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Diffstat (limited to 'mm/vmscan.c')
-rw-r--r--mm/vmscan.c281
1 files changed, 221 insertions, 60 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 1be5a6376ef0..a6e65d024995 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -66,17 +66,8 @@ struct scan_control {
int swappiness;
int all_unreclaimable;
-};
-/*
- * The list of shrinker callbacks used by to apply pressure to
- * ageable caches.
- */
-struct shrinker {
- shrinker_t shrinker;
- struct list_head list;
- int seeks; /* seeks to recreate an obj */
- long nr; /* objs pending delete */
+ int order;
};
#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
@@ -121,34 +112,25 @@ static DECLARE_RWSEM(shrinker_rwsem);
/*
* Add a shrinker callback to be called from the vm
*/
-struct shrinker *set_shrinker(int seeks, shrinker_t theshrinker)
+void register_shrinker(struct shrinker *shrinker)
{
- struct shrinker *shrinker;
-
- shrinker = kmalloc(sizeof(*shrinker), GFP_KERNEL);
- if (shrinker) {
- shrinker->shrinker = theshrinker;
- shrinker->seeks = seeks;
- shrinker->nr = 0;
- down_write(&shrinker_rwsem);
- list_add_tail(&shrinker->list, &shrinker_list);
- up_write(&shrinker_rwsem);
- }
- return shrinker;
+ shrinker->nr = 0;
+ down_write(&shrinker_rwsem);
+ list_add_tail(&shrinker->list, &shrinker_list);
+ up_write(&shrinker_rwsem);
}
-EXPORT_SYMBOL(set_shrinker);
+EXPORT_SYMBOL(register_shrinker);
/*
* Remove one
*/
-void remove_shrinker(struct shrinker *shrinker)
+void unregister_shrinker(struct shrinker *shrinker)
{
down_write(&shrinker_rwsem);
list_del(&shrinker->list);
up_write(&shrinker_rwsem);
- kfree(shrinker);
}
-EXPORT_SYMBOL(remove_shrinker);
+EXPORT_SYMBOL(unregister_shrinker);
#define SHRINK_BATCH 128
/*
@@ -185,7 +167,7 @@ unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
list_for_each_entry(shrinker, &shrinker_list, list) {
unsigned long long delta;
unsigned long total_scan;
- unsigned long max_pass = (*shrinker->shrinker)(0, gfp_mask);
+ unsigned long max_pass = (*shrinker->shrink)(0, gfp_mask);
delta = (4 * scanned) / shrinker->seeks;
delta *= max_pass;
@@ -213,8 +195,8 @@ unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
int shrink_ret;
int nr_before;
- nr_before = (*shrinker->shrinker)(0, gfp_mask);
- shrink_ret = (*shrinker->shrinker)(this_scan, gfp_mask);
+ nr_before = (*shrinker->shrink)(0, gfp_mask);
+ shrink_ret = (*shrinker->shrink)(this_scan, gfp_mask);
if (shrink_ret == -1)
break;
if (shrink_ret < nr_before)
@@ -289,6 +271,12 @@ static void handle_write_error(struct address_space *mapping,
unlock_page(page);
}
+/* Request for sync pageout. */
+enum pageout_io {
+ PAGEOUT_IO_ASYNC,
+ PAGEOUT_IO_SYNC,
+};
+
/* possible outcome of pageout() */
typedef enum {
/* failed to write page out, page is locked */
@@ -305,7 +293,8 @@ typedef enum {
* pageout is called by shrink_page_list() for each dirty page.
* Calls ->writepage().
*/
-static pageout_t pageout(struct page *page, struct address_space *mapping)
+static pageout_t pageout(struct page *page, struct address_space *mapping,
+ enum pageout_io sync_writeback)
{
/*
* If the page is dirty, only perform writeback if that write
@@ -364,6 +353,15 @@ static pageout_t pageout(struct page *page, struct address_space *mapping)
ClearPageReclaim(page);
return PAGE_ACTIVATE;
}
+
+ /*
+ * Wait on writeback if requested to. This happens when
+ * direct reclaiming a large contiguous area and the
+ * first attempt to free a range of pages fails.
+ */
+ if (PageWriteback(page) && sync_writeback == PAGEOUT_IO_SYNC)
+ wait_on_page_writeback(page);
+
if (!PageWriteback(page)) {
/* synchronous write or broken a_ops? */
ClearPageReclaim(page);
@@ -441,7 +439,8 @@ cannot_free:
* shrink_page_list() returns the number of reclaimed pages
*/
static unsigned long shrink_page_list(struct list_head *page_list,
- struct scan_control *sc)
+ struct scan_control *sc,
+ enum pageout_io sync_writeback)
{
LIST_HEAD(ret_pages);
struct pagevec freed_pvec;
@@ -476,12 +475,28 @@ static unsigned long shrink_page_list(struct list_head *page_list,
if (page_mapped(page) || PageSwapCache(page))
sc->nr_scanned++;
- if (PageWriteback(page))
- goto keep_locked;
+ may_enter_fs = (sc->gfp_mask & __GFP_FS) ||
+ (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
+
+ if (PageWriteback(page)) {
+ /*
+ * Synchronous reclaim is performed in two passes,
+ * first an asynchronous pass over the list to
+ * start parallel writeback, and a second synchronous
+ * pass to wait for the IO to complete. Wait here
+ * for any page for which writeback has already
+ * started.
