#include <linux/mm_inline.h>
#include <linux/backing-dev.h>
#include <linux/sysctl.h>
+#include <linux/sysfs.h>
+#include <linux/balloon_compaction.h>
+#include <linux/page-isolation.h>
#include "internal.h"
-/*
- * compact_control is used to track pages being migrated and the free pages
- * they are being migrated to during memory compaction. The free_pfn starts
- * at the end of a zone and migrate_pfn begins at the start. Movable pages
- * are moved to the end of a zone during a compaction run and the run
- * completes when free_pfn <= migrate_pfn
- */
-struct compact_control {
- struct list_head freepages; /* List of free pages to migrate to */
- struct list_head migratepages; /* List of pages being migrated */
- unsigned long nr_freepages; /* Number of isolated free pages */
- unsigned long nr_migratepages; /* Number of pages to migrate */
- unsigned long free_pfn; /* isolate_freepages search base */
- unsigned long migrate_pfn; /* isolate_migratepages search base */
-
- /* Account for isolated anon and file pages */
- unsigned long nr_anon;
- unsigned long nr_file;
+#ifdef CONFIG_COMPACTION
+static inline void count_compact_event(enum vm_event_item item)
+{
+ count_vm_event(item);
+}
- struct zone *zone;
-};
+static inline void count_compact_events(enum vm_event_item item, long delta)
+{
+ count_vm_events(item, delta);
+}
+#else
+#define count_compact_event(item) do { } while (0)
+#define count_compact_events(item, delta) do { } while (0)
+#endif
+
+#if defined CONFIG_COMPACTION || defined CONFIG_CMA
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/compaction.h>
static unsigned long release_freepages(struct list_head *freelist)
{
return count;
}
-/* Isolate free pages onto a private freelist. Must hold zone->lock */
-static unsigned long isolate_freepages_block(struct zone *zone,
- unsigned long blockpfn,
- struct list_head *freelist)
+static void map_pages(struct list_head *list)
{
- unsigned long zone_end_pfn, end_pfn;
- int total_isolated = 0;
- struct page *cursor;
-
- /* Get the last PFN we should scan for free pages at */
- zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
- end_pfn = min(blockpfn + pageblock_nr_pages, zone_end_pfn);
+ struct page *page;
- /* Find the first usable PFN in the block to initialse page cursor */
- for (; blockpfn < end_pfn; blockpfn++) {
- if (pfn_valid_within(blockpfn))
- break;
+ list_for_each_entry(page, list, lru) {
+ arch_alloc_page(page, 0);
+ kernel_map_pages(page, 1, 1);
}
- cursor = pfn_to_page(blockpfn);
+}
- /* Isolate free pages. This assumes the block is valid */
- for (; blockpfn < end_pfn; blockpfn++, cursor++) {
- int isolated, i;
- struct page *page = cursor;
+static inline bool migrate_async_suitable(int migratetype)
+{
+ return is_migrate_cma(migratetype) || migratetype == MIGRATE_MOVABLE;
+}
- if (!pfn_valid_within(blockpfn))
+#ifdef CONFIG_COMPACTION
+/* Returns true if the pageblock should be scanned for pages to isolate. */
+static inline bool isolation_suitable(struct compact_control *cc,
+ struct page *page)
+{
+ if (cc->ignore_skip_hint)
+ return true;
+
+ return !get_pageblock_skip(page);
+}
+
+/*
+ * This function is called to clear all cached information on pageblocks that
+ * should be skipped for page isolation when the migrate and free page scanner
+ * meet.
+ */
+static void __reset_isolation_suitable(struct zone *zone)
+{
+ unsigned long start_pfn = zone->zone_start_pfn;
+ unsigned long end_pfn = zone_end_pfn(zone);
+ unsigned long pfn;
+
+ zone->compact_cached_migrate_pfn = start_pfn;
+ zone->compact_cached_free_pfn = end_pfn;
+ zone->compact_blockskip_flush = false;
+
+ /* Walk the zone and mark every pageblock as suitable for isolation */
+ for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
+ struct page *page;
+
+ cond_resched();
+
+ if (!pfn_valid(pfn))
continue;
- if (!PageBuddy(page))
+ page = pfn_to_page(pfn);
+ if (zone != page_zone(page))
continue;
- /* Found a free page, break it into order-0 pages */
- isolated = split_free_page(page);
- total_isolated += isolated;
- for (i = 0; i < isolated; i++) {
- list_add(&page->lru, freelist);
- page++;
+ clear_pageblock_skip(page);
+ }
+}
+
+void reset_isolation_suitable(pg_data_t *pgdat)
+{
+ int zoneid;
+
+ for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
+ struct zone *zone = &pgdat->node_zones[zoneid];
+ if (!populated_zone(zone))
+ continue;
+
+ /* Only flush if a full compaction finished recently */
+ if (zone->compact_blockskip_flush)
+ __reset_isolation_suitable(zone);
+ }
+}
+
+/*
+ * If no pages were isolated then mark this pageblock to be skipped in the
+ * future. The information is later cleared by __reset_isolation_suitable().
