* Multiqueue VM started 5.8.00, Rik van Riel.
*/
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/gfp.h>
#include <linux/sysctl.h>
#include <linux/oom.h>
#include <linux/prefetch.h>
+#include <linux/printk.h>
#include <asm/tlbflush.h>
#include <asm/div64.h>
#include <linux/swapops.h>
+#include <linux/balloon_compaction.h>
#include "internal.h"
#include <trace/events/vmscan.h>
struct scan_control {
- /* Incremented by the number of inactive pages that were scanned */
- unsigned long nr_scanned;
-
- /* Number of pages freed so far during a call to shrink_zones() */
- unsigned long nr_reclaimed;
-
/* How many pages shrink_list() should reclaim */
unsigned long nr_to_reclaim;
- unsigned long hibernation_mode;
-
/* This context's GFP mask */
gfp_t gfp_mask;
- int may_writepage;
-
- /* Can mapped pages be reclaimed? */
- int may_unmap;
-
- /* Can pages be swapped as part of reclaim? */
- int may_swap;
-
+ /* Allocation order */
int order;
- /* Scan (total_size >> priority) pages at once */
- int priority;
+ /*
+ * Nodemask of nodes allowed by the caller. If NULL, all nodes
+ * are scanned.
+ */
+ nodemask_t *nodemask;
/*
* The memory cgroup that hit its limit and as a result is the
*/
struct mem_cgroup *target_mem_cgroup;
- /*
- * Nodemask of nodes allowed by the caller. If NULL, all nodes
- * are scanned.
- */
- nodemask_t *nodemask;
+ /* Scan (total_size >> priority) pages at once */
+ int priority;
+
+ unsigned int may_writepage:1;
+
+ /* Can mapped pages be reclaimed? */
+ unsigned int may_unmap:1;
+
+ /* Can pages be swapped as part of reclaim? */
+ unsigned int may_swap:1;
+
+ /* Can cgroups be reclaimed below their normal consumption range? */
+ unsigned int may_thrash:1;
+
+ unsigned int hibernation_mode:1;
+
+ /* One of the zones is ready for compaction */
+ unsigned int compaction_ready:1;
+
+ /* Incremented by the number of inactive pages that were scanned */
+ unsigned long nr_scanned;
+
+ /* Number of pages freed so far during a call to shrink_zones() */
+ unsigned long nr_reclaimed;
};
#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
* From 0 .. 100. Higher means more swappy.
*/
int vm_swappiness = 60;
-unsigned long vm_total_pages; /* The total number of pages which the VM controls */
+/*
+ * The total number of pages which are beyond the high watermark within all
+ * zones.
+ */
+unsigned long vm_total_pages;
static LIST_HEAD(shrinker_list);
static DECLARE_RWSEM(shrinker_rwsem);
{
return !sc->target_mem_cgroup;
}
+
+/**
+ * sane_reclaim - is the usual dirty throttling mechanism operational?
+ * @sc: scan_control in question
+ *
+ * The normal page dirty throttling mechanism in balance_dirty_pages() is
+ * completely broken with the legacy memcg and direct stalling in
+ * shrink_page_list() is used for throttling instead, which lacks all the
+ * niceties such as fairness, adaptive pausing, bandwidth proportional
+ * allocation and configurability.
+ *
+ * This function tests whether the vmscan currently in progress can assume
+ * that the normal dirty throttling mechanism is operational.
+ */
+static bool sane_reclaim(struct scan_control *sc)
+{
+ struct mem_cgroup *memcg = sc->target_mem_cgroup;
+
+ if (!memcg)
+ return true;
+#ifdef CONFIG_CGROUP_WRITEBACK
+ if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
+ return true;
+#endif
+ return false;
+}
#else
static bool global_reclaim(struct scan_control *sc)
{
return true;
}
+
+static bool sane_reclaim(struct scan_control *sc)
+{
+ return true;
+}
#endif
+static unsigned long zone_reclaimable_pages(struct zone *zone)
+{
+ unsigned long nr;
+
+ nr = zone_page_state(zone, NR_ACTIVE_FILE) +
+ zone_page_state(zone, NR_INACTIVE_FILE);
+
+ if (get_nr_swap_pages() > 0)
+ nr += zone_page_state(zone, NR_ACTIVE_ANON) +
+ zone_page_state(zone, NR_INACTIVE_ANON);
+
+ return nr;
+}
+
+bool zone_reclaimable(struct zone *zone)
+{
+ return zone_page_state(zone, NR_PAGES_SCANNED) <
+ zone_reclaimable_pages(zone) * 6;
+}
+
static unsigned long get_lru_size(struct lruvec *lruvec, enum lru_list lru)
{
if (!mem_cgroup_disabled())
}
/*
- * Add a shrinker callback to be called from the vm
+ * Add a shrinker callback to be called from the vm.
*/
-void register_shrinker(struct shrinker *shrinker)
+int register_shrinker(struct shrinker *shrinker)
{
- atomic_long_set(&shrinker->nr_in_batch, 0);
+ size_t size = sizeof(*shrinker->nr_deferred);
+
+ /*
+ * If we only have one possible node in the system anyway, save
+ * ourselves the trouble and disable NUMA aware behavior. This way we
+ * will save memory and some small loop time later.
+ */
+ if (nr_node_ids == 1)
+ shrinker->flags &= ~SHRINKER_NUMA_AWARE;
+
+ if (shrinker->flags & SHRINKER_NUMA_AWARE)
+ size *= nr_node_ids;
+
+ shrinker->nr_deferred = kzalloc(size, GFP_KERNEL);
+ if (!shrinker->nr_deferred)
+ return -ENOMEM;
+
down_write(&shrinker_rwsem);
list_add_tail(&shrinker->list, &shrinker_list);
up_write(&shrinker_rwsem);
+ return 0;
}
EXPORT_SYMBOL(register_shrinker);
down_write(&shrinker_rwsem);
list_del(&shrinker->list);
up_write(&shrinker_rwsem);
+ kfree(shrinker->nr_deferred);
}
EXPORT_SYMBOL(unregister_shrinker);
-static inline int do_shrinker_shrink(struct shrinker *shrinker,
- struct shrink_control *sc,
- unsigned long nr_to_scan)
-{
- sc->nr_to_scan = nr_to_scan;
- return (*shrinker->shrink)(shrinker, sc);
+#define SHRINK_BATCH 128
+
+static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
+ struct shrinker *shrinker,
+ unsigned long nr_scanned,
+ unsigned long nr_eligible)
+{
+ unsigned long freed = 0;
+ unsigned long long delta;
+ long total_scan;
+ long freeable;
+ long nr;
+ long new_nr;
+ int nid = shrinkctl->nid;
+ long batch_size = shrinker->batch ? shrinker->batch
+ : SHRINK_BATCH;
+ long scanned = 0, next_deferred;
+
+ freeable = shrinker->count_objects(shrinker, shrinkctl);
+ if (freeable == 0)
+ return 0;
+
+ /*
+ * copy the current shrinker scan count into a local variable
+ * and zero it so that other concurrent shrinker invocations
+ * don't also do this scanning work.
+ */
+ nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0);
+
+ total_scan = nr;
+ delta = (4 * nr_scanned) / shrinker->seeks;
+ delta *= freeable;
+ do_div(delta, nr_eligible + 1);
+ total_scan += delta;
+ if (total_scan < 0) {
+ pr_err("shrink_slab: %pF negative objects to delete nr=%ld\n",
+ shrinker->scan_objects, total_scan);
+ total_scan = freeable;
+ next_deferred = nr;
+ } else
+ next_deferred = total_scan;
+
+ /*
+ * We need to avoid excessive windup on filesystem shrinkers
+ * due to large numbers of GFP_NOFS allocations causing the
+ * shrinkers to return -1 all the time. This results in a large
+ * nr being built up so when a shrink that can do some work
+ * comes along it empties the entire cache due to nr >>>
+ * freeable. This is bad for sustaining a working set in
+ * memory.
+ *
+ * Hence only allow the shrinker to scan the entire cache when
+ * a large delta change is calculated directly.
+ */
+ if (delta < freeable / 4)
+ total_scan = min(total_scan, freeable / 2);
+
+ /*
+ * Avoid risking looping forever due to too large nr value:
+ * never try to free more than twice the estimate number of
+ * freeable entries.
+ */
+ if (total_scan > freeable * 2)
+ total_scan = freeable * 2;
+
+ trace_mm_shrink_slab_start(shrinker, shrinkctl, nr,
+ nr_scanned, nr_eligible,
+ freeable, delta, total_scan);
+
+ /*
+ * Normally, we should not scan less than batch_size objects in one
+ * pass to avoid too frequent shrinker calls, but if the slab has less
+ * than batch_size objects in total and we are really tight on memory,
+ * we will try to reclaim all available objects, otherwise we can end
+ * up failing allocations although there are plenty of reclaimable
+ * objects spread over several slabs with usage less than the
+ * batch_size.
+ *
+ * We detect the "tight on memory" situations by looking at the total
+ * number of objects we want to scan (total_scan). If it is greater
+ * than the total number of objects on slab (freeable), we must be
+ * scanning at high prio and therefore should try to reclaim as much as
+ * possible.
+ */
+ while (total_scan >= batch_size ||
+ total_scan >= freeable) {
+ unsigned long ret;
+ unsigned long nr_to_scan = min(batch_size, total_scan);
+
+ shrinkctl->nr_to_scan = nr_to_scan;
+ ret = shrinker->scan_objects(shrinker, shrinkctl);
+ if (ret == SHRINK_STOP)
+ break;
+ freed += ret;
+
+ count_vm_events(SLABS_SCANNED, nr_to_scan);
+ total_scan -= nr_to_scan;
+ scanned += nr_to_scan;
+
+ cond_resched();
+ }
+
+ if (next_deferred >= scanned)
+ next_deferred -= scanned;
+ else
+ next_deferred = 0;
+ /*
+ * move the unused scan count back into the shrinker in a
+ * manner that handles concurrent updates. If we exhausted the
+ * scan, there is no need to do an update.
+ */
+ if (next_deferred > 0)
+ new_nr = atomic_long_add_return(next_deferred,
+ &shrinker->nr_deferred[nid]);
+ else
+ new_nr = atomic_long_read(&shrinker->nr_deferred[nid]);
+
+ trace_mm_shrink_slab_end(shrinker, nid, freed, nr, new_nr, total_scan);
+ return freed;
}
-#define SHRINK_BATCH 128
-/*
- * Call the shrink functions to age shrinkable caches
+/**
+ * shrink_slab - shrink slab caches
+ * @gfp_mask: allocation context
+ * @nid: node whose slab caches to target
+ * @memcg: memory cgroup whose slab caches to target
+ * @nr_scanned: pressure numerator
+ * @nr_eligible: pressure denominator
*
- * Here we assume it costs one seek to replace a lru page and that it also
- * takes a seek to recreate a cache object. With this in mind we age equal
- * percentages of the lru and ageable caches. This should balance the seeks
- * generated by these structures.
+ * Call the shrink functions to age shrinkable caches.
*
- * If the vm encountered mapped pages on the LRU it increase the pressure on
- * slab to avoid swapping.
+ * @nid is passed along to shrinkers with SHRINKER_NUMA_AWARE set,
+ * unaware shrinkers will receive a node id of 0 instead.
*
- * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits.
+ * @memcg specifies the memory cgroup to target. If it is not NULL,
+ * only shrinkers with SHRINKER_MEMCG_AWARE set will be called to scan
+ * objects from the memory cgroup specified. Otherwise all shrinkers
+ * are called, and memcg aware shrinkers are supposed to scan the
+ * global list then.
*
- * `lru_pages' represents the number of on-LRU pages in all the zones which
- * are eligible for the caller's allocation attempt. It is used for balancing
- * slab reclaim versus page reclaim.
+ * @nr_scanned and @nr_eligible form a ratio that indicate how much of
+ * the available objects should be scanned. Page reclaim for example
+ * passes the number of pages scanned and the number of pages on the
+ * LRU lists that it considered on @nid, plus a bias in @nr_scanned
+ * when it encountered mapped pages. The ratio is further biased by
+ * the ->seeks setting of the shrink function, which indicates the
+ * cost to recreate an object relative to that of an LRU page.