+ */
+ if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs)
+ wait_on_page_writeback(page);
+ else
+ goto keep_locked;
+ }
referenced = page_referenced(page, 1);
/* In active use or really unfreeable? Activate it. */
- if (referenced && page_mapping_inuse(page))
+ if (sc->order <= PAGE_ALLOC_COSTLY_ORDER &&
+ referenced && page_mapping_inuse(page))
goto activate_locked;
#ifdef CONFIG_SWAP
@@ -495,8 +510,6 @@ static unsigned long shrink_page_list(struct list_head *page_list,
#endif /* CONFIG_SWAP */
mapping = page_mapping(page);
- may_enter_fs = (sc->gfp_mask & __GFP_FS) ||
- (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
/*
* The page is mapped into the page tables of one or more
@@ -514,7 +527,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
}
if (PageDirty(page)) {
- if (referenced)
+ if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && referenced)
goto keep_locked;
if (!may_enter_fs)
goto keep_locked;
@@ -522,7 +535,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
goto keep_locked;
/* Page is dirty, try to write it out here */
- switch(pageout(page, mapping)) {
+ switch (pageout(page, mapping, sync_writeback)) {
case PAGE_KEEP:
goto keep_locked;
case PAGE_ACTIVATE:
@@ -598,6 +611,51 @@ keep:
return nr_reclaimed;
}
+/* LRU Isolation modes. */
+#define ISOLATE_INACTIVE 0 /* Isolate inactive pages. */
+#define ISOLATE_ACTIVE 1 /* Isolate active pages. */
+#define ISOLATE_BOTH 2 /* Isolate both active and inactive pages. */
+
+/*
+ * Attempt to remove the specified page from its LRU. Only take this page
+ * if it is of the appropriate PageActive status. Pages which are being
+ * freed elsewhere are also ignored.
+ *
+ * page: page to consider
+ * mode: one of the LRU isolation modes defined above
+ *
+ * returns 0 on success, -ve errno on failure.
+ */
+static int __isolate_lru_page(struct page *page, int mode)
+{
+ int ret = -EINVAL;
+
+ /* Only take pages on the LRU. */
+ if (!PageLRU(page))
+ return ret;
+
+ /*
+ * When checking the active state, we need to be sure we are
+ * dealing with comparible boolean values. Take the logical not
+ * of each.
+ */
+ if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode))
+ return ret;
+
+ ret = -EBUSY;
+ if (likely(get_page_unless_zero(page))) {
+ /*
+ * Be careful not to clear PageLRU until after we're
+ * sure the page is not being freed elsewhere -- the
+ * page release code relies on it.
+ */
+ ClearPageLRU(page);
+ ret = 0;
+ }
+
+ return ret;
+}
+
/*
* zone->lru_lock is heavily contended. Some of the functions that
* shrink the lists perform better by taking out a batch of pages
@@ -612,38 +670,90 @@ keep:
* @src: The LRU list to pull pages off.
* @dst: The temp list to put pages on to.
* @scanned: The number of pages that were scanned.
+ * @order: The caller's attempted allocation order
+ * @mode: One of the LRU isolation modes
*
* 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)
+ unsigned long *scanned, int order, int mode)
{
unsigned long nr_taken = 0;
- struct page *page;
unsigned long scan;
for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) {
- struct list_head *target;
+ struct page *page;
+ unsigned long pfn;
+ unsigned long end_pfn;
+ unsigned long page_pfn;
+ int zone_id;
+
page = lru_to_page(src);
prefetchw_prev_lru_page(page, src, flags);
VM_BUG_ON(!PageLRU(page));
- list_del(&page->lru);
- target = src;
- if (likely(get_page_unless_zero(page))) {
- /*
- * Be careful not to clear PageLRU until after we're
- * sure the page is not being freed elsewhere -- the
- * page release code relies on it.
- */
- ClearPageLRU(page);
- target = dst;
+ switch (__isolate_lru_page(page, mode)) {
+ case 0:
+ list_move(&page->lru, dst);
nr_taken++;
- } /* else it is being freed elsewhere */
+ break;
+
+ case -EBUSY:
+ /* else it is being freed elsewhere */
+ list_move(&page->lru, src);
+ continue;
+
+ default:
+ BUG();
+ }
+
+ if (!order)
+ continue;
+
+ /*
+ * Attempt to take all pages in the order aligned region
+ * surrounding the tag page. Only take those pages of
+ * the same active state as that tag page. We may safely
+ * round the target page pfn down to the requested order
+ * as the mem_map is guarenteed valid out to MAX_ORDER,
+ * where that page is in a different zone we will detect
+ * it from its zone id and abort this block scan.
