- reclaim_mapped = 1;
-
- return reclaim_mapped;
+ return zone->pages_scanned >= (zone_lru_pages(zone) * 3);
}
/*
@@ -1093,53 +1195,71 @@ static int calc_reclaim_mapped(struct scan_control *sc, struct zone *zone,
static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
- struct scan_control *sc, int priority)
+ struct scan_control *sc, int priority, int file)
{
unsigned long pgmoved;
int pgdeactivate = 0;
unsigned long pgscanned;
LIST_HEAD(l_hold); /* The pages which were snipped off */
- LIST_HEAD(l_inactive); /* Pages to go onto the inactive_list */
- LIST_HEAD(l_active); /* Pages to go onto the active_list */
+ LIST_HEAD(l_inactive);
struct page *page;
struct pagevec pvec;
- int reclaim_mapped = 0;
-
- if (sc->may_swap)
- reclaim_mapped = calc_reclaim_mapped(sc, zone, priority);
+ enum lru_list lru;
lru_add_drain();
spin_lock_irq(&zone->lru_lock);
pgmoved = sc->isolate_pages(nr_pages, &l_hold, &pgscanned, sc->order,
ISOLATE_ACTIVE, zone,
- sc->mem_cgroup, 1);
+ sc->mem_cgroup, 1, file);
/*
* zone->pages_scanned is used for detect zone's oom
* mem_cgroup remembers nr_scan by itself.
*/
- if (scan_global_lru(sc))
+ if (scan_global_lru(sc)) {
zone->pages_scanned += pgscanned;
+ zone->recent_scanned[!!file] += pgmoved;
+ }
- __mod_zone_page_state(zone, NR_ACTIVE, -pgmoved);
+ if (file)
+ __mod_zone_page_state(zone, NR_ACTIVE_FILE, -pgmoved);
+ else
+ __mod_zone_page_state(zone, NR_ACTIVE_ANON, -pgmoved);
spin_unlock_irq(&zone->lru_lock);
+ pgmoved = 0;
while (!list_empty(&l_hold)) {
cond_resched();
page = lru_to_page(&l_hold);
list_del(&page->lru);
- if (page_mapped(page)) {
- if (!reclaim_mapped ||
- (total_swap_pages == 0 && PageAnon(page)) ||
- page_referenced(page, 0, sc->mem_cgroup)) {
- list_add(&page->lru, &l_active);
- continue;
- }
+
+ if (unlikely(!page_evictable(page, NULL))) {
+ putback_lru_page(page);
+ continue;
}
+
+ /* page_referenced clears PageReferenced */
+ if (page_mapping_inuse(page) &&
+ page_referenced(page, 0, sc->mem_cgroup))
+ pgmoved++;
+
list_add(&page->lru, &l_inactive);
}
+ /*
+ * Count referenced pages from currently used mappings as
+ * rotated, even though they are moved to the inactive list.
+ * This helps balance scan pressure between file and anonymous
+ * pages in get_scan_ratio.
+ */
+ zone->recent_rotated[!!file] += pgmoved;
+
+ /*
+ * Move the pages to the [file or anon] inactive list.
