*
* Copyright IBM Corp. 2007-2010 Mel Gorman <mel@csn.ul.ie>
*/
+#include <linux/cpu.h>
#include <linux/swap.h>
#include <linux/migrate.h>
#include <linux/compaction.h>
#include <linux/balloon_compaction.h>
#include <linux/page-isolation.h>
#include <linux/kasan.h>
+#include <linux/kthread.h>
+#include <linux/freezer.h>
#include "internal.h"
#ifdef CONFIG_COMPACTION
pfn = isolate_migratepages_block(cc, pfn, block_end_pfn,
ISOLATE_UNEVICTABLE);
- /*
- * In case of fatal failure, release everything that might
- * have been isolated in the previous iteration, and signal
- * the failure back to caller.
- */
- if (!pfn) {
- putback_movable_pages(&cc->migratepages);
- cc->nr_migratepages = 0;
+ if (!pfn)
break;
- }
if (cc->nr_migratepages == COMPACT_CLUSTER_MAX)
break;
/*
* Mark that the PG_migrate_skip information should be cleared
- * by kswapd when it goes to sleep. kswapd does not set the
+ * by kswapd when it goes to sleep. kcompactd does not set the
* flag itself as the decision to be clear should be directly
* based on an allocation request.
*/
- if (!current_is_kswapd())
+ if (cc->direct_compaction)
zone->compact_blockskip_flush = true;
return COMPACT_COMPLETE;
/*
* Clear pageblock skip if there were failures recently and compaction
- * is about to be retried after being deferred. kswapd does not do
- * this reset as it'll reset the cached information when going to sleep.
+ * is about to be retried after being deferred.
*/
- if (compaction_restarting(zone, cc->order) && !current_is_kswapd())
+ if (compaction_restarting(zone, cc->order))
__reset_isolation_suitable(zone);
/*
.mode = mode,
.alloc_flags = alloc_flags,
.classzone_idx = classzone_idx,
+ .direct_compaction = true,
};
INIT_LIST_HEAD(&cc.freepages);
INIT_LIST_HEAD(&cc.migratepages);
}
#endif /* CONFIG_SYSFS && CONFIG_NUMA */
+static inline bool kcompactd_work_requested(pg_data_t *pgdat)
+{
+ return pgdat->kcompactd_max_order > 0 || kthread_should_stop();
+}
+
+static bool kcompactd_node_suitable(pg_data_t *pgdat)
+{
+ int zoneid;
+ struct zone *zone;
+ enum zone_type classzone_idx = pgdat->kcompactd_classzone_idx;
+
+ for (zoneid = 0; zoneid < classzone_idx; zoneid++) {
+ zone = &pgdat->node_zones[zoneid];
+
+ if (!populated_zone(zone))
+ continue;
+
+ if (compaction_suitable(zone, pgdat->kcompactd_max_order, 0,
+ classzone_idx) == COMPACT_CONTINUE)
+ return true;
+ }
+
+ return false;
+}
+
+static void kcompactd_do_work(pg_data_t *pgdat)
+{
+ /*
+ * With no special task, compact all zones so that a page of requested
+ * order is allocatable.
+ */
+ int zoneid;
+ struct zone *zone;
+ struct compact_control cc = {
+ .order = pgdat->kcompactd_max_order,
+ .classzone_idx = pgdat->kcompactd_classzone_idx,
+ .mode = MIGRATE_SYNC_LIGHT,
+ .ignore_skip_hint = true,
+
+ };
+ bool success = false;
+
+ trace_mm_compaction_kcompactd_wake(pgdat->node_id, cc.order,
+ cc.classzone_idx);
+ count_vm_event(KCOMPACTD_WAKE);
+
+ for (zoneid = 0; zoneid < cc.classzone_idx; zoneid++) {
+ int status;
+
+ zone = &pgdat->node_zones[zoneid];
+ if (!populated_zone(zone))
+ continue;
+
+ if (compaction_deferred(zone, cc.order))
+ continue;
+
+ if (compaction_suitable(zone, cc.order, 0, zoneid) !=
+ COMPACT_CONTINUE)
+ continue;
+
+ cc.nr_freepages = 0;
+ cc.nr_migratepages = 0;
+ cc.zone = zone;
+ INIT_LIST_HEAD(&cc.freepages);
+ INIT_LIST_HEAD(&cc.migratepages);
+
+ if (kthread_should_stop())
+ return;
+ status = compact_zone(zone, &cc);
+
+ if (zone_watermark_ok(zone, cc.order, low_wmark_pages(zone),
+ cc.classzone_idx, 0)) {
+ success = true;
+ compaction_defer_reset(zone, cc.order, false);
+ } else if (status == COMPACT_COMPLETE) {
+ /*
+ * We use sync migration mode here, so we defer like
+ * sync direct compaction does.