*
- * Returns the number of slab objects which we shrunk.
+ * Returns the number of reclaimed slab objects.
*/
-unsigned long shrink_slab(struct shrink_control *shrink,
- unsigned long nr_pages_scanned,
- unsigned long lru_pages)
+static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
+ struct mem_cgroup *memcg,
+ unsigned long nr_scanned,
+ unsigned long nr_eligible)
{
struct shrinker *shrinker;
- unsigned long ret = 0;
+ unsigned long freed = 0;
+
+ if (memcg && !memcg_kmem_is_active(memcg))
+ return 0;
- if (nr_pages_scanned == 0)
- nr_pages_scanned = SWAP_CLUSTER_MAX;
+ if (nr_scanned == 0)
+ nr_scanned = SWAP_CLUSTER_MAX;
if (!down_read_trylock(&shrinker_rwsem)) {
- /* Assume we'll be able to shrink next time */
- ret = 1;
+ /*
+ * If we would return 0, our callers would understand that we
+ * have nothing else to shrink and give up trying. By returning
+ * 1 we keep it going and assume we'll be able to shrink next
+ * time.
+ */
+ freed = 1;
goto out;
}
list_for_each_entry(shrinker, &shrinker_list, list) {
- unsigned long long delta;
- long total_scan;
- long max_pass;
- int shrink_ret = 0;
- long nr;
- long new_nr;
- long batch_size = shrinker->batch ? shrinker->batch
- : SHRINK_BATCH;
-
- max_pass = do_shrinker_shrink(shrinker, shrink, 0);
- if (max_pass <= 0)
- continue;
+ struct shrink_control sc = {
+ .gfp_mask = gfp_mask,
+ .nid = nid,
+ .memcg = memcg,
+ };
- /*
- * copy the current shrinker scan count into a local variable
- * and zero it so that other concurrent shrinker invocations
- * don't also do this scanning work.
- */
- nr = atomic_long_xchg(&shrinker->nr_in_batch, 0);
-
- total_scan = nr;
- delta = (4 * nr_pages_scanned) / shrinker->seeks;
- delta *= max_pass;
- do_div(delta, lru_pages + 1);
- total_scan += delta;
- if (total_scan < 0) {
- printk(KERN_ERR "shrink_slab: %pF negative objects to "
- "delete nr=%ld\n",
- shrinker->shrink, total_scan);
- total_scan = max_pass;
- }
+ if (memcg && !(shrinker->flags & SHRINKER_MEMCG_AWARE))
+ continue;
- /*
- * We need to avoid excessive windup on filesystem shrinkers
- * due to large numbers of GFP_NOFS allocations causing the
- * shrinkers to return -1 all the time. This results in a large
- * nr being built up so when a shrink that can do some work
- * comes along it empties the entire cache due to nr >>>
- * max_pass. This is bad for sustaining a working set in
- * memory.
- *
- * Hence only allow the shrinker to scan the entire cache when
- * a large delta change is calculated directly.
- */
- if (delta < max_pass / 4)
- total_scan = min(total_scan, max_pass / 2);
+ if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
+ sc.nid = 0;
- /*
- * Avoid risking looping forever due to too large nr value:
- * never try to free more than twice the estimate number of
- * freeable entries.
- */
- if (total_scan > max_pass * 2)
- total_scan = max_pass * 2;
+ freed += do_shrink_slab(&sc, shrinker, nr_scanned, nr_eligible);
+ }
- trace_mm_shrink_slab_start(shrinker, shrink, nr,
- nr_pages_scanned, lru_pages,
- max_pass, delta, total_scan);
+ up_read(&shrinker_rwsem);
+out:
+ cond_resched();
+ return freed;
+}
- while (total_scan >= batch_size) {
- int nr_before;
+void drop_slab_node(int nid)
+{
+ unsigned long freed;
- nr_before = do_shrinker_shrink(shrinker, shrink, 0);
- shrink_ret = do_shrinker_shrink(shrinker, shrink,
- batch_size);
- if (shrink_ret == -1)
- break;
- if (shrink_ret < nr_before)
- ret += nr_before - shrink_ret;
- count_vm_events(SLABS_SCANNED, batch_size);
- total_scan -= batch_size;
+ do {
+ struct mem_cgroup *memcg = NULL;
- cond_resched();
- }
+ freed = 0;
+ do {
+ freed += shrink_slab(GFP_KERNEL, nid, memcg,
+ 1000, 1000);
+ } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
+ } while (freed > 10);
+}
- /*
- * move the unused scan count back into the shrinker in a
- * manner that handles concurrent updates. If we exhausted the
- * scan, there is no need to do an update.
- */
- if (total_scan > 0)
- new_nr = atomic_long_add_return(total_scan,
- &shrinker->nr_in_batch);
- else
- new_nr = atomic_long_read(&shrinker->nr_in_batch);
+void drop_slab(void)
+{
+ int nid;
- trace_mm_shrink_slab_end(shrinker, shrink_ret, nr, new_nr);
- }
- up_read(&shrinker_rwsem);
-out:
- cond_resched();
- return ret;
+ for_each_online_node(nid)
+ drop_slab_node(nid);
}
static inline int is_page_cache_freeable(struct page *page)
return page_count(page) - page_has_private(page) == 2;
}
-static int may_write_to_queue(struct backing_dev_info *bdi,
- struct scan_control *sc)
+static int may_write_to_inode(struct inode *inode, struct scan_control *sc)
{
if (current->flags & PF_SWAPWRITE)
return 1;
- if (!bdi_write_congested(bdi))
+ if (!inode_write_congested(inode))
return 1;
- if (bdi == current->backing_dev_info)
+ if (inode_to_bdi(inode) == current->backing_dev_info)
return 1;
return 0;
}
* stalls if we need to run get_block(). We could test
* PagePrivate for that.
*
- * If this process is currently in __generic_file_aio_write() against
+ * If this process is currently in __generic_file_write_iter() against
* this page's queue, we can perform writeback even if that
* will block.
*
if (page_has_private(page)) {
if (try_to_free_buffers(page)) {
ClearPageDirty(page);
- printk("%s: orphaned page\n", __func__);
+ pr_info("%s: orphaned page\n", __func__);
return PAGE_CLEAN;
}
}
}
if (mapping->a_ops->writepage == NULL)
return PAGE_ACTIVATE;
- if (!may_write_to_queue(mapping->backing_dev_info, sc))
+ if (!may_write_to_inode(mapping->host, sc))
return PAGE_KEEP;
if (clear_page_dirty_for_io(page)) {
* Same as remove_mapping, but if the page is removed from the mapping, it
* gets returned with a refcount of 0.
*/
-static int __remove_mapping(struct address_space *mapping, struct page *page)
+static int __remove_mapping(struct address_space *mapping, struct page *page,
+ bool reclaimed)
{
+ unsigned long flags;
+ struct mem_cgroup *memcg;
+
BUG_ON(!PageLocked(page));
BUG_ON(mapping != page_mapping(page));
- spin_lock_irq(&mapping->tree_lock);
+ memcg = mem_cgroup_begin_page_stat(page);
+ spin_lock_irqsave(&mapping->tree_lock, flags);
/*
* The non racy check for a busy page.
*
if (PageSwapCache(page)) {
swp_entry_t swap = { .val = page_private(page) };
+ mem_cgroup_swapout(page, swap);
__delete_from_swap_cache(page);
- spin_unlock_irq(&mapping->tree_lock);
- swapcache_free(swap, page);
+ spin_unlock_irqrestore(&mapping->tree_lock, flags);
+ mem_cgroup_end_page_stat(memcg);
+ swapcache_free(swap);
} else {
void (*freepage)(struct page *);
+ void *shadow = NULL;
freepage = mapping->a_ops->freepage;
-
- __delete_from_page_cache(page);
- spin_unlock_irq(&mapping->tree_lock);
- mem_cgroup_uncharge_cache_page(page);
+ /*
+ * Remember a shadow entry for reclaimed file cache in
+ * order to detect refaults, thus thrashing, later on.
+ *
+ * But don't store shadows in an address space that is
+ * already exiting. This is not just an optizimation,
+ * inode reclaim needs to empty out the radix tree or
+ * the nodes are lost. Don't plant shadows behind its
+ * back.
+ */
+ if (reclaimed && page_is_file_cache(page) &&
+ !mapping_exiting(mapping))
+ shadow = workingset_eviction(mapping, page);
+ __delete_from_page_cache(page, shadow, memcg);
+ spin_unlock_irqrestore(&mapping->tree_lock, flags);
+ mem_cgroup_end_page_stat(memcg);
if (freepage != NULL)
freepage(page);
return 1;
cannot_free:
- spin_unlock_irq(&mapping->tree_lock);
+ spin_unlock_irqrestore(&mapping->tree_lock, flags);
+ mem_cgroup_end_page_stat(memcg);
return 0;
}
*/
int remove_mapping(struct address_space *mapping, struct page *page)
{
- if (__remove_mapping(mapping, page)) {
+ if (__remove_mapping(mapping, page, false)) {
/*
* Unfreezing the refcount with 1 rather than 2 effectively
* drops the pagecache ref for us without requiring another
*/
void putback_lru_page(struct page *page)
{
- int lru;
- int active = !!TestClearPageActive(page);
+ bool is_unevictable;
int was_unevictable = PageUnevictable(page);
- VM_BUG_ON(PageLRU(page));
+ VM_BUG_ON_PAGE(PageLRU(page), page);
redo:
ClearPageUnevictable(page);
* unevictable page on [in]active list.
* We know how to handle that.
*/
- lru = active + page_lru_base_type(page);
- lru_cache_add_lru(page, lru);
+ is_unevictable = false;
+ lru_cache_add(page);
} else {
/*
* Put unevictable pages directly on zone's unevictable
* list.
*/
- lru = LRU_UNEVICTABLE;
+ is_unevictable = true;
add_page_to_unevictable_list(page);
/*
* When racing with an mlock or AS_UNEVICTABLE clearing
* 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)) {
+ if (is_unevictable && page_evictable(page)) {
if (!isolate_lru_page(page)) {
put_page(page);
goto redo;
*/
}
- if (was_unevictable && lru != LRU_UNEVICTABLE)
+ if (was_unevictable && !is_unevictable)
count_vm_event(UNEVICTABLE_PGRESCUED);
- else if (!was_unevictable && lru == LRU_UNEVICTABLE)
+ else if (!was_unevictable && is_unevictable)
count_vm_event(UNEVICTABLE_PGCULLED);
put_page(page); /* drop ref from isolate */
return PAGEREF_RECLAIM;
}
+/* Check if a page is dirty or under writeback */
+static void page_check_dirty_writeback(struct page *page,
+ bool *dirty, bool *writeback)
+{
+ struct address_space *mapping;
+
+ /*
+ * Anonymous pages are not handled by flushers and must be written
+ * from reclaim context. Do not stall reclaim based on them
+ */
+ if (!page_is_file_cache(page)) {
+ *dirty = false;
+ *writeback = false;
+ return;
+ }
+
+ /* By default assume that the page flags are accurate */
+ *dirty = PageDirty(page);
+ *writeback = PageWriteback(page);
+
+ /* Verify dirty/writeback state if the filesystem supports it */
+ if (!page_has_private(page))
+ return;
+
+ mapping = page_mapping(page);
+ if (mapping && mapping->a_ops->is_dirty_writeback)
+ mapping->a_ops->is_dirty_writeback(page, dirty, writeback);
+}
+
/*
* shrink_page_list() returns the number of reclaimed pages
*/
struct scan_control *sc,
enum ttu_flags ttu_flags,
unsigned long *ret_nr_dirty,
+ unsigned long *ret_nr_unqueued_dirty,
+ unsigned long *ret_nr_congested,
unsigned long *ret_nr_writeback,
+ unsigned long *ret_nr_immediate,
bool force_reclaim)
{
LIST_HEAD(ret_pages);
LIST_HEAD(free_pages);
int pgactivate = 0;
+ unsigned long nr_unqueued_dirty = 0;
unsigned long nr_dirty = 0;
unsigned long nr_congested = 0;
unsigned long nr_reclaimed = 0;
unsigned long nr_writeback = 0;
+ unsigned long nr_immediate = 0;
cond_resched();
- mem_cgroup_uncharge_start();
while (!list_empty(page_list)) {
struct address_space *mapping;
struct page *page;
int may_enter_fs;
enum page_references references = PAGEREF_RECLAIM_CLEAN;
+ bool dirty, writeback;
cond_resched();
if (!trylock_page(page))
goto keep;
- VM_BUG_ON(PageActive(page));
- VM_BUG_ON(page_zone(page) != zone);
+ VM_BUG_ON_PAGE(PageActive(page), page);
+ VM_BUG_ON_PAGE(page_zone(page) != zone, page);
sc->nr_scanned++;
may_enter_fs = (sc->gfp_mask & __GFP_FS) ||
(PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
+ /*
+ * The number of dirty pages determines if a zone is marked
+ * reclaim_congested which affects wait_iff_congested. kswapd
+ * will stall and start writing pages if the tail of the LRU
+ * is all dirty unqueued pages.