+ */
+static void update_pageblock_skip(struct compact_control *cc,
+ struct page *page, unsigned long nr_isolated,
+ bool migrate_scanner)
+{
+ struct zone *zone = cc->zone;
+ if (!page)
+ return;
+
+ if (!nr_isolated) {
+ unsigned long pfn = page_to_pfn(page);
+ set_pageblock_skip(page);
+
+ /* Update where compaction should restart */
+ if (migrate_scanner) {
+ if (!cc->finished_update_migrate &&
+ pfn > zone->compact_cached_migrate_pfn)
+ zone->compact_cached_migrate_pfn = pfn;
+ } else {
+ if (!cc->finished_update_free &&
+ pfn < zone->compact_cached_free_pfn)
+ zone->compact_cached_free_pfn = pfn;
}
+ }
+}
+#else
+static inline bool isolation_suitable(struct compact_control *cc,
+ struct page *page)
+{
+ return true;
+}
- /* If a page was split, advance to the end of it */
- if (isolated) {
- blockpfn += isolated - 1;
- cursor += isolated - 1;
+static void update_pageblock_skip(struct compact_control *cc,
+ struct page *page, unsigned long nr_isolated,
+ bool migrate_scanner)
+{
+}
+#endif /* CONFIG_COMPACTION */
+
+static inline bool should_release_lock(spinlock_t *lock)
+{
+ return need_resched() || spin_is_contended(lock);
+}
+
+/*
+ * Compaction requires the taking of some coarse locks that are potentially
+ * very heavily contended. Check if the process needs to be scheduled or
+ * if the lock is contended. For async compaction, back out in the event
+ * if contention is severe. For sync compaction, schedule.
+ *
+ * Returns true if the lock is held.
+ * Returns false if the lock is released and compaction should abort
+ */
+static bool compact_checklock_irqsave(spinlock_t *lock, unsigned long *flags,
+ bool locked, struct compact_control *cc)
+{
+ if (should_release_lock(lock)) {
+ if (locked) {
+ spin_unlock_irqrestore(lock, *flags);
+ locked = false;
+ }
+
+ /* async aborts if taking too long or contended */
+ if (!cc->sync) {
+ cc->contended = true;
+ return false;
}
+
+ cond_resched();
}
- return total_isolated;
+ if (!locked)
+ spin_lock_irqsave(lock, *flags);
+ return true;
+}
+
+static inline bool compact_trylock_irqsave(spinlock_t *lock,
+ unsigned long *flags, struct compact_control *cc)
+{
+ return compact_checklock_irqsave(lock, flags, false, cc);
}
/* Returns true if the page is within a block suitable for migration to */
static bool suitable_migration_target(struct page *page)
{
-
int migratetype = get_pageblock_migratetype(page);
/* Don't interfere with memory hot-remove or the min_free_kbytes blocks */
- if (migratetype == MIGRATE_ISOLATE || migratetype == MIGRATE_RESERVE)
+ if (migratetype == MIGRATE_RESERVE)
+ return false;
+
+ if (is_migrate_isolate(migratetype))
return false;
/* If the page is a large free page, then allow migration */
if (PageBuddy(page) && page_order(page) >= pageblock_order)
return true;
- /* If the block is MIGRATE_MOVABLE, allow migration */
- if (migratetype == MIGRATE_MOVABLE)
+ /* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */
+ if (migrate_async_suitable(migratetype))
return true;
/* Otherwise skip the block */
}
/*
- * Based on information in the current compact_control, find blocks
- * suitable for isolating free pages from and then isolate them.
+ * Isolate free pages onto a private freelist. Caller must hold zone->lock.
+ * If @strict is true, will abort returning 0 on any invalid PFNs or non-free
+ * pages inside of the pageblock (even though it may still end up isolating
+ * some pages).
*/
-static void isolate_freepages(struct zone *zone,
- struct compact_control *cc)
+static unsigned long isolate_freepages_block(struct compact_control *cc,
+ unsigned long blockpfn,
+ unsigned long end_pfn,
+ struct list_head *freelist,
+ bool strict)
{
- struct page *page;
- unsigned long high_pfn, low_pfn, pfn;
+ int nr_scanned = 0, total_isolated = 0;
+ struct page *cursor, *valid_page = NULL;
+ unsigned long nr_strict_required = end_pfn - blockpfn;
unsigned long flags;
- int nr_freepages = cc->nr_freepages;
- struct list_head *freelist = &cc->freepages;
+ bool locked = false;
- pfn = cc->free_pfn;
- low_pfn = cc->migrate_pfn + pageblock_nr_pages;
- high_pfn = low_pfn;
+ cursor = pfn_to_page(blockpfn);
- /*
- * Isolate free pages until enough are available to migrate the
- * pages on cc->migratepages. We stop searching if the migrate
- * and free page scanners meet or enough free pages are isolated.
- */
- spin_lock_irqsave(&zone->lock, flags);
- for (; pfn > low_pfn && cc->nr_migratepages > nr_freepages;
- pfn -= pageblock_nr_pages) {
- unsigned long isolated;
+ /* Isolate free pages. */
+ for (; blockpfn < end_pfn; blockpfn++, cursor++) {
+ int isolated, i;
+ struct page *page = cursor;
- if (!pfn_valid(pfn))
+ nr_scanned++;
+ if (!pfn_valid_within(blockpfn))
+ continue;
+ if (!valid_page)
+ valid_page = page;
+ if (!PageBuddy(page))
continue;
/*
- * Check for overlapping nodes/zones. It's possible on some
- * configurations to have a setup like
- * node0 node1 node0
- * i.e. it's possible that all pages within a zones range of
- * pages do not belong to a single zone.
+ * The zone lock must be held to isolate freepages.
+ * Unfortunately this is a very coarse lock and can be
+ * heavily contended if there are parallel allocations
+ * or parallel compactions. For async compaction do not
+ * spin on the lock and we acquire the lock as late as
+ * possible.