+ */
pagevec_init(&pvec, 1);
+
pgmoved = 0;
+ lru = LRU_BASE + file * LRU_FILE;
spin_lock_irq(&zone->lru_lock);
while (!list_empty(&l_inactive)) {
page = lru_to_page(&l_inactive);
@@ -1149,11 +1269,11 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
VM_BUG_ON(!PageActive(page));
ClearPageActive(page);
- list_move(&page->lru, &zone->inactive_list);
- mem_cgroup_move_lists(page, false);
+ list_move(&page->lru, &zone->lru[lru].list);
+ mem_cgroup_move_lists(page, lru);
pgmoved++;
if (!pagevec_add(&pvec, page)) {
- __mod_zone_page_state(zone, NR_INACTIVE, pgmoved);
+ __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
spin_unlock_irq(&zone->lru_lock);
pgdeactivate += pgmoved;
pgmoved = 0;
@@ -1163,104 +1283,189 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
spin_lock_irq(&zone->lru_lock);
}
}
- __mod_zone_page_state(zone, NR_INACTIVE, pgmoved);
+ __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
pgdeactivate += pgmoved;
if (buffer_heads_over_limit) {
spin_unlock_irq(&zone->lru_lock);
pagevec_strip(&pvec);
spin_lock_irq(&zone->lru_lock);
}
-
- pgmoved = 0;
- while (!list_empty(&l_active)) {
- page = lru_to_page(&l_active);
- prefetchw_prev_lru_page(page, &l_active, flags);
- VM_BUG_ON(PageLRU(page));
- SetPageLRU(page);
- VM_BUG_ON(!PageActive(page));
-
- list_move(&page->lru, &zone->active_list);
- mem_cgroup_move_lists(page, true);
- pgmoved++;
- if (!pagevec_add(&pvec, page)) {
- __mod_zone_page_state(zone, NR_ACTIVE, pgmoved);
- pgmoved = 0;
- spin_unlock_irq(&zone->lru_lock);
- __pagevec_release(&pvec);
- spin_lock_irq(&zone->lru_lock);
- }
- }
- __mod_zone_page_state(zone, NR_ACTIVE, pgmoved);
-
__count_zone_vm_events(PGREFILL, zone, pgscanned);
__count_vm_events(PGDEACTIVATE, pgdeactivate);
spin_unlock_irq(&zone->lru_lock);
+ if (vm_swap_full())
+ pagevec_swap_free(&pvec);
pagevec_release(&pvec);
}
+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 (lru == LRU_ACTIVE_FILE) {
+ shrink_active_list(nr_to_scan, zone, sc, priority, file);
+ return 0;
+ }
+
+ if (lru == LRU_ACTIVE_ANON &&
+ (!scan_global_lru(sc) || inactive_anon_is_low(zone))) {
+ shrink_active_list(nr_to_scan, zone, sc, priority, file);
+ return 0;
+ }
+ return shrink_inactive_list(nr_to_scan, zone, sc, priority, file);
+}
+
+/*
+ * 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.
+ *
+ * percent[0] specifies how much pressure to put on ram/swap backed
+ * memory, while percent[1] determines pressure on the file LRUs.
+ */
+static void get_scan_ratio(struct zone *zone, struct scan_control *sc,
+ unsigned long *percent)
+{
+ unsigned long anon, file, free;
+ unsigned long anon_prio, file_prio;
+ unsigned long ap, fp;
+
+ anon = zone_page_state(zone, NR_ACTIVE_ANON) +
+ zone_page_state(zone, NR_INACTIVE_ANON);
+ file = zone_page_state(zone, NR_ACTIVE_FILE) +
+ zone_page_state(zone, NR_INACTIVE_FILE);
+ free = zone_page_state(zone, NR_FREE_PAGES);
+
+ /* If we have no swap space, do not bother scanning anon pages. */
+ if (nr_swap_pages <= 0) {
+ percent[0] = 0;
+ percent[1] = 100;
+ return;
+ }
+
+ /* If we have very few page cache pages, force-scan anon pages. */
+ if (unlikely(file + free <= zone->pages_high)) {
+ percent[0] = 100;
+ percent[1] = 0;
+ return;
+ }
+
+ /*
+ * 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]
+ */
+ if (unlikely(zone->recent_scanned[0] > anon / 4)) {
+ spin_lock_irq(&zone->lru_lock);
+ zone->recent_scanned[0] /= 2;
+ zone->recent_rotated[0] /= 2;
+ spin_unlock_irq(&zone->lru_lock);
+ }
+
+ if (unlikely(zone->recent_scanned[1] > file / 4)) {
+ spin_lock_irq(&zone->lru_lock);
+ zone->recent_scanned[1] /= 2;
+ zone->recent_rotated[1] /= 2;
+ spin_unlock_irq(&zone->lru_lock);
+ }
+
+ /*
+ * 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;
+
+ /*
+ * anon recent_rotated[0]
+ * %anon = 100 * ----------- / ----------------- * IO cost
+ * anon + file rotate_sum
+ */
+ ap = (anon_prio + 1) * (zone->recent_scanned[0] + 1);
+ ap /= zone->recent_rotated[0] + 1;
+
+ fp = (file_prio + 1) * (zone->recent_scanned[1] + 1);
+ fp /= zone->recent_rotated[1] + 1;
+
+ /* Normalize to percentages */
+ percent[0] = 100 * ap / (ap + fp + 1);
+ percent[1] = 100 - percent[0];
+}
+
+
/*
* This is a basic per-zone page freer. Used by both kswapd and direct reclaim.