+ */
+ page_check_dirty_writeback(page, &dirty, &writeback);
+ if (dirty || writeback)
+ nr_dirty++;
+
+ if (dirty && !writeback)
+ nr_unqueued_dirty++;
+
+ /*
+ * Treat this page as congested if the underlying BDI is or if
+ * pages are cycling through the LRU so quickly that the
+ * pages marked for immediate reclaim are making it to the
+ * end of the LRU a second time.
+ */
+ mapping = page_mapping(page);
+ if (((dirty || writeback) && mapping &&
+ inode_write_congested(mapping->host)) ||
+ (writeback && PageReclaim(page)))
+ nr_congested++;
+
+ /*
+ * If a page at the tail of the LRU is under writeback, there
+ * are three cases to consider.
+ *
+ * 1) If reclaim is encountering an excessive number of pages
+ * under writeback and this page is both under writeback and
+ * PageReclaim then it indicates that pages are being queued
+ * for IO but are being recycled through the LRU before the
+ * IO can complete. Waiting on the page itself risks an
+ * indefinite stall if it is impossible to writeback the
+ * page due to IO error or disconnected storage so instead
+ * note that the LRU is being scanned too quickly and the
+ * caller can stall after page list has been processed.
+ *
+ * 2) Global or new memcg reclaim encounters a page that is
+ * not marked for immediate reclaim, or the caller does not
+ * have __GFP_FS (or __GFP_IO if it's simply going to swap,
+ * not to fs). In this case mark the page for immediate
+ * reclaim and continue scanning.
+ *
+ * Require may_enter_fs because we would wait on fs, which
+ * may not have submitted IO yet. And the loop driver might
+ * enter reclaim, and deadlock if it waits on a page for
+ * which it is needed to do the write (loop masks off
+ * __GFP_IO|__GFP_FS for this reason); but more thought
+ * would probably show more reasons.
+ *
+ * 3) Legacy memcg encounters a page that is already marked
+ * PageReclaim. memcg does not have any dirty pages
+ * throttling so we could easily OOM just because too many
+ * pages are in writeback and there is nothing else to
+ * reclaim. Wait for the writeback to complete.
+ */
if (PageWriteback(page)) {
- /*
- * memcg doesn't have any dirty pages throttling so we
- * could easily OOM just because too many pages are in
- * writeback and there is nothing else to reclaim.
- *
- * Check __GFP_IO, certainly because a loop driver
- * thread might enter reclaim, and deadlock if it waits
- * on a page for which it is needed to do the write
- * (loop masks off __GFP_IO|__GFP_FS for this reason);
- * but more thought would probably show more reasons.
- *
- * Don't require __GFP_FS, since we're not going into
- * the FS, just waiting on its writeback completion.
- * Worryingly, ext4 gfs2 and xfs allocate pages with
- * grab_cache_page_write_begin(,,AOP_FLAG_NOFS), so
- * testing may_enter_fs here is liable to OOM on them.
- */
- if (global_reclaim(sc) ||
- !PageReclaim(page) || !(sc->gfp_mask & __GFP_IO)) {
+ /* Case 1 above */
+ if (current_is_kswapd() &&
+ PageReclaim(page) &&
+ test_bit(ZONE_WRITEBACK, &zone->flags)) {
+ nr_immediate++;
+ goto keep_locked;
+
+ /* Case 2 above */
+ } else if (sane_reclaim(sc) ||
+ !PageReclaim(page) || !may_enter_fs) {
/*
* This is slightly racy - end_page_writeback()
* might have just cleared PageReclaim, then
SetPageReclaim(page);
nr_writeback++;
goto keep_locked;
+
+ /* Case 3 above */
+ } else {
+ unlock_page(page);
+ wait_on_page_writeback(page);
+ /* then go back and try same page again */
+ list_add_tail(&page->lru, page_list);
+ continue;
}
- wait_on_page_writeback(page);
}
if (!force_reclaim)
if (!add_to_swap(page, page_list))
goto activate_locked;
may_enter_fs = 1;
- }
- mapping = page_mapping(page);
+ /* Adding to swap updated mapping */
+ mapping = page_mapping(page);
+ }
/*
* The page is mapped into the page tables of one or more
* processes. Try to unmap it here.
*/
if (page_mapped(page) && mapping) {
- switch (try_to_unmap(page, ttu_flags)) {
+ switch (try_to_unmap(page,
+ ttu_flags|TTU_BATCH_FLUSH)) {
case SWAP_FAIL:
goto activate_locked;
case SWAP_AGAIN:
}
if (PageDirty(page)) {
- nr_dirty++;
-
/*
* Only kswapd can writeback filesystem pages to
- * avoid risk of stack overflow but do not writeback
- * unless under significant pressure.
+ * avoid risk of stack overflow but only writeback
+ * if many dirty pages have been encountered.
*/
if (page_is_file_cache(page) &&
(!current_is_kswapd() ||
- sc->priority >= DEF_PRIORITY - 2)) {
+ !test_bit(ZONE_DIRTY, &zone->flags))) {
/*
* Immediately reclaim when written back.
* Similar in principal to deactivate_page()
if (!sc->may_writepage)
goto keep_locked;
- /* Page is dirty, try to write it out here */
+ /*
+ * Page is dirty. Flush the TLB if a writable entry
+ * potentially exists to avoid CPU writes after IO
+ * starts and then write it out here.
+ */
+ try_to_unmap_flush_dirty();
switch (pageout(page, mapping, sc)) {
case PAGE_KEEP:
- nr_congested++;
goto keep_locked;
case PAGE_ACTIVATE:
goto activate_locked;
}
}
- if (!mapping || !__remove_mapping(mapping, page))
+ if (!mapping || !__remove_mapping(mapping, page, true))
goto keep_locked;
/*
if (PageSwapCache(page))
try_to_free_swap(page);
unlock_page(page);
- putback_lru_page(page);
+ list_add(&page->lru, &ret_pages);
continue;
activate_locked:
/* Not a candidate for swapping, so reclaim swap space. */
if (PageSwapCache(page) && vm_swap_full())
try_to_free_swap(page);
- VM_BUG_ON(PageActive(page));
+ VM_BUG_ON_PAGE(PageActive(page), page);
SetPageActive(page);
pgactivate++;
keep_locked:
unlock_page(page);
keep:
list_add(&page->lru, &ret_pages);
- VM_BUG_ON(PageLRU(page) || PageUnevictable(page));
+ VM_BUG_ON_PAGE(PageLRU(page) || PageUnevictable(page), page);
}
- /*
- * Tag a zone as congested if all the dirty pages encountered were
- * backed by a congested BDI. In this case, reclaimers should just
- * back off and wait for congestion to clear because further reclaim
- * will encounter the same problem
- */
- if (nr_dirty && nr_dirty == nr_congested && global_reclaim(sc))
- zone_set_flag(zone, ZONE_CONGESTED);
-
- free_hot_cold_page_list(&free_pages, 1);
+ mem_cgroup_uncharge_list(&free_pages);
+ try_to_unmap_flush();
+ free_hot_cold_page_list(&free_pages, true);
list_splice(&ret_pages, page_list);
count_vm_events(PGACTIVATE, pgactivate);
- mem_cgroup_uncharge_end();
+
*ret_nr_dirty += nr_dirty;
+ *ret_nr_congested += nr_congested;
+ *ret_nr_unqueued_dirty += nr_unqueued_dirty;
*ret_nr_writeback += nr_writeback;
+ *ret_nr_immediate += nr_immediate;
return nr_reclaimed;
}
.priority = DEF_PRIORITY,
.may_unmap = 1,
};
- unsigned long ret, dummy1, dummy2;
+ unsigned long ret, dummy1, dummy2, dummy3, dummy4, dummy5;
struct page *page, *next;
LIST_HEAD(clean_pages);
list_for_each_entry_safe(page, next, page_list, lru) {
- if (page_is_file_cache(page) && !PageDirty(page)) {
+ if (page_is_file_cache(page) && !PageDirty(page) &&
+ !isolated_balloon_page(page)) {
ClearPageActive(page);
list_move(&page->lru, &clean_pages);
}
}
ret = shrink_page_list(&clean_pages, zone, &sc,
- TTU_UNMAP|TTU_IGNORE_ACCESS,
- &dummy1, &dummy2, true);
+ TTU_UNMAP|TTU_IGNORE_ACCESS,
+ &dummy1, &dummy2, &dummy3, &dummy4, &dummy5, true);
list_splice(&clean_pages, page_list);
- __mod_zone_page_state(zone, NR_ISOLATED_FILE, -ret);
+ mod_zone_page_state(zone, NR_ISOLATED_FILE, -ret);
return ret;
}
unsigned long nr_taken = 0;
unsigned long scan;
- for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) {
+ for (scan = 0; scan < nr_to_scan && nr_taken < nr_to_scan &&
+ !list_empty(src); scan++) {
struct page *page;
int nr_pages;
page = lru_to_page(src);
prefetchw_prev_lru_page(page, src, flags);
- VM_BUG_ON(!PageLRU(page));
+ VM_BUG_ON_PAGE(!PageLRU(page), page);
switch (__isolate_lru_page(page, mode)) {
case 0:
{
int ret = -EBUSY;
- VM_BUG_ON(!page_count(page));
+ VM_BUG_ON_PAGE(!page_count(page), page);
if (PageLRU(page)) {
struct zone *zone = page_zone(page);
if (current_is_kswapd())
return 0;
- if (!global_reclaim(sc))
+ if (!sane_reclaim(sc))
return 0;
if (file) {
* won't get blocked by normal direct-reclaimers, forming a circular
* deadlock.
*/
- if ((sc->gfp_mask & GFP_IOFS) == GFP_IOFS)
+ if ((sc->gfp_mask & (__GFP_IO | __GFP_FS)) == (__GFP_IO | __GFP_FS))
inactive >>= 3;
return isolated > inactive;
struct page *page = lru_to_page(page_list);
int lru;
- VM_BUG_ON(PageLRU(page));
+ VM_BUG_ON_PAGE(PageLRU(page), page);
list_del(&page->lru);
if (unlikely(!page_evictable(page))) {
spin_unlock_irq(&zone->lru_lock);
if (unlikely(PageCompound(page))) {
spin_unlock_irq(&zone->lru_lock);
+ mem_cgroup_uncharge(page);
(*get_compound_page_dtor(page))(page);
spin_lock_irq(&zone->lru_lock);
} else
list_splice(&pages_to_free, page_list);
}
+/*
+ * If a kernel thread (such as nfsd for loop-back mounts) services
+ * a backing device by writing to the page cache it sets PF_LESS_THROTTLE.
+ * In that case we should only throttle if the backing device it is
+ * writing to is congested. In other cases it is safe to throttle.