*/
- page = pfn_to_page(pfn);
- if (page_zone(page) != zone)
- continue;
+ locked = compact_checklock_irqsave(&cc->zone->lock, &flags,
+ locked, cc);
+ if (!locked)
+ break;
- /* Check the block is suitable for migration */
- if (!suitable_migration_target(page))
+ /* Recheck this is a suitable migration target under lock */
+ if (!strict && !suitable_migration_target(page))
+ break;
+
+ /* Recheck this is a buddy page under lock */
+ if (!PageBuddy(page))
continue;
- /* Found a block suitable for isolating free pages from */
- isolated = isolate_freepages_block(zone, pfn, freelist);
- nr_freepages += isolated;
+ /* Found a free page, break it into order-0 pages */
+ isolated = split_free_page(page);
+ if (!isolated && strict)
+ break;
+ total_isolated += isolated;
+ for (i = 0; i < isolated; i++) {
+ list_add(&page->lru, freelist);
+ page++;
+ }
+
+ /* If a page was split, advance to the end of it */
+ if (isolated) {
+ blockpfn += isolated - 1;
+ cursor += isolated - 1;
+ }
+ }
+
+ trace_mm_compaction_isolate_freepages(nr_scanned, total_isolated);
+
+ /*
+ * If strict isolation is requested by CMA then check that all the
+ * pages requested were isolated. If there were any failures, 0 is
+ * returned and CMA will fail.
+ */
+ if (strict && nr_strict_required > total_isolated)
+ total_isolated = 0;
+
+ if (locked)
+ spin_unlock_irqrestore(&cc->zone->lock, flags);
+
+ /* Update the pageblock-skip if the whole pageblock was scanned */
+ if (blockpfn == end_pfn)
+ update_pageblock_skip(cc, valid_page, total_isolated, false);
+
+ count_compact_events(COMPACTFREE_SCANNED, nr_scanned);
+ if (total_isolated)
+ count_compact_events(COMPACTISOLATED, total_isolated);
+ return total_isolated;
+}
+
+/**
+ * isolate_freepages_range() - isolate free pages.
+ * @start_pfn: The first PFN to start isolating.
+ * @end_pfn: The one-past-last PFN.
+ *
+ * Non-free pages, invalid PFNs, or zone boundaries within the
+ * [start_pfn, end_pfn) range are considered errors, cause function to
+ * undo its actions and return zero.
+ *
+ * Otherwise, function returns one-past-the-last PFN of isolated page
+ * (which may be greater then end_pfn if end fell in a middle of
+ * a free page).
+ */
+unsigned long
+isolate_freepages_range(struct compact_control *cc,
+ unsigned long start_pfn, unsigned long end_pfn)
+{
+ unsigned long isolated, pfn, block_end_pfn;
+ LIST_HEAD(freelist);
+
+ for (pfn = start_pfn; pfn < end_pfn; pfn += isolated) {
+ if (!pfn_valid(pfn) || cc->zone != page_zone(pfn_to_page(pfn)))
+ break;
/*
- * Record the highest PFN we isolated pages from. When next
- * looking for free pages, the search will restart here as
- * page migration may have returned some pages to the allocator
+ * On subsequent iterations ALIGN() is actually not needed,
+ * but we keep it that we not to complicate the code.
+ */
+ block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
+ block_end_pfn = min(block_end_pfn, end_pfn);
+
+ isolated = isolate_freepages_block(cc, pfn, block_end_pfn,
+ &freelist, true);
+
+ /*
+ * In strict mode, isolate_freepages_block() returns 0 if
+ * there are any holes in the block (ie. invalid PFNs or
+ * non-free pages).
+ */
+ if (!isolated)
+ break;
+
+ /*
+ * If we managed to isolate pages, it is always (1 << n) *
+ * pageblock_nr_pages for some non-negative n. (Max order
+ * page may span two pageblocks).
*/
- if (isolated)
- high_pfn = max(high_pfn, pfn);
}
- spin_unlock_irqrestore(&zone->lock, flags);
/* split_free_page does not map the pages */
- list_for_each_entry(page, freelist, lru) {
- arch_alloc_page(page, 0);
- kernel_map_pages(page, 1, 1);
+ map_pages(&freelist);
+
+ if (pfn < end_pfn) {
+ /* Loop terminated early, cleanup. */
+ release_freepages(&freelist);
+ return 0;
}
- cc->free_pfn = high_pfn;
- cc->nr_freepages = nr_freepages;
+ /* We don't use freelists for anything. */
+ return pfn;
}
/* Update the number of anon and file isolated pages in the zone */
-static void acct_isolated(struct zone *zone, struct compact_control *cc)
+static void acct_isolated(struct zone *zone, bool locked, struct compact_control *cc)
{
struct page *page;
- unsigned int count[NR_LRU_LISTS] = { 0, };
+ unsigned int count[2] = { 0, };
- list_for_each_entry(page, &cc->migratepages, lru) {
- int lru = page_lru_base_type(page);
- count[lru]++;
+ list_for_each_entry(page, &cc->migratepages, lru)
+ count[!!page_is_file_cache(page)]++;
+
+ /* If locked we can use the interrupt unsafe versions */
+ if (locked) {
+ __mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]);
+ __mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]);
+ } else {
+ mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]);
+ mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]);
}
-
- cc->nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON];
- cc->nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE];
- __mod_zone_page_state(zone, NR_ISOLATED_ANON, cc->nr_anon);
- __mod_zone_page_state(zone, NR_ISOLATED_FILE, cc->nr_file);
}
/* Similar to reclaim, but different enough that they don't share logic */
static bool too_many_isolated(struct zone *zone)
{
-
- unsigned long inactive, isolated;
+ unsigned long active, inactive, isolated;
inactive = zone_page_state(zone, NR_INACTIVE_FILE) +
zone_page_state(zone, NR_INACTIVE_ANON);
+ active = zone_page_state(zone, NR_ACTIVE_FILE) +
+ zone_page_state(zone, NR_ACTIVE_ANON);
isolated = zone_page_state(zone, NR_ISOLATED_FILE) +
zone_page_state(zone, NR_ISOLATED_ANON);
- return isolated > inactive;
+ return isolated > (inactive + active) / 2;
}
-/*
- * Isolate all pages that can be migrated from the block pointed to by
- * the migrate scanner within compact_control.