*/
static unsigned long shrink_zone(int priority, struct zone *zone,
struct scan_control *sc)
{
- unsigned long nr_active;
- unsigned long nr_inactive;
+ unsigned long nr[NR_LRU_LISTS];
unsigned long nr_to_scan;
unsigned long nr_reclaimed = 0;
+ unsigned long percent[2]; /* anon @ 0; file @ 1 */
+ enum lru_list l;
- if (scan_global_lru(sc)) {
- /*
- * Add one to nr_to_scan just to make sure that the kernel
- * will slowly sift through the active list.
- */
- zone->nr_scan_active +=
- (zone_page_state(zone, NR_ACTIVE) >> priority) + 1;
- nr_active = zone->nr_scan_active;
- zone->nr_scan_inactive +=
- (zone_page_state(zone, NR_INACTIVE) >> priority) + 1;
- nr_inactive = zone->nr_scan_inactive;
- if (nr_inactive >= sc->swap_cluster_max)
- zone->nr_scan_inactive = 0;
- else
- nr_inactive = 0;
-
- if (nr_active >= sc->swap_cluster_max)
- zone->nr_scan_active = 0;
- else
- nr_active = 0;
- } else {
- /*
- * This reclaim occurs not because zone memory shortage but
- * because memory controller hits its limit.
- * Then, don't modify zone reclaim related data.
- */
- nr_active = mem_cgroup_calc_reclaim_active(sc->mem_cgroup,
- zone, priority);
-
- nr_inactive = mem_cgroup_calc_reclaim_inactive(sc->mem_cgroup,
- zone, priority);
- }
+ get_scan_ratio(zone, sc, percent);
+ for_each_evictable_lru(l) {
+ if (scan_global_lru(sc)) {
+ int file = is_file_lru(l);
+ int scan;
- while (nr_active || nr_inactive) {
- if (nr_active) {
- nr_to_scan = min(nr_active,
- (unsigned long)sc->swap_cluster_max);
- nr_active -= nr_to_scan;
- shrink_active_list(nr_to_scan, zone, sc, priority);
+ scan = zone_page_state(zone, NR_LRU_BASE + l);
+ if (priority) {
+ scan >>= priority;
+ scan = (scan * percent[file]) / 100;
+ }
+ zone->lru[l].nr_scan += scan;
+ nr[l] = zone->lru[l].nr_scan;
+ if (nr[l] >= sc->swap_cluster_max)
+ zone->lru[l].nr_scan = 0;
+ else
+ nr[l] = 0;
+ } else {
+ /*
+ * This reclaim occurs not because zone memory shortage
+ * but because memory controller hits its limit.
+ * Don't modify zone reclaim related data.
+ */
+ nr[l] = mem_cgroup_calc_reclaim(sc->mem_cgroup, zone,
+ priority, l);
}
+ }
- if (nr_inactive) {
- nr_to_scan = min(nr_inactive,
+ 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(nr[l],
(unsigned long)sc->swap_cluster_max);
- nr_inactive -= nr_to_scan;
- nr_reclaimed += shrink_inactive_list(nr_to_scan, zone,
- sc);
+ nr[l] -= nr_to_scan;
+
+ nr_reclaimed += shrink_list(l, nr_to_scan,
+ zone, sc, priority);
+ }
}
}
+ /*
+ * Even if we did not try to evict anon pages at all, we want to
+ * rebalance the anon lru active/inactive ratio.