+ */
+static int current_may_throttle(void)
+{
+ return !(current->flags & PF_LESS_THROTTLE) ||
+ current->backing_dev_info == NULL ||
+ bdi_write_congested(current->backing_dev_info);
+}
+
/*
* shrink_inactive_list() is a helper for shrink_zone(). It returns the number
* of reclaimed pages
unsigned long nr_reclaimed = 0;
unsigned long nr_taken;
unsigned long nr_dirty = 0;
+ unsigned long nr_congested = 0;
+ unsigned long nr_unqueued_dirty = 0;
unsigned long nr_writeback = 0;
+ unsigned long nr_immediate = 0;
isolate_mode_t isolate_mode = 0;
int file = is_file_lru(lru);
struct zone *zone = lruvec_zone(lruvec);
__mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken);
if (global_reclaim(sc)) {
- zone->pages_scanned += nr_scanned;
+ __mod_zone_page_state(zone, NR_PAGES_SCANNED, nr_scanned);
if (current_is_kswapd())
__count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scanned);
else
return 0;
nr_reclaimed = shrink_page_list(&page_list, zone, sc, TTU_UNMAP,
- &nr_dirty, &nr_writeback, false);
+ &nr_dirty, &nr_unqueued_dirty, &nr_congested,
+ &nr_writeback, &nr_immediate,
+ false);
spin_lock_irq(&zone->lru_lock);
spin_unlock_irq(&zone->lru_lock);
- free_hot_cold_page_list(&page_list, 1);
+ mem_cgroup_uncharge_list(&page_list);
+ free_hot_cold_page_list(&page_list, true);
/*
* If reclaim is isolating dirty pages under writeback, it implies
* as there is no guarantee the dirtying process is throttled in the
* same way balance_dirty_pages() manages.
*
- * This scales the number of dirty pages that must be under writeback
- * before throttling depending on priority. It is a simple backoff
- * function that has the most effect in the range DEF_PRIORITY to
- * DEF_PRIORITY-2 which is the priority reclaim is considered to be
- * in trouble and reclaim is considered to be in trouble.
- *
- * DEF_PRIORITY 100% isolated pages must be PageWriteback to throttle
- * DEF_PRIORITY-1 50% must be PageWriteback
- * DEF_PRIORITY-2 25% must be PageWriteback, kswapd in trouble
- * ...
- * DEF_PRIORITY-6 For SWAP_CLUSTER_MAX isolated pages, throttle if any
- * isolated page is PageWriteback
+ * Once a zone is flagged ZONE_WRITEBACK, kswapd will count the number
+ * of pages under pages flagged for immediate reclaim and stall if any
+ * are encountered in the nr_immediate check below.
+ */
+ if (nr_writeback && nr_writeback == nr_taken)
+ set_bit(ZONE_WRITEBACK, &zone->flags);
+
+ /*
+ * Legacy memcg will stall in page writeback so avoid forcibly
+ * stalling here.
+ */
+ if (sane_reclaim(sc)) {
+ /*
+ * Tag a zone as congested if all the dirty pages scanned were
+ * backed by a congested BDI and wait_iff_congested will stall.
+ */
+ if (nr_dirty && nr_dirty == nr_congested)
+ set_bit(ZONE_CONGESTED, &zone->flags);
+
+ /*
+ * If dirty pages are scanned that are not queued for IO, it
+ * implies that flushers are not keeping up. In this case, flag
+ * the zone ZONE_DIRTY and kswapd will start writing pages from
+ * reclaim context.
+ */
+ if (nr_unqueued_dirty == nr_taken)
+ set_bit(ZONE_DIRTY, &zone->flags);
+
+ /*
+ * If kswapd scans pages marked marked for immediate
+ * reclaim and under writeback (nr_immediate), it implies
+ * that pages are cycling through the LRU faster than
+ * they are written so also forcibly stall.
+ */
+ if (nr_immediate && current_may_throttle())
+ congestion_wait(BLK_RW_ASYNC, HZ/10);
+ }
+
+ /*
+ * Stall direct reclaim for IO completions if underlying BDIs or zone
+ * is congested. Allow kswapd to continue until it starts encountering
+ * unqueued dirty pages or cycling through the LRU too quickly.
*/
- if (nr_writeback && nr_writeback >=
- (nr_taken >> (DEF_PRIORITY - sc->priority)))
+ if (!sc->hibernation_mode && !current_is_kswapd() &&
+ current_may_throttle())
wait_iff_congested(zone, BLK_RW_ASYNC, HZ/10);
trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id,
page = lru_to_page(list);
lruvec = mem_cgroup_page_lruvec(page, zone);
- VM_BUG_ON(PageLRU(page));
+ VM_BUG_ON_PAGE(PageLRU(page), page);
SetPageLRU(page);
nr_pages = hpage_nr_pages(page);
if (unlikely(PageCompound(page))) {
spin_unlock_irq(&zone->lru_lock);
+ mem_cgroup_uncharge(page);
(*get_compound_page_dtor(page))(page);
spin_lock_irq(&zone->lru_lock);
} else
nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &l_hold,
&nr_scanned, sc, isolate_mode, lru);
if (global_reclaim(sc))
- zone->pages_scanned += nr_scanned;
+ __mod_zone_page_state(zone, NR_PAGES_SCANNED, nr_scanned);
reclaim_stat->recent_scanned[file] += nr_taken;
* Count referenced pages from currently used mappings as rotated,
* even though only some of them are actually re-activated. This
* helps balance scan pressure between file and anonymous pages in
- * get_scan_ratio.
+ * get_scan_count.
*/
reclaim_stat->recent_rotated[file] += nr_rotated;
__mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken);
spin_unlock_irq(&zone->lru_lock);
- free_hot_cold_page_list(&l_hold, 1);
+ mem_cgroup_uncharge_list(&l_hold);
+ free_hot_cold_page_list(&l_hold, true);
}
#ifdef CONFIG_SWAP
-static int inactive_anon_is_low_global(struct zone *zone)
+static bool inactive_anon_is_low_global(struct zone *zone)
{
unsigned long active, inactive;
active = zone_page_state(zone, NR_ACTIVE_ANON);
inactive = zone_page_state(zone, NR_INACTIVE_ANON);
- if (inactive * zone->inactive_ratio < active)
- return 1;
-
- return 0;
+ return inactive * zone->inactive_ratio < active;
}
/**
* Returns true if the zone does not have enough inactive anon pages,
* meaning some active anon pages need to be deactivated.
*/
-static int inactive_anon_is_low(struct lruvec *lruvec)
+static bool inactive_anon_is_low(struct lruvec *lruvec)
{
/*
* If we don't have swap space, anonymous page deactivation
* is pointless.
*/
if (!total_swap_pages)
- return 0;
+ return false;
if (!mem_cgroup_disabled())
return mem_cgroup_inactive_anon_is_low(lruvec);
return inactive_anon_is_low_global(lruvec_zone(lruvec));
}
#else
-static inline int inactive_anon_is_low(struct lruvec *lruvec)
+static inline bool inactive_anon_is_low(struct lruvec *lruvec)
{
- return 0;
+ return false;
}
#endif
* This uses a different ratio than the anonymous pages, because
* the page cache uses a use-once replacement algorithm.
*/
-static int inactive_file_is_low(struct lruvec *lruvec)
+static bool inactive_file_is_low(struct lruvec *lruvec)
{
unsigned long inactive;
unsigned long active;
return active > inactive;
}
-static int inactive_list_is_low(struct lruvec *lruvec, enum lru_list lru)
+static bool inactive_list_is_low(struct lruvec *lruvec, enum lru_list lru)
{
if (is_file_lru(lru))
return inactive_file_is_low(lruvec);
return shrink_inactive_list(nr_to_scan, lruvec, sc, lru);
}
-static int vmscan_swappiness(struct scan_control *sc)
-{
- if (global_reclaim(sc))
- return vm_swappiness;
- return mem_cgroup_swappiness(sc->target_mem_cgroup);
-}
-
enum scan_balance {
SCAN_EQUAL,
SCAN_FRACT,
* nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan
* nr[2] = file inactive pages to scan; nr[3] = file active pages to scan
*/
-static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
- unsigned long *nr)
+static void get_scan_count(struct lruvec *lruvec, int swappiness,
+ struct scan_control *sc, unsigned long *nr,
+ unsigned long *lru_pages)
{
struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
u64 fraction[2];
struct zone *zone = lruvec_zone(lruvec);
unsigned long anon_prio, file_prio;
enum scan_balance scan_balance;
- unsigned long anon, file, free;
+ unsigned long anon, file;
bool force_scan = false;
unsigned long ap, fp;
enum lru_list lru;
+ bool some_scanned;
+ int pass;
/*
* If the zone or memcg is small, nr[l] can be 0. This
* latencies, so it's better to scan a minimum amount there as
* well.
*/
- if (current_is_kswapd() && zone->all_unreclaimable)
- force_scan = true;
+ if (current_is_kswapd()) {
+ if (!zone_reclaimable(zone))
+ force_scan = true;
+ if (!mem_cgroup_lruvec_online(lruvec))
+ force_scan = true;
+ }
if (!global_reclaim(sc))
force_scan = true;
* using the memory controller's swap limit feature would be
* too expensive.
*/
- if (!global_reclaim(sc) && !vmscan_swappiness(sc)) {
+ if (!global_reclaim(sc) && !swappiness) {
scan_balance = SCAN_FILE;
goto out;
}
* system is close to OOM, scan both anon and file equally
* (unless the swappiness setting disagrees with swapping).
*/
- if (!sc->priority && vmscan_swappiness(sc)) {
+ if (!sc->priority && swappiness) {
scan_balance = SCAN_EQUAL;
goto out;
}
- anon = get_lru_size(lruvec, LRU_ACTIVE_ANON) +
- get_lru_size(lruvec, LRU_INACTIVE_ANON);
- file = get_lru_size(lruvec, LRU_ACTIVE_FILE) +
- get_lru_size(lruvec, LRU_INACTIVE_FILE);
-
/*
- * If it's foreseeable that reclaiming the file cache won't be
- * enough to get the zone back into a desirable shape, we have
- * to swap. Better start now and leave the - probably heavily
- * thrashing - remaining file pages alone.
+ * Prevent the reclaimer from falling into the cache trap: as
+ * cache pages start out inactive, every cache fault will tip
+ * the scan balance towards the file LRU. And as the file LRU
+ * shrinks, so does the window for rotation from references.
+ * This means we have a runaway feedback loop where a tiny
+ * thrashing file LRU becomes infinitely more attractive than
+ * anon pages. Try to detect this based on file LRU size.
*/
if (global_reclaim(sc)) {
- free = zone_page_state(zone, NR_FREE_PAGES);
- if (unlikely(file + free <= high_wmark_pages(zone))) {
+ unsigned long zonefile;
+ unsigned long zonefree;
+
+ zonefree = zone_page_state(zone, NR_FREE_PAGES);
+ zonefile = zone_page_state(zone, NR_ACTIVE_FILE) +
+ zone_page_state(zone, NR_INACTIVE_FILE);
+
+ if (unlikely(zonefile + zonefree <= high_wmark_pages(zone))) {
scan_balance = SCAN_ANON;
goto out;
}
* With swappiness at 100, anonymous and file have the same priority.
* This scanning priority is essentially the inverse of IO cost.
*/
- anon_prio = vmscan_swappiness(sc);
+ anon_prio = swappiness;
file_prio = 200 - anon_prio;
/*
*
* anon in [0], file in [1]
*/
+
+ anon = get_lru_size(lruvec, LRU_ACTIVE_ANON) +
+ get_lru_size(lruvec, LRU_INACTIVE_ANON);
+ file = get_lru_size(lruvec, LRU_ACTIVE_FILE) +
+ get_lru_size(lruvec, LRU_INACTIVE_FILE);
+
spin_lock_irq(&zone->lru_lock);
if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) {
reclaim_stat->recent_scanned[0] /= 2;
fraction[1] = fp;
denominator = ap + fp + 1;
out:
- for_each_evictable_lru(lru) {
- int file = is_file_lru(lru);
- unsigned long size;
- unsigned long scan;
-
- size = get_lru_size(lruvec, lru);
- scan = size >> sc->priority;
+ some_scanned = false;
+ /* Only use force_scan on second pass. */
+ for (pass = 0; !some_scanned && pass < 2; pass++) {
+ *lru_pages = 0;
+ for_each_evictable_lru(lru) {
+ int file = is_file_lru(lru);
+ unsigned long size;
+ unsigned long scan;
- if (!scan && force_scan)
- scan = min(size, SWAP_CLUSTER_MAX);
+ size = get_lru_size(lruvec, lru);
+ scan = size >> sc->priority;
+
+ if (!scan && pass && force_scan)
+ scan = min(size, SWAP_CLUSTER_MAX);
+
+ switch (scan_balance) {
+ case SCAN_EQUAL:
+ /* Scan lists relative to size */
+ break;
+ case SCAN_FRACT:
+ /*
+ * Scan types proportional to swappiness and
+ * their relative recent reclaim efficiency.