+/**
+ * isolate_migratepages_range() - isolate all migrate-able pages in range.
+ * @zone: Zone pages are in.
+ * @cc: Compaction control structure.
+ * @low_pfn: The first PFN of the range.
+ * @end_pfn: The one-past-the-last PFN of the range.
+ * @unevictable: true if it allows to isolate unevictable pages
+ *
+ * Isolate all pages that can be migrated from the range specified by
+ * [low_pfn, end_pfn). Returns zero if there is a fatal signal
+ * pending), otherwise PFN of the first page that was not scanned
+ * (which may be both less, equal to or more then end_pfn).
+ *
+ * Assumes that cc->migratepages is empty and cc->nr_migratepages is
+ * zero.
+ *
+ * Apart from cc->migratepages and cc->nr_migratetypes this function
+ * does not modify any cc's fields, in particular it does not modify
+ * (or read for that matter) cc->migrate_pfn.
*/
-static unsigned long isolate_migratepages(struct zone *zone,
- struct compact_control *cc)
+unsigned long
+isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
+ unsigned long low_pfn, unsigned long end_pfn, bool unevictable)
{
- unsigned long low_pfn, end_pfn;
+ unsigned long last_pageblock_nr = 0, pageblock_nr;
+ unsigned long nr_scanned = 0, nr_isolated = 0;
struct list_head *migratelist = &cc->migratepages;
-
- /* Do not scan outside zone boundaries */
- low_pfn = max(cc->migrate_pfn, zone->zone_start_pfn);
-
- /* Only scan within a pageblock boundary */
- end_pfn = ALIGN(low_pfn + pageblock_nr_pages, pageblock_nr_pages);
-
- /* Do not cross the free scanner or scan within a memory hole */
- if (end_pfn > cc->free_pfn || !pfn_valid(low_pfn)) {
- cc->migrate_pfn = end_pfn;
- return 0;
- }
+ isolate_mode_t mode = 0;
+ struct lruvec *lruvec;
+ unsigned long flags;
+ bool locked = false;
+ struct page *page = NULL, *valid_page = NULL;
/*
* Ensure that there are not too many pages isolated from the LRU
* delay for some time until fewer pages are isolated
*/
while (unlikely(too_many_isolated(zone))) {
+ /* async migration should just abort */
+ if (!cc->sync)
+ return 0;
+
congestion_wait(BLK_RW_ASYNC, HZ/10);
if (fatal_signal_pending(current))
}
/* Time to isolate some pages for migration */
- spin_lock_irq(&zone->lru_lock);
+ cond_resched();
for (; low_pfn < end_pfn; low_pfn++) {
- struct page *page;
+ /* give a chance to irqs before checking need_resched() */
+ if (locked && !((low_pfn+1) % SWAP_CLUSTER_MAX)) {
+ if (should_release_lock(&zone->lru_lock)) {
+ spin_unlock_irqrestore(&zone->lru_lock, flags);
+ locked = false;
+ }
+ }
+
+ /*
+ * migrate_pfn does not necessarily start aligned to a
+ * pageblock. Ensure that pfn_valid is called when moving
+ * into a new MAX_ORDER_NR_PAGES range in case of large
+ * memory holes within the zone
+ */
+ if ((low_pfn & (MAX_ORDER_NR_PAGES - 1)) == 0) {
+ if (!pfn_valid(low_pfn)) {
+ low_pfn += MAX_ORDER_NR_PAGES - 1;
+ continue;
+ }
+ }
+
if (!pfn_valid_within(low_pfn))
continue;
+ nr_scanned++;
- /* Get the page and skip if free */
+ /*
+ * Get the page and ensure the page is within the same zone.
+ * See the comment in isolate_freepages about overlapping
+ * nodes. It is deliberate that the new zone lock is not taken
+ * as memory compaction should not move pages between nodes.
+ */
page = pfn_to_page(low_pfn);
+ if (page_zone(page) != zone)
+ continue;
+
+ if (!valid_page)
+ valid_page = page;
+
+ /* If isolation recently failed, do not retry */
+ pageblock_nr = low_pfn >> pageblock_order;
+ if (!isolation_suitable(cc, page))
+ goto next_pageblock;
+
+ /* Skip if free */
if (PageBuddy(page))
continue;
+ /*
+ * For async migration, also only scan in MOVABLE blocks. Async
+ * migration is optimistic to see if the minimum amount of work
+ * satisfies the allocation
+ */
+ if (!cc->sync && last_pageblock_nr != pageblock_nr &&
+ !migrate_async_suitable(get_pageblock_migratetype(page))) {
+ cc->finished_update_migrate = true;
+ goto next_pageblock;
+ }
+
+ /*
+ * Check may be lockless but that's ok as we recheck later.