+ */
+ if (!scan_global_lru(sc) || inactive_anon_is_low(zone))
+ shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0);
+ else if (!scan_global_lru(sc))
+ shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0);
+
throttle_vm_writeout(sc->gfp_mask);
return nr_reclaimed;
}
@@ -1321,7 +1526,7 @@ static unsigned long shrink_zones(int priority, struct zonelist *zonelist,
return nr_reclaimed;
}
-
+
/*
* This is the main entry point to direct page reclaim.
*
@@ -1364,8 +1569,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
continue;
- lru_pages += zone_page_state(zone, NR_ACTIVE)
- + zone_page_state(zone, NR_INACTIVE);
+ lru_pages += zone_lru_pages(zone);
}
}
@@ -1555,6 +1759,14 @@ loop_again:
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))
+ shrink_active_list(SWAP_CLUSTER_MAX, zone,
+ &sc, priority, 0);
+
if (!zone_watermark_ok(zone, order, zone->pages_high,
0, 0)) {
end_zone = i;
@@ -1567,8 +1779,7 @@ loop_again:
for (i = 0; i <= end_zone; i++) {
struct zone *zone = pgdat->node_zones + i;
- lru_pages += zone_page_state(zone, NR_ACTIVE)
- + zone_page_state(zone, NR_INACTIVE);
+ lru_pages += zone_lru_pages(zone);
}
/*
@@ -1612,8 +1823,7 @@ loop_again:
if (zone_is_all_unreclaimable(zone))
continue;
if (nr_slab == 0 && zone->pages_scanned >=
- (zone_page_state(zone, NR_ACTIVE)
- + zone_page_state(zone, NR_INACTIVE)) * 6)
+ (zone_lru_pages(zone) * 6))
zone_set_flag(zone,
ZONE_ALL_UNRECLAIMABLE);
/*
@@ -1667,7 +1877,7 @@ out:
/*
* The background pageout daemon, started as a kernel thread
- * from the init process.
+ * from the init process.
*
* This basically trickles out pages so that we have _some_
* free memory available even if there is no other activity
@@ -1761,6 +1971,14 @@ void wakeup_kswapd(struct zone *zone, int order)
wake_up_interruptible(&pgdat->kswapd_wait);
}
+unsigned long global_lru_pages(void)
+{
+ return global_page_state(NR_ACTIVE_ANON)
+ + global_page_state(NR_ACTIVE_FILE)
+ + global_page_state(NR_INACTIVE_ANON)
+ + global_page_state(NR_INACTIVE_FILE);
+}
+
#ifdef CONFIG_PM
/*
* Helper function for shrink_all_memory(). Tries to reclaim 'nr_pages' pages
@@ -1774,6 +1992,7 @@ static unsigned long shrink_all_zones(unsigned long nr_pages, int prio,
{
struct zone *zone;
unsigned long nr_to_scan, ret = 0;
+ enum lru_list l;
for_each_zone(zone) {
@@ -1783,38 +2002,31 @@ static unsigned long shrink_all_zones(unsigned long nr_pages, int prio,
if (zone_is_all_unreclaimable(zone) && prio != DEF_PRIORITY)
continue;
- /* For pass = 0 we don't shrink the active list */
- if (pass > 0) {
- zone->nr_scan_active +=
- (zone_page_state(zone, NR_ACTIVE) >> prio) + 1;
- if (zone->nr_scan_active >= nr_pages || pass > 3) {
- zone->nr_scan_active = 0;
+ for_each_evictable_lru(l) {
+ /* For pass = 0, we don't shrink the active list */
+ if (pass == 0 &&
+ (l == LRU_ACTIVE || l == LRU_ACTIVE_FILE))
+ continue;
+
+ zone->lru[l].nr_scan +=
+ (zone_page_state(zone, NR_LRU_BASE + l)
+ >> prio) + 1;
+ if (zone->lru[l].nr_scan >= nr_pages || pass > 3) {
+ zone->lru[l].nr_scan = 0;
nr_to_scan = min(nr_pages,
- zone_page_state(zone, NR_ACTIVE));
- shrink_active_list(nr_to_scan, zone, sc, prio);
+ zone_page_state(zone,
+ NR_LRU_BASE + l));
+ ret += shrink_list(l, nr_to_scan, zone,
+ sc, prio);
+ if (ret >= nr_pages)
+ return ret;
}
}
-
- zone->nr_scan_inactive +=
- (zone_page_state(zone, NR_INACTIVE) >> prio) + 1;
- if (zone->nr_scan_inactive >= nr_pages || pass > 3) {
- zone->nr_scan_inactive = 0;
- nr_to_scan = min(nr_pages,
- zone_page_state(zone, NR_INACTIVE));
- ret += shrink_inactive_list(nr_to_scan, zone, sc);
- if (ret >= nr_pages)
- return ret;
- }
}
return ret;
}
-static unsigned long count_lru_pages(void)
-{
- return global_page_state(NR_ACTIVE) + global_page_state(NR_INACTIVE);
-}
-
/*
* Try to free `nr_pages' of memory, system-wide, and return the number of
* freed pages.