+ */
+ scan = div64_u64(scan * fraction[file],
+ denominator);
+ break;
+ case SCAN_FILE:
+ case SCAN_ANON:
+ /* Scan one type exclusively */
+ if ((scan_balance == SCAN_FILE) != file) {
+ size = 0;
+ scan = 0;
+ }
+ break;
+ default:
+ /* Look ma, no brain */
+ BUG();
+ }
+
+ *lru_pages += size;
+ nr[lru] = scan;
- switch (scan_balance) {
- case SCAN_EQUAL:
- /* Scan lists relative to size */
- break;
- case SCAN_FRACT:
/*
- * Scan types proportional to swappiness and
- * their relative recent reclaim efficiency.
+ * Skip the second pass and don't force_scan,
+ * if we found something to scan.
*/
- scan = div64_u64(scan * fraction[file], denominator);
- break;
- case SCAN_FILE:
- case SCAN_ANON:
- /* Scan one type exclusively */
- if ((scan_balance == SCAN_FILE) != file)
- scan = 0;
- break;
- default:
- /* Look ma, no brain */
- BUG();
+ some_scanned |= !!scan;
}
- nr[lru] = scan;
}
}
/*
* This is a basic per-zone page freer. Used by both kswapd and direct reclaim.
*/
-static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
+static void shrink_lruvec(struct lruvec *lruvec, int swappiness,
+ struct scan_control *sc, unsigned long *lru_pages)
{
unsigned long nr[NR_LRU_LISTS];
+ unsigned long targets[NR_LRU_LISTS];
unsigned long nr_to_scan;
enum lru_list lru;
unsigned long nr_reclaimed = 0;
unsigned long nr_to_reclaim = sc->nr_to_reclaim;
struct blk_plug plug;
+ bool scan_adjusted;
+
+ get_scan_count(lruvec, swappiness, sc, nr, lru_pages);
+
+ /* Record the original scan target for proportional adjustments later */
+ memcpy(targets, nr, sizeof(nr));
- get_scan_count(lruvec, sc, nr);
+ /*
+ * Global reclaiming within direct reclaim at DEF_PRIORITY is a normal
+ * event that can occur when there is little memory pressure e.g.
+ * multiple streaming readers/writers. Hence, we do not abort scanning
+ * when the requested number of pages are reclaimed when scanning at
+ * DEF_PRIORITY on the assumption that the fact we are direct
+ * reclaiming implies that kswapd is not keeping up and it is best to
+ * do a batch of work at once. For memcg reclaim one check is made to
+ * abort proportional reclaim if either the file or anon lru has already
+ * dropped to zero at the first pass.
+ */
+ scan_adjusted = (global_reclaim(sc) && !current_is_kswapd() &&
+ sc->priority == DEF_PRIORITY);
blk_start_plug(&plug);
while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
nr[LRU_INACTIVE_FILE]) {
+ unsigned long nr_anon, nr_file, percentage;
+ unsigned long nr_scanned;
+
for_each_evictable_lru(lru) {
if (nr[lru]) {
nr_to_scan = min(nr[lru], SWAP_CLUSTER_MAX);
lruvec, sc);
}
}
+
+ if (nr_reclaimed < nr_to_reclaim || scan_adjusted)
+ continue;
+
+ /*
+ * For kswapd and memcg, reclaim at least the number of pages
+ * requested. Ensure that the anon and file LRUs are scanned
+ * proportionally what was requested by get_scan_count(). We
+ * stop reclaiming one LRU and reduce the amount scanning
+ * proportional to the original scan target.
+ */
+ nr_file = nr[LRU_INACTIVE_FILE] + nr[LRU_ACTIVE_FILE];
+ nr_anon = nr[LRU_INACTIVE_ANON] + nr[LRU_ACTIVE_ANON];
+
/*
- * On large memory systems, scan >> priority can become
- * really large. This is fine for the starting priority;
- * we want to put equal scanning pressure on each zone.
- * However, if the VM has a harder time of freeing pages,
- * with multiple processes reclaiming pages, the total
- * freeing target can get unreasonably large.
+ * It's just vindictive to attack the larger once the smaller
+ * has gone to zero. And given the way we stop scanning the
+ * smaller below, this makes sure that we only make one nudge
+ * towards proportionality once we've got nr_to_reclaim.
*/
- if (nr_reclaimed >= nr_to_reclaim &&
- sc->priority < DEF_PRIORITY)
+ if (!nr_file || !nr_anon)
break;
+
+ if (nr_file > nr_anon) {
+ unsigned long scan_target = targets[LRU_INACTIVE_ANON] +
+ targets[LRU_ACTIVE_ANON] + 1;
+ lru = LRU_BASE;
+ percentage = nr_anon * 100 / scan_target;
+ } else {
+ unsigned long scan_target = targets[LRU_INACTIVE_FILE] +
+ targets[LRU_ACTIVE_FILE] + 1;
+ lru = LRU_FILE;
+ percentage = nr_file * 100 / scan_target;
+ }
+
+ /* Stop scanning the smaller of the LRU */
+ nr[lru] = 0;
+ nr[lru + LRU_ACTIVE] = 0;
+
+ /*
+ * Recalculate the other LRU scan count based on its original
+ * scan target and the percentage scanning already complete
+ */
+ lru = (lru == LRU_FILE) ? LRU_BASE : LRU_FILE;
+ nr_scanned = targets[lru] - nr[lru];
+ nr[lru] = targets[lru] * (100 - percentage) / 100;
+ nr[lru] -= min(nr[lru], nr_scanned);
+
+ lru += LRU_ACTIVE;
+ nr_scanned = targets[lru] - nr[lru];
+ nr[lru] = targets[lru] * (100 - percentage) / 100;
+ nr[lru] -= min(nr[lru], nr_scanned);
+
+ scan_adjusted = true;
}
blk_finish_plug(&plug);
sc->nr_reclaimed += nr_reclaimed;
return true;
/* If compaction would go ahead or the allocation would succeed, stop */
- switch (compaction_suitable(zone, sc->order)) {
+ switch (compaction_suitable(zone, sc->order, 0, 0)) {
case COMPACT_PARTIAL:
case COMPACT_CONTINUE:
return false;
}
}
-static void shrink_zone(struct zone *zone, struct scan_control *sc)
+static bool shrink_zone(struct zone *zone, struct scan_control *sc,
+ bool is_classzone)
{
+ struct reclaim_state *reclaim_state = current->reclaim_state;
unsigned long nr_reclaimed, nr_scanned;
+ bool reclaimable = false;
do {
struct mem_cgroup *root = sc->target_mem_cgroup;
.zone = zone,
.priority = sc->priority,
};
+ unsigned long zone_lru_pages = 0;
struct mem_cgroup *memcg;
nr_reclaimed = sc->nr_reclaimed;
memcg = mem_cgroup_iter(root, NULL, &reclaim);
do {
+ unsigned long lru_pages;
+ unsigned long scanned;
struct lruvec *lruvec;
+ int swappiness;
+
+ if (mem_cgroup_low(root, memcg)) {
+ if (!sc->may_thrash)
+ continue;
+ mem_cgroup_events(memcg, MEMCG_LOW, 1);
+ }
lruvec = mem_cgroup_zone_lruvec(zone, memcg);
+ swappiness = mem_cgroup_swappiness(memcg);
+ scanned = sc->nr_scanned;
- shrink_lruvec(lruvec, sc);
+ shrink_lruvec(lruvec, swappiness, sc, &lru_pages);
+ zone_lru_pages += lru_pages;
+
+ if (memcg && is_classzone)
+ shrink_slab(sc->gfp_mask, zone_to_nid(zone),
+ memcg, sc->nr_scanned - scanned,
+ lru_pages);
/*
* Direct reclaim and kswapd have to scan all memory
mem_cgroup_iter_break(root, memcg);
break;
}
- memcg = mem_cgroup_iter(root, memcg, &reclaim);
- } while (memcg);
+ } while ((memcg = mem_cgroup_iter(root, memcg, &reclaim)));
+
+ /*
+ * Shrink the slab caches in the same proportion that
+ * the eligible LRU pages were scanned.
+ */
+ if (global_reclaim(sc) && is_classzone)
+ shrink_slab(sc->gfp_mask, zone_to_nid(zone), NULL,
+ sc->nr_scanned - nr_scanned,
+ zone_lru_pages);
+
+ if (reclaim_state) {
+ sc->nr_reclaimed += reclaim_state->reclaimed_slab;
+ reclaim_state->reclaimed_slab = 0;
+ }
vmpressure(sc->gfp_mask, sc->target_mem_cgroup,
sc->nr_scanned - nr_scanned,
sc->nr_reclaimed - nr_reclaimed);
+ if (sc->nr_reclaimed - nr_reclaimed)
+ reclaimable = true;
+
} while (should_continue_reclaim(zone, sc->nr_reclaimed - nr_reclaimed,
sc->nr_scanned - nr_scanned, sc));
+
+ return reclaimable;
}
-/* Returns true if compaction should go ahead for a high-order request */
-static inline bool compaction_ready(struct zone *zone, struct scan_control *sc)
+/*
+ * Returns true if compaction should go ahead for a high-order request, or
+ * the high-order allocation would succeed without compaction.
+ */
+static inline bool compaction_ready(struct zone *zone, int order)
{
unsigned long balance_gap, watermark;
bool watermark_ok;
- /* Do not consider compaction for orders reclaim is meant to satisfy */
- if (sc->order <= PAGE_ALLOC_COSTLY_ORDER)
- return false;
-
/*
* Compaction takes time to run and there are potentially other
* callers using the pages just freed. Continue reclaiming until
* there is a buffer of free pages available to give compaction
* a reasonable chance of completing and allocating the page
*/
- balance_gap = min(low_wmark_pages(zone),
- (zone->managed_pages + KSWAPD_ZONE_BALANCE_GAP_RATIO-1) /
- KSWAPD_ZONE_BALANCE_GAP_RATIO);
- watermark = high_wmark_pages(zone) + balance_gap + (2UL << sc->order);
- watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, 0, 0);
+ balance_gap = min(low_wmark_pages(zone), DIV_ROUND_UP(
+ zone->managed_pages, KSWAPD_ZONE_BALANCE_GAP_RATIO));
+ watermark = high_wmark_pages(zone) + balance_gap + (2UL << order);
+ watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, 0);
/*
* If compaction is deferred, reclaim up to a point where
* compaction will have a chance of success when re-enabled
*/
- if (compaction_deferred(zone, sc->order))
+ if (compaction_deferred(zone, order))
return watermark_ok;
- /* If compaction is not ready to start, keep reclaiming */
- if (!compaction_suitable(zone, sc->order))
+ /*
+ * If compaction is not ready to start and allocation is not likely
+ * to succeed without it, then keep reclaiming.
+ */
+ if (compaction_suitable(zone, order, 0, 0) == COMPACT_SKIPPED)
return false;
return watermark_ok;
* If a zone is deemed to be full of pinned pages then just give it a light
* scan then give up on it.
*
- * This function returns true if a zone is being reclaimed for a costly
- * high-order allocation and compaction is ready to begin. This indicates to
- * the caller that it should consider retrying the allocation instead of
- * further reclaim.
+ * Returns true if a zone was reclaimable.