+ * It's possible to migrate LRU pages and balloon pages
+ * Skip any other type of page
+ */
+ if (!PageLRU(page)) {
+ if (unlikely(balloon_page_movable(page))) {
+ if (locked && balloon_page_isolate(page)) {
+ /* Successfully isolated */
+ cc->finished_update_migrate = true;
+ list_add(&page->lru, migratelist);
+ cc->nr_migratepages++;
+ nr_isolated++;
+ goto check_compact_cluster;
+ }
+ }
+ continue;
+ }
+
+ /*
+ * PageLRU is set. lru_lock normally excludes isolation
+ * splitting and collapsing (collapsing has already happened
+ * if PageLRU is set) but the lock is not necessarily taken
+ * here and it is wasteful to take it just to check transhuge.
+ * Check TransHuge without lock and skip the whole pageblock if
+ * it's either a transhuge or hugetlbfs page, as calling
+ * compound_order() without preventing THP from splitting the
+ * page underneath us may return surprising results.
+ */
+ if (PageTransHuge(page)) {
+ if (!locked)
+ goto next_pageblock;
+ low_pfn += (1 << compound_order(page)) - 1;
+ continue;
+ }
+
+ /* Check if it is ok to still hold the lock */
+ locked = compact_checklock_irqsave(&zone->lru_lock, &flags,
+ locked, cc);
+ if (!locked || fatal_signal_pending(current))
+ break;
+
+ /* Recheck PageLRU and PageTransHuge under lock */
+ if (!PageLRU(page))
+ continue;
+ if (PageTransHuge(page)) {
+ low_pfn += (1 << compound_order(page)) - 1;
+ continue;
+ }
+
+ if (!cc->sync)
+ mode |= ISOLATE_ASYNC_MIGRATE;
+
+ if (unevictable)
+ mode |= ISOLATE_UNEVICTABLE;
+
+ lruvec = mem_cgroup_page_lruvec(page, zone);
+
/* Try isolate the page */
- if (__isolate_lru_page(page, ISOLATE_BOTH, 0) != 0)
+ if (__isolate_lru_page(page, mode) != 0)
continue;
+ VM_BUG_ON(PageTransCompound(page));
+
/* Successfully isolated */
- del_page_from_lru_list(zone, page, page_lru(page));
+ cc->finished_update_migrate = true;
+ del_page_from_lru_list(page, lruvec, page_lru(page));
list_add(&page->lru, migratelist);
- mem_cgroup_del_lru(page);
cc->nr_migratepages++;
+ nr_isolated++;
+check_compact_cluster:
/* Avoid isolating too much */
- if (cc->nr_migratepages == COMPACT_CLUSTER_MAX)
+ if (cc->nr_migratepages == COMPACT_CLUSTER_MAX) {
+ ++low_pfn;
break;
+ }
+
+ continue;
+
+next_pageblock:
+ low_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages) - 1;
+ last_pageblock_nr = pageblock_nr;
}
- acct_isolated(zone, cc);
+ acct_isolated(zone, locked, cc);
- spin_unlock_irq(&zone->lru_lock);
- cc->migrate_pfn = low_pfn;
+ if (locked)
+ spin_unlock_irqrestore(&zone->lru_lock, flags);
+
+ /* Update the pageblock-skip if the whole pageblock was scanned */
+ if (low_pfn == end_pfn)
+ update_pageblock_skip(cc, valid_page, nr_isolated, true);
+
+ trace_mm_compaction_isolate_migratepages(nr_scanned, nr_isolated);
- return cc->nr_migratepages;
+ count_compact_events(COMPACTMIGRATE_SCANNED, nr_scanned);
+ if (nr_isolated)
+ count_compact_events(COMPACTISOLATED, nr_isolated);
+
+ return low_pfn;
+}
+
+#endif /* CONFIG_COMPACTION || CONFIG_CMA */
+#ifdef CONFIG_COMPACTION
+/*
+ * Based on information in the current compact_control, find blocks
+ * suitable for isolating free pages from and then isolate them.
+ */
+static void isolate_freepages(struct zone *zone,
+ struct compact_control *cc)
+{
+ struct page *page;
+ unsigned long high_pfn, low_pfn, pfn, z_end_pfn, end_pfn;
+ int nr_freepages = cc->nr_freepages;
+ struct list_head *freelist = &cc->freepages;
+
+ /*
+ * Initialise the free scanner. The starting point is where we last
+ * scanned from (or the end of the zone if starting). The low point
+ * is the end of the pageblock the migration scanner is using.
+ */
+ pfn = cc->free_pfn;
+ low_pfn = cc->migrate_pfn + pageblock_nr_pages;
+
+ /*
+ * Take care that if the migration scanner is at the end of the zone
+ * that the free scanner does not accidentally move to the next zone
+ * in the next isolation cycle.
+ */
+ high_pfn = min(low_pfn, pfn);
+
+ z_end_pfn = zone_end_pfn(zone);
+
+ /*
+ * Isolate free pages until enough are available to migrate the
+ * pages on cc->migratepages. We stop searching if the migrate
+ * and free page scanners meet or enough free pages are isolated.
+ */
+ for (; pfn > low_pfn && cc->nr_migratepages > nr_freepages;
+ pfn -= pageblock_nr_pages) {
+ unsigned long isolated;
+
+ if (!pfn_valid(pfn))
+ continue;
+
+ /*
+ * Check for overlapping nodes/zones. It's possible on some
+ * configurations to have a setup like
+ * node0 node1 node0
+ * i.e. it's possible that all pages within a zones range of
+ * pages do not belong to a single zone.