+ */
+ zone_id = page_zone_id(page);
+ page_pfn = page_to_pfn(page);
+ pfn = page_pfn & ~((1 << order) - 1);
+ end_pfn = pfn + (1 << order);
+ for (; pfn < end_pfn; pfn++) {
+ struct page *cursor_page;
+
+ /* The target page is in the block, ignore it. */
+ if (unlikely(pfn == page_pfn))
+ continue;
- list_add(&page->lru, target);
+ /* Avoid holes within the zone. */
+ if (unlikely(!pfn_valid_within(pfn)))
+ break;
+
+ cursor_page = pfn_to_page(pfn);
+ /* Check that we have not crossed a zone boundary. */
+ if (unlikely(page_zone_id(cursor_page) != zone_id))
+ continue;
+ switch (__isolate_lru_page(cursor_page, mode)) {
+ case 0:
+ list_move(&cursor_page->lru, dst);
+ nr_taken++;
+ scan++;
+ break;
+
+ case -EBUSY:
+ /* else it is being freed elsewhere */
+ list_move(&cursor_page->lru, src);
+ default:
+ break;
+ }
+ }
}
*scanned = scan;
@@ -651,6 +761,24 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
}
/*
+ * 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)
+{
+ int nr_active = 0;
+ struct page *page;
+
+ list_for_each_entry(page, page_list, lru)
+ if (PageActive(page)) {
+ ClearPageActive(page);
+ nr_active++;
+ }
+
+ return nr_active;
+}
+
+/*
* shrink_inactive_list() is a helper for shrink_zone(). It returns the number
* of reclaimed pages
*/
@@ -671,16 +799,46 @@ static unsigned long shrink_inactive_list(unsigned long max_scan,
unsigned long nr_taken;
unsigned long nr_scan;
unsigned long nr_freed;
+ unsigned long nr_active;
nr_taken = isolate_lru_pages(sc->swap_cluster_max,
- &zone->inactive_list,
- &page_list, &nr_scan);
- __mod_zone_page_state(zone, NR_INACTIVE, -nr_taken);
+ &zone->inactive_list,
+ &page_list, &nr_scan, sc->order,
+ (sc->order > PAGE_ALLOC_COSTLY_ORDER)?
+ ISOLATE_BOTH : ISOLATE_INACTIVE);
+ nr_active = clear_active_flags(&page_list);
+ __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));
zone->pages_scanned += nr_scan;
spin_unlock_irq(&zone->lru_lock);
nr_scanned += nr_scan;
- nr_freed = shrink_page_list(&page_list, sc);
+ nr_freed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC);
+
+ /*
+ * If we are direct reclaiming for contiguous pages and we do
+ * not reclaim everything in the list, try again and wait
+ * for IO to complete. This will stall high-order allocations
+ * but that should be acceptable to the caller
+ */
+ if (nr_freed < nr_taken && !current_is_kswapd() &&
+ sc->order > PAGE_ALLOC_COSTLY_ORDER) {
+ congestion_wait(WRITE, HZ/10);
+
+ /*
+ * The attempt at page out may have made some
+ * of the pages active, mark them inactive again.
+ */
+ nr_active = clear_active_flags(&page_list);
+ count_vm_events(PGDEACTIVATE, nr_active);
+
+ nr_freed += shrink_page_list(&page_list, sc,
+ PAGEOUT_IO_SYNC);
+ }
+
nr_reclaimed += nr_freed;
local_irq_disable();
if (current_is_kswapd()) {
@@ -820,7 +978,7 @@ force_reclaim_mapped:
lru_add_drain();
spin_lock_irq(&zone->lru_lock);
pgmoved = isolate_lru_pages(nr_pages, &zone->active_list,
- &l_hold, &pgscanned);
+ &l_hold, &pgscanned, sc->order, ISOLATE_ACTIVE);
zone->pages_scanned += pgscanned;
__mod_zone_page_state(zone, NR_ACTIVE, -pgmoved);
spin_unlock_irq(&zone->lru_lock);
@@ -1011,7 +1169,7 @@ static unsigned long shrink_zones(int priority, struct zone **zones,
* holds filesystem locks which prevent writeout this might not work, and the
* allocation attempt will fail.
*/
-unsigned long try_to_free_pages(struct zone **zones, gfp_t gfp_mask)
+unsigned long try_to_free_pages(struct zone **zones, int order, gfp_t gfp_mask)
{
int priority;
int ret = 0;
@@ -1026,6 +1184,7 @@ unsigned long try_to_free_pages(struct zone **zones, gfp_t gfp_mask)
.swap_cluster_max = SWAP_CLUSTER_MAX,
.may_swap = 1,
.swappiness = vm_swappiness,
+ .order = order,
};
count_vm_event(ALLOCSTALL);
@@ -1131,6 +1290,7 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order)
.may_swap = 1,
.swap_cluster_max = SWAP_CLUSTER_MAX,
.swappiness = vm_swappiness,
+ .order = order,
};
/*
* temp_priority is used to remember the scanning priority at which
@@ -1314,6 +1474,7 @@ static int kswapd(void *p)
* trying to free the first piece of memory in the first place).
*/
tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
+ set_freezable();
order = 0;
for ( ; ; ) {
generated by cgit v1.2.3 (git 2.0.4) at 2024-05-23 08:48:34 +0000