*/
static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
{
struct zone *zone;
unsigned long nr_soft_reclaimed;
unsigned long nr_soft_scanned;
- bool aborted_reclaim = false;
+ gfp_t orig_mask;
+ enum zone_type requested_highidx = gfp_zone(sc->gfp_mask);
+ bool reclaimable = false;
/*
* If the number of buffer_heads in the machine exceeds the maximum
* allowed level, force direct reclaim to scan the highmem zone as
* highmem pages could be pinning lowmem pages storing buffer_heads
*/
+ orig_mask = sc->gfp_mask;
if (buffer_heads_over_limit)
sc->gfp_mask |= __GFP_HIGHMEM;
for_each_zone_zonelist_nodemask(zone, z, zonelist,
gfp_zone(sc->gfp_mask), sc->nodemask) {
+ enum zone_type classzone_idx;
+
if (!populated_zone(zone))
continue;
+
+ classzone_idx = requested_highidx;
+ while (!populated_zone(zone->zone_pgdat->node_zones +
+ classzone_idx))
+ classzone_idx--;
+
/*
* Take care memory controller reclaiming has small influence
* to global LRU.
*/
if (global_reclaim(sc)) {
- if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
+ if (!cpuset_zone_allowed(zone,
+ GFP_KERNEL | __GFP_HARDWALL))
continue;
- if (zone->all_unreclaimable &&
- sc->priority != DEF_PRIORITY)
+
+ if (sc->priority != DEF_PRIORITY &&
+ !zone_reclaimable(zone))
continue; /* Let kswapd poll it */
- if (IS_ENABLED(CONFIG_COMPACTION)) {
- /*
- * If we already have plenty of memory free for
- * compaction in this zone, don't free any more.
- * Even though compaction is invoked for any
- * non-zero order, only frequent costly order
- * reclamation is disruptive enough to become a
- * noticeable problem, like transparent huge
- * page allocations.
- */
- if (compaction_ready(zone, sc)) {
- aborted_reclaim = true;
- continue;
- }
+
+ /*
+ * If we already have plenty of memory free for
+ * compaction in this zone, don't free any more.
+ * Even though compaction is invoked for any
+ * non-zero order, only frequent costly order
+ * reclamation is disruptive enough to become a
+ * noticeable problem, like transparent huge
+ * page allocations.
+ */
+ if (IS_ENABLED(CONFIG_COMPACTION) &&
+ sc->order > PAGE_ALLOC_COSTLY_ORDER &&
+ zonelist_zone_idx(z) <= requested_highidx &&
+ compaction_ready(zone, sc->order)) {
+ sc->compaction_ready = true;
+ continue;
}
+
/*
* This steals pages from memory cgroups over softlimit
* and returns the number of reclaimed pages and
&nr_soft_scanned);
sc->nr_reclaimed += nr_soft_reclaimed;
sc->nr_scanned += nr_soft_scanned;
+ if (nr_soft_reclaimed)
+ reclaimable = true;
/* need some check for avoid more shrink_zone() */
}
- shrink_zone(zone, sc);
- }
-
- return aborted_reclaim;
-}
-
-static bool zone_reclaimable(struct zone *zone)
-{
- return zone->pages_scanned < zone_reclaimable_pages(zone) * 6;
-}
-
-/* All zones in zonelist are unreclaimable? */
-static bool all_unreclaimable(struct zonelist *zonelist,
- struct scan_control *sc)
-{
- struct zoneref *z;
- struct zone *zone;
+ if (shrink_zone(zone, sc, zone_idx(zone) == classzone_idx))
+ reclaimable = true;
- for_each_zone_zonelist_nodemask(zone, z, zonelist,
- gfp_zone(sc->gfp_mask), sc->nodemask) {
- if (!populated_zone(zone))
- continue;
- if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
- continue;
- if (!zone->all_unreclaimable)
- return false;
+ if (global_reclaim(sc) &&
+ !reclaimable && zone_reclaimable(zone))
+ reclaimable = true;
}
- return true;
+ /*
+ * Restore to original mask to avoid the impact on the caller if we
+ * promoted it to __GFP_HIGHMEM.
+ */
+ sc->gfp_mask = orig_mask;
+
+ return reclaimable;
}
/*
* else, the number of pages reclaimed
*/
static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
- struct scan_control *sc,
- struct shrink_control *shrink)
+ struct scan_control *sc)
{
+ int initial_priority = sc->priority;
unsigned long total_scanned = 0;
- struct reclaim_state *reclaim_state = current->reclaim_state;
- struct zoneref *z;
- struct zone *zone;
unsigned long writeback_threshold;
- bool aborted_reclaim;
-
+ bool zones_reclaimable;
+retry:
delayacct_freepages_start();
if (global_reclaim(sc))
vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup,
sc->priority);
sc->nr_scanned = 0;
- aborted_reclaim = shrink_zones(zonelist, sc);
+ zones_reclaimable = shrink_zones(zonelist, sc);
- /*
- * Don't shrink slabs when reclaiming memory from
- * over limit cgroups
- */
- if (global_reclaim(sc)) {
- unsigned long lru_pages = 0;
- for_each_zone_zonelist(zone, z, zonelist,
- gfp_zone(sc->gfp_mask)) {
- if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
- continue;
-
- lru_pages += zone_reclaimable_pages(zone);
- }
-
- shrink_slab(shrink, sc->nr_scanned, lru_pages);
- if (reclaim_state) {
- sc->nr_reclaimed += reclaim_state->reclaimed_slab;
- reclaim_state->reclaimed_slab = 0;
- }
- }
total_scanned += sc->nr_scanned;
if (sc->nr_reclaimed >= sc->nr_to_reclaim)
- goto out;
+ break;
+
+ if (sc->compaction_ready)
+ break;
/*
* If we're getting trouble reclaiming, start doing
WB_REASON_TRY_TO_FREE_PAGES);
sc->may_writepage = 1;
}
-
- /* Take a nap, wait for some writeback to complete */
- if (!sc->hibernation_mode && sc->nr_scanned &&
- sc->priority < DEF_PRIORITY - 2) {
- struct zone *preferred_zone;
-
- first_zones_zonelist(zonelist, gfp_zone(sc->gfp_mask),
- &cpuset_current_mems_allowed,
- &preferred_zone);
- wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/10);
- }
} while (--sc->priority >= 0);
-out:
delayacct_freepages_end();
if (sc->nr_reclaimed)
return sc->nr_reclaimed;
- /*
- * As hibernation is going on, kswapd is freezed so that it can't mark
- * the zone into all_unreclaimable. Thus bypassing all_unreclaimable
- * check.
- */
- if (oom_killer_disabled)
- return 0;
-
/* Aborted reclaim to try compaction? don't OOM, then */
- if (aborted_reclaim)
+ if (sc->compaction_ready)
return 1;
- /* top priority shrink_zones still had more to do? don't OOM, then */
- if (global_reclaim(sc) && !all_unreclaimable(zonelist, sc))
+ /* Untapped cgroup reserves? Don't OOM, retry. */
+ if (!sc->may_thrash) {
+ sc->priority = initial_priority;
+ sc->may_thrash = 1;
+ goto retry;
+ }
+
+ /* Any of the zones still reclaimable? Don't OOM. */
+ if (zones_reclaimable)
return 1;
return 0;
for (i = 0; i <= ZONE_NORMAL; i++) {
zone = &pgdat->node_zones[i];
+ if (!populated_zone(zone) ||
+ zone_reclaimable_pages(zone) == 0)
+ continue;
+
pfmemalloc_reserve += min_wmark_pages(zone);
free_pages += zone_page_state(zone, NR_FREE_PAGES);
}
+ /* If there are no reserves (unexpected config) then do not throttle */
+ if (!pfmemalloc_reserve)
+ return true;
+
wmark_ok = free_pages > pfmemalloc_reserve / 2;
/* kswapd must be awake if processes are being throttled */
static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,
nodemask_t *nodemask)
{
+ struct zoneref *z;
struct zone *zone;
- int high_zoneidx = gfp_zone(gfp_mask);
- pg_data_t *pgdat;
+ pg_data_t *pgdat = NULL;
/*
* Kernel threads should not be throttled as they may be indirectly
if (fatal_signal_pending(current))
goto out;
- /* Check if the pfmemalloc reserves are ok */
- first_zones_zonelist(zonelist, high_zoneidx, NULL, &zone);
- pgdat = zone->zone_pgdat;
- if (pfmemalloc_watermark_ok(pgdat))
+ /*
+ * Check if the pfmemalloc reserves are ok by finding the first node
+ * with a usable ZONE_NORMAL or lower zone. The expectation is that
+ * GFP_KERNEL will be required for allocating network buffers when
+ * swapping over the network so ZONE_HIGHMEM is unusable.
+ *
+ * Throttling is based on the first usable node and throttled processes
+ * wait on a queue until kswapd makes progress and wakes them. There
+ * is an affinity then between processes waking up and where reclaim
+ * progress has been made assuming the process wakes on the same node.
+ * More importantly, processes running on remote nodes will not compete
+ * for remote pfmemalloc reserves and processes on different nodes
+ * should make reasonable progress.
+ */
+ for_each_zone_zonelist_nodemask(zone, z, zonelist,
+ gfp_zone(gfp_mask), nodemask) {
+ if (zone_idx(zone) > ZONE_NORMAL)
+ continue;
+
+ /* Throttle based on the first usable node */
+ pgdat = zone->zone_pgdat;
+ if (pfmemalloc_watermark_ok(pgdat))
+ goto out;
+ break;
+ }
+
+ /* If no zone was usable by the allocation flags then do not throttle */
+ if (!pgdat)
goto out;
/* Account for the throttling */
{
unsigned long nr_reclaimed;
struct scan_control sc = {
+ .nr_to_reclaim = SWAP_CLUSTER_MAX,
.gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)),
+ .order = order,
+ .nodemask = nodemask,
+ .priority = DEF_PRIORITY,
.may_writepage = !laptop_mode,
- .nr_to_reclaim = SWAP_CLUSTER_MAX,
.may_unmap = 1,
.may_swap = 1,
- .order = order,
- .priority = DEF_PRIORITY,
- .target_mem_cgroup = NULL,
- .nodemask = nodemask,
- };
- struct shrink_control shrink = {
- .gfp_mask = sc.gfp_mask,
};
/*
sc.may_writepage,
gfp_mask);
- nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink);
+ nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
trace_mm_vmscan_direct_reclaim_end(nr_reclaimed);
unsigned long *nr_scanned)
{
struct scan_control sc = {
- .nr_scanned = 0,
.nr_to_reclaim = SWAP_CLUSTER_MAX,
+ .target_mem_cgroup = memcg,
.may_writepage = !laptop_mode,
.may_unmap = 1,
.may_swap = !noswap,
- .order = 0,
- .priority = 0,
- .target_mem_cgroup = memcg,
};
struct lruvec *lruvec = mem_cgroup_zone_lruvec(zone, memcg);
+ int swappiness = mem_cgroup_swappiness(memcg);
+ unsigned long lru_pages;
sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
* will pick up pages from other mem cgroup's as well. We hack
* the priority and make it zero.
*/
- shrink_lruvec(lruvec, &sc);
+ shrink_lruvec(lruvec, swappiness, &sc, &lru_pages);
trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
}
unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
+ unsigned long nr_pages,
gfp_t gfp_mask,
- bool noswap)
+ bool may_swap)
{
struct zonelist *zonelist;
unsigned long nr_reclaimed;
int nid;
struct scan_control sc = {
- .may_writepage = !laptop_mode,
- .may_unmap = 1,
- .may_swap = !noswap,
- .nr_to_reclaim = SWAP_CLUSTER_MAX,
- .order = 0,
- .priority = DEF_PRIORITY,
- .target_mem_cgroup = memcg,
- .nodemask = NULL, /* we don't care the placement */
+ .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK),
- };
- struct shrink_control shrink = {
- .gfp_mask = sc.gfp_mask,
+ .target_mem_cgroup = memcg,
+ .priority = DEF_PRIORITY,
+ .may_writepage = !laptop_mode,
+ .may_unmap = 1,
+ .may_swap = may_swap,
};
/*
sc.may_writepage,
sc.gfp_mask);
- nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink);
+ current->flags |= PF_MEMALLOC;
+ nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
+ current->flags &= ~PF_MEMALLOC;
trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed);
unsigned long balance_gap, int classzone_idx)
{
if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone) +
- balance_gap, classzone_idx, 0))
+ balance_gap, classzone_idx))
return false;
- if (IS_ENABLED(CONFIG_COMPACTION) && order &&
- !compaction_suitable(zone, order))
+ if (IS_ENABLED(CONFIG_COMPACTION) && order && compaction_suitable(zone,
+ order, 0, classzone_idx) == COMPACT_SKIPPED)
return false;
return true;
* DEF_PRIORITY. Effectively, it considers them balanced so
* they must be considered balanced here as well!