+ */
+ page = pfn_to_page(pfn);
+ if (page_zone(page) != zone)
+ continue;
+
+ /* Check the block is suitable for migration */
+ if (!suitable_migration_target(page))
+ continue;
+
+ /* If isolation recently failed, do not retry */
+ if (!isolation_suitable(cc, page))
+ continue;
+
+ /* Found a block suitable for isolating free pages from */
+ isolated = 0;
+
+ /*
+ * As pfn may not start aligned, pfn+pageblock_nr_page
+ * may cross a MAX_ORDER_NR_PAGES boundary and miss
+ * a pfn_valid check. Ensure isolate_freepages_block()
+ * only scans within a pageblock
+ */
+ end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
+ end_pfn = min(end_pfn, z_end_pfn);
+ isolated = isolate_freepages_block(cc, pfn, end_pfn,
+ freelist, false);
+ nr_freepages += isolated;
+
+ /*
+ * Record the highest PFN we isolated pages from. When next
+ * looking for free pages, the search will restart here as
+ * page migration may have returned some pages to the allocator
+ */
+ if (isolated) {
+ cc->finished_update_free = true;
+ high_pfn = max(high_pfn, pfn);
+ }
+ }
+
+ /* split_free_page does not map the pages */
+ map_pages(freelist);
+
+ cc->free_pfn = high_pfn;
+ cc->nr_freepages = nr_freepages;
}
/*
cc->nr_freepages = nr_freepages;
}
+/* possible outcome of isolate_migratepages */
+typedef enum {
+ ISOLATE_ABORT, /* Abort compaction now */
+ ISOLATE_NONE, /* No pages isolated, continue scanning */
+ ISOLATE_SUCCESS, /* Pages isolated, migrate */
+} isolate_migrate_t;
+
+/*
+ * Isolate all pages that can be migrated from the block pointed to by
+ * the migrate scanner within compact_control.
+ */
+static isolate_migrate_t isolate_migratepages(struct zone *zone,
+ struct compact_control *cc)
+{
+ unsigned long low_pfn, end_pfn;
+
+ /* Do not scan outside zone boundaries */
+ low_pfn = max(cc->migrate_pfn, zone->zone_start_pfn);
+
+ /* Only scan within a pageblock boundary */
+ end_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages);
+
+ /* Do not cross the free scanner or scan within a memory hole */
+ if (end_pfn > cc->free_pfn || !pfn_valid(low_pfn)) {
+ cc->migrate_pfn = end_pfn;
+ return ISOLATE_NONE;
+ }
+
+ /* Perform the isolation */
+ low_pfn = isolate_migratepages_range(zone, cc, low_pfn, end_pfn, false);
+ if (!low_pfn || cc->contended)
+ return ISOLATE_ABORT;
+
+ cc->migrate_pfn = low_pfn;
+
+ return ISOLATE_SUCCESS;
+}
+
static int compact_finished(struct zone *zone,
- struct compact_control *cc)
+ struct compact_control *cc)
{
+ unsigned int order;
+ unsigned long watermark;
+
if (fatal_signal_pending(current))
return COMPACT_PARTIAL;
/* Compaction run completes if the migrate and free scanner meet */
- if (cc->free_pfn <= cc->migrate_pfn)
+ if (cc->free_pfn <= cc->migrate_pfn) {
+ /*
+ * Mark that the PG_migrate_skip information should be cleared
+ * by kswapd when it goes to sleep. kswapd does not set the
+ * flag itself as the decision to be clear should be directly
+ * based on an allocation request.
+ */
+ if (!current_is_kswapd())
+ zone->compact_blockskip_flush = true;
+
return COMPACT_COMPLETE;
+ }
+
+ /*
+ * order == -1 is expected when compacting via
+ * /proc/sys/vm/compact_memory
+ */
+ if (cc->order == -1)
+ return COMPACT_CONTINUE;
+
+ /* Compaction run is not finished if the watermark is not met */
+ watermark = low_wmark_pages(zone);
+ watermark += (1 << cc->order);
+
+ if (!zone_watermark_ok(zone, cc->order, watermark, 0, 0))
+ return COMPACT_CONTINUE;
+
+ /* Direct compactor: Is a suitable page free? */
+ for (order = cc->order; order < MAX_ORDER; order++) {
+ struct free_area *area = &zone->free_area[order];
+
+ /* Job done if page is free of the right migratetype */
+ if (!list_empty(&area->free_list[cc->migratetype]))
+ return COMPACT_PARTIAL;
+
+ /* Job done if allocation would set block type */
+ if (cc->order >= pageblock_order && area->nr_free)
+ return COMPACT_PARTIAL;
+ }
+
+ return COMPACT_CONTINUE;
+}
+
+/*
+ * compaction_suitable: Is this suitable to run compaction on this zone now?
+ * Returns
+ * COMPACT_SKIPPED - If there are too few free pages for compaction
+ * COMPACT_PARTIAL - If the allocation would succeed without compaction
+ * COMPACT_CONTINUE - If compaction should run now
+ */
+unsigned long compaction_suitable(struct zone *zone, int order)
+{
+ int fragindex;
+ unsigned long watermark;
+
+ /*
+ * order == -1 is expected when compacting via
+ * /proc/sys/vm/compact_memory
+ */
+ if (order == -1)
+ return COMPACT_CONTINUE;
+
+ /*
+ * Watermarks for order-0 must be met for compaction. Note the 2UL.
+ * This is because during migration, copies of pages need to be
+ * allocated and for a short time, the footprint is higher
+ */
+ watermark = low_wmark_pages(zone) + (2UL << order);
+ if (!zone_watermark_ok(zone, 0, watermark, 0, 0))
+ return COMPACT_SKIPPED;
+
+ /*
+ * fragmentation index determines if allocation failures are due to
+ * low memory or external fragmentation
+ *
+ * index of -1000 implies allocations might succeed depending on
+ * watermarks
+ * index towards 0 implies failure is due to lack of memory
+ * index towards 1000 implies failure is due to fragmentation
+ *
+ * Only compact if a failure would be due to fragmentation.