@@ -1840,7 +2052,7 @@ unsigned long shrink_all_memory(unsigned long nr_pages)
current->reclaim_state = &reclaim_state;
- lru_pages = count_lru_pages();
+ lru_pages = global_lru_pages();
nr_slab = global_page_state(NR_SLAB_RECLAIMABLE);
/* If slab caches are huge, it's better to hit them first */
while (nr_slab >= lru_pages) {
@@ -1883,7 +2095,7 @@ unsigned long shrink_all_memory(unsigned long nr_pages)
reclaim_state.reclaimed_slab = 0;
shrink_slab(sc.nr_scanned, sc.gfp_mask,
- count_lru_pages());
+ global_lru_pages());
ret += reclaim_state.reclaimed_slab;
if (ret >= nr_pages)
goto out;
@@ -1900,7 +2112,7 @@ unsigned long shrink_all_memory(unsigned long nr_pages)
if (!ret) {
do {
reclaim_state.reclaimed_slab = 0;
- shrink_slab(nr_pages, sc.gfp_mask, count_lru_pages());
+ shrink_slab(nr_pages, sc.gfp_mask, global_lru_pages());
ret += reclaim_state.reclaimed_slab;
} while (ret < nr_pages && reclaim_state.reclaimed_slab > 0);
}
@@ -2128,3 +2340,285 @@ int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
return ret;
}
#endif
+
+#ifdef CONFIG_UNEVICTABLE_LRU
+/*
+ * 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;
+}
+
+static void show_page_path(struct page *page)
+{
+ char buf[256];
+ if (page_is_file_cache(page)) {
+ struct address_space *mapping = page->mapping;
+ struct dentry *dentry;
+ pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
+
+ spin_lock(&mapping->i_mmap_lock);
+ dentry = d_find_alias(mapping->host);
+ printk(KERN_INFO "rescued: %s %lu\n",
+ dentry_path(dentry, buf, 256), pgoff);
+ spin_unlock(&mapping->i_mmap_lock);
+ } else {
+#if defined(CONFIG_MM_OWNER) && defined(CONFIG_MMU)
+ struct anon_vma *anon_vma;
+ struct vm_area_struct *vma;
+
+ anon_vma = page_lock_anon_vma(page);
+ if (!anon_vma)
+ return;
+
+ list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
+ printk(KERN_INFO "rescued: anon %s\n",
+ vma->vm_mm->owner->comm);
+ break;
+ }
+ page_unlock_anon_vma(anon_vma);
+#endif
+ }
+}
+
+
+/**
+ * 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 = LRU_INACTIVE_ANON + page_is_file_cache(page);
+
+ show_page_path(page);
+
+ __dec_zone_state(zone, NR_UNEVICTABLE);
+ list_move(&page->lru, &zone->lru[l].list);
+ __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);
+ 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 */
+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.
+ */
+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,
+ struct file *file, void __user *buffer,
+ size_t *length, loff_t *ppos)
+{
+ proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
+
+ if (write && *(unsigned long *)table->data)
+ scan_all_zones_unevictable_pages();
+
+ scan_unevictable_pages = 0;
+ return 0;
+}
+
+/*
+ * 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