*/
- if (zone->all_unreclaimable) {
+ if (!zone_reclaimable(zone)) {
balanced_pages += zone->managed_pages;
continue;
}
return false;
/*
- * There is a potential race between when kswapd checks its watermarks
- * and a process gets throttled. There is also a potential race if
- * processes get throttled, kswapd wakes, a large process exits therby
- * balancing the zones that causes kswapd to miss a wakeup. If kswapd
- * is going to sleep, no process should be sleeping on pfmemalloc_wait
- * so wake them now if necessary. If necessary, processes will wake
- * kswapd and get throttled again
+ * The throttled processes are normally woken up in balance_pgdat() as
+ * soon as pfmemalloc_watermark_ok() is true. But there is a potential
+ * race between when kswapd checks the watermarks and a process gets
+ * throttled. There is also a potential race if processes get
+ * throttled, kswapd wakes, a large process exits thereby balancing the
+ * zones, which causes kswapd to exit balance_pgdat() before reaching
+ * the wake up checks. If kswapd is going to sleep, no process should
+ * be sleeping on pfmemalloc_wait, so wake them now if necessary. If
+ * the wake up is premature, processes will wake kswapd and get
+ * throttled again. The difference from wake ups in balance_pgdat() is
+ * that here we are under prepare_to_wait().
*/
- if (waitqueue_active(&pgdat->pfmemalloc_wait)) {
- wake_up(&pgdat->pfmemalloc_wait);
- return false;
- }
+ if (waitqueue_active(&pgdat->pfmemalloc_wait))
+ wake_up_all(&pgdat->pfmemalloc_wait);
return pgdat_balanced(pgdat, order, classzone_idx);
}
+/*
+ * kswapd shrinks the zone by the number of pages required to reach
+ * the high watermark.
+ *
+ * Returns true if kswapd scanned at least the requested number of pages to
+ * reclaim or if the lack of progress was due to pages under writeback.
+ * This is used to determine if the scanning priority needs to be raised.
+ */
+static bool kswapd_shrink_zone(struct zone *zone,
+ int classzone_idx,
+ struct scan_control *sc,
+ unsigned long *nr_attempted)
+{
+ int testorder = sc->order;
+ unsigned long balance_gap;
+ bool lowmem_pressure;
+
+ /* Reclaim above the high watermark. */
+ sc->nr_to_reclaim = max(SWAP_CLUSTER_MAX, high_wmark_pages(zone));
+
+ /*
+ * Kswapd reclaims only single pages with compaction enabled. Trying
+ * too hard to reclaim until contiguous free pages have become
+ * available can hurt performance by evicting too much useful data
+ * from memory. Do not reclaim more than needed for compaction.
+ */
+ if (IS_ENABLED(CONFIG_COMPACTION) && sc->order &&
+ compaction_suitable(zone, sc->order, 0, classzone_idx)
+ != COMPACT_SKIPPED)
+ testorder = 0;
+
+ /*
+ * We put equal pressure on every zone, unless one zone has way too
+ * many pages free already. The "too many pages" is defined as the
+ * high wmark plus a "gap" where the gap is either the low
+ * watermark or 1% of the zone, whichever is smaller.
+ */
+ balance_gap = min(low_wmark_pages(zone), DIV_ROUND_UP(
+ zone->managed_pages, KSWAPD_ZONE_BALANCE_GAP_RATIO));
+
+ /*
+ * If there is no low memory pressure or the zone is balanced then no
+ * reclaim is necessary
+ */
+ lowmem_pressure = (buffer_heads_over_limit && is_highmem(zone));
+ if (!lowmem_pressure && zone_balanced(zone, testorder,
+ balance_gap, classzone_idx))
+ return true;
+
+ shrink_zone(zone, sc, zone_idx(zone) == classzone_idx);
+
+ /* Account for the number of pages attempted to reclaim */
+ *nr_attempted += sc->nr_to_reclaim;
+
+ clear_bit(ZONE_WRITEBACK, &zone->flags);
+
+ /*
+ * If a zone reaches its high watermark, consider it to be no longer
+ * congested. It's possible there are dirty pages backed by congested
+ * BDIs but as pressure is relieved, speculatively avoid congestion
+ * waits.
+ */
+ if (zone_reclaimable(zone) &&
+ zone_balanced(zone, testorder, 0, classzone_idx)) {
+ clear_bit(ZONE_CONGESTED, &zone->flags);
+ clear_bit(ZONE_DIRTY, &zone->flags);
+ }
+
+ return sc->nr_scanned >= sc->nr_to_reclaim;
+}
+
/*
* For kswapd, balance_pgdat() will work across all this node's zones until
* they are all at high_wmark_pages(zone).
static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
int *classzone_idx)
{
- bool pgdat_is_balanced = false;
int i;
int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
- struct reclaim_state *reclaim_state = current->reclaim_state;
unsigned long nr_soft_reclaimed;
unsigned long nr_soft_scanned;
struct scan_control sc = {
.gfp_mask = GFP_KERNEL,
+ .order = order,
+ .priority = DEF_PRIORITY,
+ .may_writepage = !laptop_mode,
.may_unmap = 1,
.may_swap = 1,
- /*
- * kswapd doesn't want to be bailed out while reclaim. because
- * we want to put equal scanning pressure on each zone.
- */
- .nr_to_reclaim = ULONG_MAX,
- .order = order,
- .target_mem_cgroup = NULL,
- };
- struct shrink_control shrink = {
- .gfp_mask = sc.gfp_mask,
};
-loop_again:
- sc.priority = DEF_PRIORITY;
- sc.nr_reclaimed = 0;
- sc.may_writepage = !laptop_mode;
count_vm_event(PAGEOUTRUN);
do {
- unsigned long lru_pages = 0;
+ unsigned long nr_attempted = 0;
+ bool raise_priority = true;
+ bool pgdat_needs_compaction = (order > 0);
+
+ sc.nr_reclaimed = 0;
/*
* Scan in the highmem->dma direction for the highest
if (!populated_zone(zone))
continue;
- if (zone->all_unreclaimable &&
- sc.priority != DEF_PRIORITY)
+ if (sc.priority != DEF_PRIORITY &&
+ !zone_reclaimable(zone))
continue;
/*
end_zone = i;
break;
} else {
- /* If balanced, clear the congested flag */
- zone_clear_flag(zone, ZONE_CONGESTED);
+ /*
+ * If balanced, clear the dirty and congested
+ * flags
+ */
+ clear_bit(ZONE_CONGESTED, &zone->flags);
+ clear_bit(ZONE_DIRTY, &zone->flags);
}
}
- if (i < 0) {
- pgdat_is_balanced = true;
+ if (i < 0)
goto out;
- }
for (i = 0; i <= end_zone; i++) {
struct zone *zone = pgdat->node_zones + i;
- lru_pages += zone_reclaimable_pages(zone);
+ if (!populated_zone(zone))
+ continue;
+
+ /*
+ * If any zone is currently balanced then kswapd will
+ * not call compaction as it is expected that the
+ * necessary pages are already available.
+ */
+ if (pgdat_needs_compaction &&
+ zone_watermark_ok(zone, order,
+ low_wmark_pages(zone),
+ *classzone_idx, 0))
+ pgdat_needs_compaction = false;
}
+ /*
+ * If we're getting trouble reclaiming, start doing writepage
+ * even in laptop mode.
+ */
+ if (sc.priority < DEF_PRIORITY - 2)
+ sc.may_writepage = 1;
+
/*
* Now scan the zone in the dma->highmem direction, stopping
* at the last zone which needs scanning.
*/
for (i = 0; i <= end_zone; i++) {
struct zone *zone = pgdat->node_zones + i;
- int nr_slab, testorder;
- unsigned long balance_gap;
if (!populated_zone(zone))
continue;
- if (zone->all_unreclaimable &&
- sc.priority != DEF_PRIORITY)
+ if (sc.priority != DEF_PRIORITY &&
+ !zone_reclaimable(zone))
continue;
sc.nr_scanned = 0;
sc.nr_reclaimed += nr_soft_reclaimed;
/*
- * We put equal pressure on every zone, unless
- * one zone has way too many pages free
- * already. The "too many pages" is defined
- * as the high wmark plus a "gap" where the
- * gap is either the low watermark or 1%
- * of the zone, whichever is smaller.
+ * There should be no need to raise the scanning
+ * priority if enough pages are already being scanned
+ * that that high watermark would be met at 100%
+ * efficiency.
*/
- balance_gap = min(low_wmark_pages(zone),
- (zone->managed_pages +
- KSWAPD_ZONE_BALANCE_GAP_RATIO-1) /
- KSWAPD_ZONE_BALANCE_GAP_RATIO);
- /*
- * Kswapd reclaims only single pages with compaction
- * enabled. Trying too hard to reclaim until contiguous
- * free pages have become available can hurt performance
- * by evicting too much useful data from memory.
- * Do not reclaim more than needed for compaction.
- */
- testorder = order;
- if (IS_ENABLED(CONFIG_COMPACTION) && order &&
- compaction_suitable(zone, order) !=
- COMPACT_SKIPPED)
- testorder = 0;
-
- if ((buffer_heads_over_limit && is_highmem_idx(i)) ||
- !zone_balanced(zone, testorder,
- balance_gap, end_zone)) {
- shrink_zone(zone, &sc);
-
- reclaim_state->reclaimed_slab = 0;
- nr_slab = shrink_slab(&shrink, sc.nr_scanned, lru_pages);
- sc.nr_reclaimed += reclaim_state->reclaimed_slab;
-
- if (nr_slab == 0 && !zone_reclaimable(zone))
- zone->all_unreclaimable = 1;
- }
-
- /*
- * If we're getting trouble reclaiming, start doing
- * writepage even in laptop mode.
- */
- if (sc.priority < DEF_PRIORITY - 2)
- sc.may_writepage = 1;
-
- if (zone->all_unreclaimable) {
- if (end_zone && end_zone == i)
- end_zone--;
- continue;
- }
-
- if (zone_balanced(zone, testorder, 0, end_zone))
- /*
- * If a zone reaches its high watermark,
- * consider it to be no longer congested. It's
- * possible there are dirty pages backed by
- * congested BDIs but as pressure is relieved,
- * speculatively avoid congestion waits
- */
- zone_clear_flag(zone, ZONE_CONGESTED);
+ if (kswapd_shrink_zone(zone, end_zone,
+ &sc, &nr_attempted))
+ raise_priority = false;
}
/*
*/
if (waitqueue_active(&pgdat->pfmemalloc_wait) &&
pfmemalloc_watermark_ok(pgdat))
- wake_up(&pgdat->pfmemalloc_wait);
-
- if (pgdat_balanced(pgdat, order, *classzone_idx)) {
- pgdat_is_balanced = true;
- break; /* kswapd: all done */
- }
+ wake_up_all(&pgdat->pfmemalloc_wait);
/*
- * We do this so kswapd doesn't build up large priorities for
- * example when it is freeing in parallel with allocators. It
- * matches the direct reclaim path behaviour in terms of impact
- * on zone->*_priority.
+ * Fragmentation may mean that the system cannot be rebalanced
+ * for high-order allocations in all zones. If twice the
+ * allocation size has been reclaimed and the zones are still
+ * not balanced then recheck the watermarks at order-0 to
+ * prevent kswapd reclaiming excessively. Assume that a
+ * process requested a high-order can direct reclaim/compact.