+ */
+ fragindex = fragmentation_index(zone, order);
+ if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold)
+ return COMPACT_SKIPPED;
+
+ if (fragindex == -1000 && zone_watermark_ok(zone, order, watermark,
+ 0, 0))
+ return COMPACT_PARTIAL;
return COMPACT_CONTINUE;
}
static int compact_zone(struct zone *zone, struct compact_control *cc)
{
int ret;
+ unsigned long start_pfn = zone->zone_start_pfn;
+ unsigned long end_pfn = zone_end_pfn(zone);
+
+ ret = compaction_suitable(zone, cc->order);
+ switch (ret) {
+ case COMPACT_PARTIAL:
+ case COMPACT_SKIPPED:
+ /* Compaction is likely to fail */
+ return ret;
+ case COMPACT_CONTINUE:
+ /* Fall through to compaction */
+ ;
+ }
- /* Setup to move all movable pages to the end of the zone */
- cc->migrate_pfn = zone->zone_start_pfn;
- cc->free_pfn = cc->migrate_pfn + zone->spanned_pages;
- cc->free_pfn &= ~(pageblock_nr_pages-1);
+ /*
+ * Setup to move all movable pages to the end of the zone. Used cached
+ * information on where the scanners should start but check that it
+ * is initialised by ensuring the values are within zone boundaries.
+ */
+ cc->migrate_pfn = zone->compact_cached_migrate_pfn;
+ cc->free_pfn = zone->compact_cached_free_pfn;
+ if (cc->free_pfn < start_pfn || cc->free_pfn > end_pfn) {
+ cc->free_pfn = end_pfn & ~(pageblock_nr_pages-1);
+ zone->compact_cached_free_pfn = cc->free_pfn;
+ }
+ if (cc->migrate_pfn < start_pfn || cc->migrate_pfn > end_pfn) {
+ cc->migrate_pfn = start_pfn;
+ zone->compact_cached_migrate_pfn = cc->migrate_pfn;
+ }
+
+ /*
+ * Clear pageblock skip if there were failures recently and compaction
+ * is about to be retried after being deferred. kswapd does not do
+ * this reset as it'll reset the cached information when going to sleep.
+ */
+ if (compaction_restarting(zone, cc->order) && !current_is_kswapd())
+ __reset_isolation_suitable(zone);
migrate_prep_local();
while ((ret = compact_finished(zone, cc)) == COMPACT_CONTINUE) {
unsigned long nr_migrate, nr_remaining;
+ int err;
- if (!isolate_migratepages(zone, cc))
+ switch (isolate_migratepages(zone, cc)) {
+ case ISOLATE_ABORT:
+ ret = COMPACT_PARTIAL;
+ putback_movable_pages(&cc->migratepages);
+ cc->nr_migratepages = 0;
+ goto out;
+ case ISOLATE_NONE:
continue;
+ case ISOLATE_SUCCESS:
+ ;
+ }
nr_migrate = cc->nr_migratepages;
- migrate_pages(&cc->migratepages, compaction_alloc,
- (unsigned long)cc, 0);
+ err = migrate_pages(&cc->migratepages, compaction_alloc,
+ (unsigned long)cc,
+ cc->sync ? MIGRATE_SYNC_LIGHT : MIGRATE_ASYNC,
+ MR_COMPACTION);
update_nr_listpages(cc);
nr_remaining = cc->nr_migratepages;
- count_vm_event(COMPACTBLOCKS);
- count_vm_events(COMPACTPAGES, nr_migrate - nr_remaining);
- if (nr_remaining)
- count_vm_events(COMPACTPAGEFAILED, nr_remaining);
+ trace_mm_compaction_migratepages(nr_migrate - nr_remaining,
+ nr_remaining);
- /* Release LRU pages not migrated */
- if (!list_empty(&cc->migratepages)) {
- putback_lru_pages(&cc->migratepages);
+ /* Release isolated pages not migrated */
+ if (err) {
+ putback_movable_pages(&cc->migratepages);
cc->nr_migratepages = 0;
+ if (err == -ENOMEM) {
+ ret = COMPACT_PARTIAL;
+ goto out;
+ }
}
-
}
+out:
/* Release free pages and check accounting */
cc->nr_freepages -= release_freepages(&cc->freepages);
VM_BUG_ON(cc->nr_freepages != 0);
return ret;
}
-/* Compact all zones within a node */
-static int compact_node(int nid)
+static unsigned long compact_zone_order(struct zone *zone,
+ int order, gfp_t gfp_mask,
+ bool sync, bool *contended)
{
- int zoneid;
- pg_data_t *pgdat;
+ unsigned long ret;
+ struct compact_control cc = {
+ .nr_freepages = 0,
+ .nr_migratepages = 0,
+ .order = order,
+ .migratetype = allocflags_to_migratetype(gfp_mask),
+ .zone = zone,
+ .sync = sync,
+ };
+ INIT_LIST_HEAD(&cc.freepages);
+ INIT_LIST_HEAD(&cc.migratepages);
+
+ ret = compact_zone(zone, &cc);
+
+ VM_BUG_ON(!list_empty(&cc.freepages));
+ VM_BUG_ON(!list_empty(&cc.migratepages));
+
+ *contended = cc.contended;
+ return ret;
+}
+
+int sysctl_extfrag_threshold = 500;
+
+/**
+ * try_to_compact_pages - Direct compact to satisfy a high-order allocation
+ * @zonelist: The zonelist used for the current allocation
+ * @order: The order of the current allocation
+ * @gfp_mask: The GFP mask of the current allocation
+ * @nodemask: The allowed nodes to allocate from
+ * @sync: Whether migration is synchronous or not
+ * @contended: Return value that is true if compaction was aborted due to lock contention
+ * @page: Optionally capture a free page of the requested order during compaction
+ *
+ * This is the main entry point for direct page compaction.