+ */
+ defer_compaction(zone, cc.order);
+ }
+
+ VM_BUG_ON(!list_empty(&cc.freepages));
+ VM_BUG_ON(!list_empty(&cc.migratepages));
+ }
+
+ /*
+ * Regardless of success, we are done until woken up next. But remember
+ * the requested order/classzone_idx in case it was higher/tighter than
+ * our current ones
+ */
+ if (pgdat->kcompactd_max_order <= cc.order)
+ pgdat->kcompactd_max_order = 0;
+ if (pgdat->kcompactd_classzone_idx >= cc.classzone_idx)
+ pgdat->kcompactd_classzone_idx = pgdat->nr_zones - 1;
+}
+
+void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx)
+{
+ if (!order)
+ return;
+
+ if (pgdat->kcompactd_max_order < order)
+ pgdat->kcompactd_max_order = order;
+
+ if (pgdat->kcompactd_classzone_idx > classzone_idx)
+ pgdat->kcompactd_classzone_idx = classzone_idx;
+
+ if (!waitqueue_active(&pgdat->kcompactd_wait))
+ return;
+
+ if (!kcompactd_node_suitable(pgdat))
+ return;
+
+ trace_mm_compaction_wakeup_kcompactd(pgdat->node_id, order,
+ classzone_idx);
+ wake_up_interruptible(&pgdat->kcompactd_wait);
+}
+
+/*
+ * The background compaction daemon, started as a kernel thread
+ * from the init process.
+ */
+static int kcompactd(void *p)
+{
+ pg_data_t *pgdat = (pg_data_t*)p;
+ struct task_struct *tsk = current;
+
+ const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
+
+ if (!cpumask_empty(cpumask))
+ set_cpus_allowed_ptr(tsk, cpumask);
+
+ set_freezable();
+
+ pgdat->kcompactd_max_order = 0;
+ pgdat->kcompactd_classzone_idx = pgdat->nr_zones - 1;
+
+ while (!kthread_should_stop()) {
+ trace_mm_compaction_kcompactd_sleep(pgdat->node_id);
+ wait_event_freezable(pgdat->kcompactd_wait,
+ kcompactd_work_requested(pgdat));
+
+ kcompactd_do_work(pgdat);
+ }
+
+ return 0;
+}
+
+/*
+ * This kcompactd start function will be called by init and node-hot-add.
+ * On node-hot-add, kcompactd will moved to proper cpus if cpus are hot-added.
+ */
+int kcompactd_run(int nid)
+{
+ pg_data_t *pgdat = NODE_DATA(nid);
+ int ret = 0;
+
+ if (pgdat->kcompactd)
+ return 0;
+
+ pgdat->kcompactd = kthread_run(kcompactd, pgdat, "kcompactd%d", nid);
+ if (IS_ERR(pgdat->kcompactd)) {
+ pr_err("Failed to start kcompactd on node %d\n", nid);
+ ret = PTR_ERR(pgdat->kcompactd);
+ pgdat->kcompactd = NULL;
+ }
+ return ret;
+}
+
+/*
+ * Called by memory hotplug when all memory in a node is offlined. Caller must
+ * hold mem_hotplug_begin/end().
+ */
+void kcompactd_stop(int nid)
+{
+ struct task_struct *kcompactd = NODE_DATA(nid)->kcompactd;
+
+ if (kcompactd) {
+ kthread_stop(kcompactd);
+ NODE_DATA(nid)->kcompactd = NULL;
+ }
+}
+
+/*
+ * It's optimal to keep kcompactd on the same CPUs as their memory, but
+ * not required for correctness. So if the last cpu in a node goes
+ * away, we get changed to run anywhere: as the first one comes back,
+ * restore their cpu bindings.
+ */
+static int cpu_callback(struct notifier_block *nfb, unsigned long action,
+ void *hcpu)
+{
+ int nid;
+
+ if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) {
+ for_each_node_state(nid, N_MEMORY) {
+ pg_data_t *pgdat = NODE_DATA(nid);
+ const struct cpumask *mask;
+
+ mask = cpumask_of_node(pgdat->node_id);
+
+ if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids)
+ /* One of our CPUs online: restore mask */
+ set_cpus_allowed_ptr(pgdat->kcompactd, mask);
+ }
+ }
+ return NOTIFY_OK;
+}
+
+static int __init kcompactd_init(void)
+{
+ int nid;
+
+ for_each_node_state(nid, N_MEMORY)
+ kcompactd_run(nid);
+ hotcpu_notifier(cpu_callback, 0);
+ return 0;
+}
+subsys_initcall(kcompactd_init)
+
#endif /* CONFIG_COMPACTION */
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