*/
- if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX)
- break;
- } while (--sc.priority >= 0);
-
-out:
- if (!pgdat_is_balanced) {
- cond_resched();
+ if (order && sc.nr_reclaimed >= 2UL << order)
+ order = sc.order = 0;
- try_to_freeze();
+ /* Check if kswapd should be suspending */
+ if (try_to_freeze() || kthread_should_stop())
+ break;
/*
- * Fragmentation may mean that the system cannot be
- * rebalanced for high-order allocations in all zones.
- * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX,
- * it means the zones have been fully scanned and are still
- * not balanced. For high-order allocations, there is
- * little point trying all over again as kswapd may
- * infinite loop.
- *
- * Instead, recheck all watermarks at order-0 as they
- * are the most important. If watermarks are ok, kswapd will go
- * back to sleep. High-order users can still perform direct
- * reclaim if they wish.
+ * Compact if necessary and kswapd is reclaiming at least the
+ * high watermark number of pages as requsted
*/
- if (sc.nr_reclaimed < SWAP_CLUSTER_MAX)
- order = sc.order = 0;
-
- goto loop_again;
- }
-
- /*
- * If kswapd was reclaiming at a higher order, it has the option of
- * sleeping without all zones being balanced. Before it does, it must
- * ensure that the watermarks for order-0 on *all* zones are met and
- * that the congestion flags are cleared. The congestion flag must
- * be cleared as kswapd is the only mechanism that clears the flag
- * and it is potentially going to sleep here.
- */
- if (order) {
- int zones_need_compaction = 1;
-
- for (i = 0; i <= end_zone; i++) {
- struct zone *zone = pgdat->node_zones + i;
-
- if (!populated_zone(zone))
- continue;
-
- /* Check if the memory needs to be defragmented. */
- if (zone_watermark_ok(zone, order,
- low_wmark_pages(zone), *classzone_idx, 0))
- zones_need_compaction = 0;
- }
-
- if (zones_need_compaction)
+ if (pgdat_needs_compaction && sc.nr_reclaimed > nr_attempted)
compact_pgdat(pgdat, order);
- }
+ /*
+ * Raise priority if scanning rate is too low or there was no
+ * progress in reclaiming pages
+ */
+ if (raise_priority || !sc.nr_reclaimed)
+ sc.priority--;
+ } while (sc.priority >= 1 &&
+ !pgdat_balanced(pgdat, order, *classzone_idx));
+
+out:
/*
* Return the order we were reclaiming at so prepare_kswapd_sleep()
* makes a decision on the order we were last reclaiming at. However,
}
}
+ tsk->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD);
current->reclaim_state = NULL;
+ lockdep_clear_current_reclaim_state();
+
return 0;
}
if (!populated_zone(zone))
return;
- if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
+ if (!cpuset_zone_allowed(zone, GFP_KERNEL | __GFP_HARDWALL))
return;
pgdat = zone->zone_pgdat;
if (pgdat->kswapd_max_order < order) {
}
if (!waitqueue_active(&pgdat->kswapd_wait))
return;
- if (zone_watermark_ok_safe(zone, order, low_wmark_pages(zone), 0, 0))
+ if (zone_balanced(zone, order, 0, 0))
return;
trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order);
wake_up_interruptible(&pgdat->kswapd_wait);
}
-/*
- * The reclaimable count would be mostly accurate.
- * The less reclaimable pages may be
- * - mlocked pages, which will be moved to unevictable list when encountered
- * - mapped pages, which may require several travels to be reclaimed
- * - dirty pages, which is not "instantly" reclaimable
- */
-unsigned long global_reclaimable_pages(void)
-{
- int nr;
-
- nr = global_page_state(NR_ACTIVE_FILE) +
- global_page_state(NR_INACTIVE_FILE);
-
- if (get_nr_swap_pages() > 0)
- nr += global_page_state(NR_ACTIVE_ANON) +
- global_page_state(NR_INACTIVE_ANON);
-
- return nr;
-}
-
-unsigned long zone_reclaimable_pages(struct zone *zone)
-{
- int nr;
-
- nr = zone_page_state(zone, NR_ACTIVE_FILE) +
- zone_page_state(zone, NR_INACTIVE_FILE);
-
- if (get_nr_swap_pages() > 0)
- nr += zone_page_state(zone, NR_ACTIVE_ANON) +
- zone_page_state(zone, NR_INACTIVE_ANON);
-
- return nr;
-}
-
#ifdef CONFIG_HIBERNATION
/*
* Try to free `nr_to_reclaim' of memory, system-wide, and return the number of
{
struct reclaim_state reclaim_state;
struct scan_control sc = {
+ .nr_to_reclaim = nr_to_reclaim,
.gfp_mask = GFP_HIGHUSER_MOVABLE,
- .may_swap = 1,
- .may_unmap = 1,
+ .priority = DEF_PRIORITY,
.may_writepage = 1,
- .nr_to_reclaim = nr_to_reclaim,
+ .may_unmap = 1,
+ .may_swap = 1,
.hibernation_mode = 1,
- .order = 0,
- .priority = DEF_PRIORITY,
- };
- struct shrink_control shrink = {
- .gfp_mask = sc.gfp_mask,
};
struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
struct task_struct *p = current;
reclaim_state.reclaimed_slab = 0;
p->reclaim_state = &reclaim_state;
- nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink);
+ nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
p->reclaim_state = NULL;
lockdep_clear_current_reclaim_state();
/*
* Called by memory hotplug when all memory in a node is offlined. Caller must
- * hold lock_memory_hotplug().
+ * hold mem_hotplug_begin/end().
*/
void kswapd_stop(int nid)
{
#define RECLAIM_OFF 0
#define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */
#define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */
-#define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */
+#define RECLAIM_UNMAP (1<<2) /* Unmap pages during reclaim */
/*
* Priority for ZONE_RECLAIM. This determines the fraction of pages
}
/* Work out how many page cache pages we can reclaim in this reclaim_mode */
-static long zone_pagecache_reclaimable(struct zone *zone)
+static unsigned long zone_pagecache_reclaimable(struct zone *zone)
{
- long nr_pagecache_reclaimable;
- long delta = 0;
+ unsigned long nr_pagecache_reclaimable;
+ unsigned long delta = 0;
/*
- * If RECLAIM_SWAP is set, then all file pages are considered
+ * If RECLAIM_UNMAP is set, then all file pages are considered
* potentially reclaimable. Otherwise, we have to worry about
* pages like swapcache and zone_unmapped_file_pages() provides
* a better estimate
*/
- if (zone_reclaim_mode & RECLAIM_SWAP)
+ if (zone_reclaim_mode & RECLAIM_UNMAP)
nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES);
else
nr_pagecache_reclaimable = zone_unmapped_file_pages(zone);
struct task_struct *p = current;
struct reclaim_state reclaim_state;
struct scan_control sc = {
- .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
- .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP),
- .may_swap = 1,
.nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
.gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)),
.order = order,
.priority = ZONE_RECLAIM_PRIORITY,
+ .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
+ .may_unmap = !!(zone_reclaim_mode & RECLAIM_UNMAP),
+ .may_swap = 1,
};
- struct shrink_control shrink = {
- .gfp_mask = sc.gfp_mask,
- };
- unsigned long nr_slab_pages0, nr_slab_pages1;
cond_resched();
/*
- * We need to be able to allocate from the reserves for RECLAIM_SWAP
+ * We need to be able to allocate from the reserves for RECLAIM_UNMAP
* and we also need to be able to write out pages for RECLAIM_WRITE
- * and RECLAIM_SWAP.
+ * and RECLAIM_UNMAP.
*/
p->flags |= PF_MEMALLOC | PF_SWAPWRITE;
lockdep_set_current_reclaim_state(gfp_mask);
* priorities until we have enough memory freed.
*/
do {
- shrink_zone(zone, &sc);
+ shrink_zone(zone, &sc, true);
} while (sc.nr_reclaimed < nr_pages && --sc.priority >= 0);
}
- nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
- if (nr_slab_pages0 > zone->min_slab_pages) {
- /*
- * shrink_slab() does not currently allow us to determine how
- * many pages were freed in this zone. So we take the current
- * number of slab pages and shake the slab until it is reduced
- * by the same nr_pages that we used for reclaiming unmapped
- * pages.
- *
- * Note that shrink_slab will free memory on all zones and may
- * take a long time.
- */
- for (;;) {
- unsigned long lru_pages = zone_reclaimable_pages(zone);
-
- /* No reclaimable slab or very low memory pressure */
- if (!shrink_slab(&shrink, sc.nr_scanned, lru_pages))
- break;
-
- /* Freed enough memory */
- nr_slab_pages1 = zone_page_state(zone,
- NR_SLAB_RECLAIMABLE);
- if (nr_slab_pages1 + nr_pages <= nr_slab_pages0)
- break;
- }
-
- /*
- * Update nr_reclaimed by the number of slab pages we
- * reclaimed from this zone.
- */
- nr_slab_pages1 = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
- if (nr_slab_pages1 < nr_slab_pages0)
- sc.nr_reclaimed += nr_slab_pages0 - nr_slab_pages1;
- }
-
p->reclaim_state = NULL;
current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE);
lockdep_clear_current_reclaim_state();
zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages)
return ZONE_RECLAIM_FULL;
- if (zone->all_unreclaimable)
+ if (!zone_reclaimable(zone))
return ZONE_RECLAIM_FULL;
/*
* Do not scan if the allocation should not be delayed.
*/
- if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC))
+ if (!gfpflags_allow_blocking(gfp_mask) || (current->flags & PF_MEMALLOC))
return ZONE_RECLAIM_NOSCAN;
/*
if (node_state(node_id, N_CPU) && node_id != numa_node_id())
return ZONE_RECLAIM_NOSCAN;
- if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED))
+ if (test_and_set_bit(ZONE_RECLAIM_LOCKED, &zone->flags))
return ZONE_RECLAIM_NOSCAN;
ret = __zone_reclaim(zone, gfp_mask, order);
- zone_clear_flag(zone, ZONE_RECLAIM_LOCKED);
+ clear_bit(ZONE_RECLAIM_LOCKED, &zone->flags);
if (!ret)
count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED);
if (page_evictable(page)) {
enum lru_list lru = page_lru_base_type(page);
- VM_BUG_ON(PageActive(page));
+ VM_BUG_ON_PAGE(PageActive(page), page);
ClearPageUnevictable(page);
del_page_from_lru_list(page, lruvec, LRU_UNEVICTABLE);
add_page_to_lru_list(page, lruvec, lru);
}
}
#endif /* CONFIG_SHMEM */
-
-static void warn_scan_unevictable_pages(void)
-{
- printk_once(KERN_WARNING
- "%s: The scan_unevictable_pages sysctl/node-interface has been "
- "disabled for lack of a legitimate use case. If you have "
- "one, please send an email to linux-mm@kvack.org.\n",
- current->comm);
-}
-
-/*
- * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of
- * all nodes' unevictable lists for evictable pages
- */
-unsigned long scan_unevictable_pages;
-
-int scan_unevictable_handler(struct ctl_table *table, int write,
- void __user *buffer,
- size_t *length, loff_t *ppos)
-{
- warn_scan_unevictable_pages();
- proc_doulongvec_minmax(table, write, buffer, length, ppos);
- scan_unevictable_pages = 0;
- return 0;
-}
-
-#ifdef CONFIG_NUMA
-/*
- * per node 'scan_unevictable_pages' attribute. On demand re-scan of
- * a specified node's per zone unevictable lists for evictable pages.
- */
-
-static ssize_t read_scan_unevictable_node(struct device *dev,
- struct device_attribute *attr,
- char *buf)
-{
- warn_scan_unevictable_pages();
- return sprintf(buf, "0\n"); /* always zero; should fit... */
-}
-
-static ssize_t write_scan_unevictable_node(struct device *dev,
- struct device_attribute *attr,
- const char *buf, size_t count)
-{
- warn_scan_unevictable_pages();
- return 1;
-}
-
-
-static DEVICE_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 device_create_file(&node->dev, &dev_attr_scan_unevictable_pages);
-}
-
-void scan_unevictable_unregister_node(struct node *node)
-{
- device_remove_file(&node->dev, &dev_attr_scan_unevictable_pages);
-}
-#endif
projects / firefly-linux-kernel-4.4.55.git / blobdiff