+ */
+unsigned long try_to_compact_pages(struct zonelist *zonelist,
+ int order, gfp_t gfp_mask, nodemask_t *nodemask,
+ bool sync, bool *contended)
+{
+ enum zone_type high_zoneidx = gfp_zone(gfp_mask);
+ int may_enter_fs = gfp_mask & __GFP_FS;
+ int may_perform_io = gfp_mask & __GFP_IO;
+ struct zoneref *z;
struct zone *zone;
+ int rc = COMPACT_SKIPPED;
+ int alloc_flags = 0;
+
+ /* Check if the GFP flags allow compaction */
+ if (!order || !may_enter_fs || !may_perform_io)
+ return rc;
+
+ count_compact_event(COMPACTSTALL);
+
+#ifdef CONFIG_CMA
+ if (allocflags_to_migratetype(gfp_mask) == MIGRATE_MOVABLE)
+ alloc_flags |= ALLOC_CMA;
+#endif
+ /* Compact each zone in the list */
+ for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx,
+ nodemask) {
+ int status;
+
+ status = compact_zone_order(zone, order, gfp_mask, sync,
+ contended);
+ rc = max(status, rc);
+
+ /* If a normal allocation would succeed, stop compacting */
+ if (zone_watermark_ok(zone, order, low_wmark_pages(zone), 0,
+ alloc_flags))
+ break;
+ }
- if (nid < 0 || nid >= nr_node_ids || !node_online(nid))
- return -EINVAL;
- pgdat = NODE_DATA(nid);
+ return rc;
+}
- /* Flush pending updates to the LRU lists */
- lru_add_drain_all();
+
+/* Compact all zones within a node */
+static void __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
+{
+ int zoneid;
+ struct zone *zone;
for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
- struct compact_control cc = {
- .nr_freepages = 0,
- .nr_migratepages = 0,
- };
zone = &pgdat->node_zones[zoneid];
if (!populated_zone(zone))
continue;
- cc.zone = zone;
- INIT_LIST_HEAD(&cc.freepages);
- INIT_LIST_HEAD(&cc.migratepages);
-
- compact_zone(zone, &cc);
+ cc->nr_freepages = 0;
+ cc->nr_migratepages = 0;
+ cc->zone = zone;
+ INIT_LIST_HEAD(&cc->freepages);
+ INIT_LIST_HEAD(&cc->migratepages);
+
+ if (cc->order == -1 || !compaction_deferred(zone, cc->order))
+ compact_zone(zone, cc);
+
+ if (cc->order > 0) {
+ int ok = zone_watermark_ok(zone, cc->order,
+ low_wmark_pages(zone), 0, 0);
+ if (ok && cc->order >= zone->compact_order_failed)
+ zone->compact_order_failed = cc->order + 1;
+ /* Currently async compaction is never deferred. */
+ else if (!ok && cc->sync)
+ defer_compaction(zone, cc->order);
+ }
- VM_BUG_ON(!list_empty(&cc.freepages));
- VM_BUG_ON(!list_empty(&cc.migratepages));
+ VM_BUG_ON(!list_empty(&cc->freepages));
+ VM_BUG_ON(!list_empty(&cc->migratepages));
}
+}
- return 0;
+void compact_pgdat(pg_data_t *pgdat, int order)
+{
+ struct compact_control cc = {
+ .order = order,
+ .sync = false,
+ };
+
+ __compact_pgdat(pgdat, &cc);
+}
+
+static void compact_node(int nid)
+{
+ struct compact_control cc = {
+ .order = -1,
+ .sync = true,
+ };
+
+ __compact_pgdat(NODE_DATA(nid), &cc);
}
/* Compact all nodes in the system */
-static int compact_nodes(void)
+static void compact_nodes(void)
{
int nid;
+ /* Flush pending updates to the LRU lists */
+ lru_add_drain_all();
+
for_each_online_node(nid)
compact_node(nid);
-
- return COMPACT_COMPLETE;
}
/* The written value is actually unused, all memory is compacted */
void __user *buffer, size_t *length, loff_t *ppos)
{
if (write)
- return compact_nodes();
+ compact_nodes();
+
+ return 0;
+}
+
+int sysctl_extfrag_handler(struct ctl_table *table, int write,
+ void __user *buffer, size_t *length, loff_t *ppos)
+{
+ proc_dointvec_minmax(table, write, buffer, length, ppos);
return 0;
}
+
+#if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
+ssize_t sysfs_compact_node(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ int nid = dev->id;
+
+ if (nid >= 0 && nid < nr_node_ids && node_online(nid)) {
+ /* Flush pending updates to the LRU lists */
+ lru_add_drain_all();
+
+ compact_node(nid);
+ }
+
+ return count;
+}
+static DEVICE_ATTR(compact, S_IWUSR, NULL, sysfs_compact_node);
+
+int compaction_register_node(struct node *node)
+{
+ return device_create_file(&node->dev, &dev_attr_compact);
+}
+
+void compaction_unregister_node(struct node *node)
+{
+ return device_remove_file(&node->dev, &dev_attr_compact);
+}
+#endif /* CONFIG_SYSFS && CONFIG_NUMA */
+
+#endif /* CONFIG_COMPACTION */
Code Review / linux-3.10.git / blobdiff