mm: numa: Add THP migration for the NUMA working set scanning fault case.
Note: This is very heavily based on a patch from Peter Zijlstra with
fixes from Ingo Molnar, Hugh Dickins and Johannes Weiner. That patch
put a lot of migration logic into mm/huge_memory.c where it does
not belong. This version puts tries to share some of the migration
logic with migrate_misplaced_page. However, it should be noted
that now migrate.c is doing more with the pagetable manipulation
than is preferred. The end result is barely recognisable so as
before, the signed-offs had to be removed but will be re-added if
the original authors are ok with it.
Add THP migration for the NUMA working set scanning fault case.
It uses the page lock to serialize. No migration pte dance is
necessary because the pte is already unmapped when we decide
to migrate.
[dhillf@gmail.com: Fix memory leak on isolation failure]
[dhillf@gmail.com: Fix transfer of last_nid information]
Signed-off-by: Mel Gorman <mgorman@suse.de>
diff --git a/mm/migrate.c b/mm/migrate.c
index 2a5ce13..c940096 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -410,7 +410,7 @@
*/
void migrate_page_copy(struct page *newpage, struct page *page)
{
- if (PageHuge(page))
+ if (PageHuge(page) || PageTransHuge(page))
copy_huge_page(newpage, page);
else
copy_highpage(newpage, page);
@@ -1491,6 +1491,68 @@
return true;
}
+/* Returns true if the node is migrate rate-limited after the update */
+bool numamigrate_update_ratelimit(pg_data_t *pgdat)
+{
+ bool rate_limited = false;
+
+ /*
+ * Rate-limit the amount of data that is being migrated to a node.
+ * Optimal placement is no good if the memory bus is saturated and
+ * all the time is being spent migrating!
+ */
+ spin_lock(&pgdat->numabalancing_migrate_lock);
+ if (time_after(jiffies, pgdat->numabalancing_migrate_next_window)) {
+ pgdat->numabalancing_migrate_nr_pages = 0;
+ pgdat->numabalancing_migrate_next_window = jiffies +
+ msecs_to_jiffies(migrate_interval_millisecs);
+ }
+ if (pgdat->numabalancing_migrate_nr_pages > ratelimit_pages)
+ rate_limited = true;
+ else
+ pgdat->numabalancing_migrate_nr_pages++;
+ spin_unlock(&pgdat->numabalancing_migrate_lock);
+
+ return rate_limited;
+}
+
+int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
+{
+ int ret = 0;
+
+ /* Avoid migrating to a node that is nearly full */
+ if (migrate_balanced_pgdat(pgdat, 1)) {
+ int page_lru;
+
+ if (isolate_lru_page(page)) {
+ put_page(page);
+ return 0;
+ }
+
+ /* Page is isolated */
+ ret = 1;
+ page_lru = page_is_file_cache(page);
+ if (!PageTransHuge(page))
+ inc_zone_page_state(page, NR_ISOLATED_ANON + page_lru);
+ else
+ mod_zone_page_state(page_zone(page),
+ NR_ISOLATED_ANON + page_lru,
+ HPAGE_PMD_NR);
+ }
+
+ /*
+ * Page is either isolated or there is not enough space on the target
+ * node. If isolated, then it has taken a reference count and the
+ * callers reference can be safely dropped without the page
+ * disappearing underneath us during migration. Otherwise the page is
+ * not to be migrated but the callers reference should still be
+ * dropped so it does not leak.
+ */
+ put_page(page);
+
+ return ret;
+}
+
/*
* Attempt to migrate a misplaced page to the specified destination
* node. Caller is expected to have an elevated reference count on
@@ -1500,6 +1562,7 @@
{
pg_data_t *pgdat = NODE_DATA(node);
int isolated = 0;
+ int nr_remaining;
LIST_HEAD(migratepages);
/*
@@ -1516,62 +1579,148 @@
* Optimal placement is no good if the memory bus is saturated and
* all the time is being spent migrating!
*/
- spin_lock(&pgdat->numabalancing_migrate_lock);
- if (time_after(jiffies, pgdat->numabalancing_migrate_next_window)) {
- pgdat->numabalancing_migrate_nr_pages = 0;
- pgdat->numabalancing_migrate_next_window = jiffies +
- msecs_to_jiffies(migrate_interval_millisecs);
- }
- if (pgdat->numabalancing_migrate_nr_pages > ratelimit_pages) {
- spin_unlock(&pgdat->numabalancing_migrate_lock);
+ if (numamigrate_update_ratelimit(pgdat)) {
put_page(page);
goto out;
}
- pgdat->numabalancing_migrate_nr_pages++;
- spin_unlock(&pgdat->numabalancing_migrate_lock);
- /* Avoid migrating to a node that is nearly full */
- if (migrate_balanced_pgdat(pgdat, 1)) {
- int page_lru;
+ isolated = numamigrate_isolate_page(pgdat, page);
+ if (!isolated)
+ goto out;
- if (isolate_lru_page(page)) {
- put_page(page);
- goto out;
- }
- isolated = 1;
-
- page_lru = page_is_file_cache(page);
- inc_zone_page_state(page, NR_ISOLATED_ANON + page_lru);
- list_add(&page->lru, &migratepages);
- }
-
- /*
- * Page is either isolated or there is not enough space on the target
- * node. If isolated, then it has taken a reference count and the
- * callers reference can be safely dropped without the page
- * disappearing underneath us during migration. Otherwise the page is
- * not to be migrated but the callers reference should still be
- * dropped so it does not leak.
- */
- put_page(page);
-
- if (isolated) {
- int nr_remaining;
-
- nr_remaining = migrate_pages(&migratepages,
- alloc_misplaced_dst_page,
- node, false, MIGRATE_ASYNC,
- MR_NUMA_MISPLACED);
- if (nr_remaining) {
- putback_lru_pages(&migratepages);
- isolated = 0;
- } else
- count_vm_numa_event(NUMA_PAGE_MIGRATE);
- }
+ list_add(&page->lru, &migratepages);
+ nr_remaining = migrate_pages(&migratepages,
+ alloc_misplaced_dst_page,
+ node, false, MIGRATE_ASYNC,
+ MR_NUMA_MISPLACED);
+ if (nr_remaining) {
+ putback_lru_pages(&migratepages);
+ isolated = 0;
+ } else
+ count_vm_numa_event(NUMA_PAGE_MIGRATE);
BUG_ON(!list_empty(&migratepages));
out:
return isolated;
}
+
+int migrate_misplaced_transhuge_page(struct mm_struct *mm,
+ struct vm_area_struct *vma,
+ pmd_t *pmd, pmd_t entry,
+ unsigned long address,
+ struct page *page, int node)
+{
+ unsigned long haddr = address & HPAGE_PMD_MASK;
+ pg_data_t *pgdat = NODE_DATA(node);
+ int isolated = 0;
+ struct page *new_page = NULL;
+ struct mem_cgroup *memcg = NULL;
+ int page_lru = page_is_file_cache(page);
+
+ /*
+ * Don't migrate pages that are mapped in multiple processes.
+ * TODO: Handle false sharing detection instead of this hammer
+ */
+ if (page_mapcount(page) != 1)
+ goto out_dropref;
+
+ /*
+ * Rate-limit the amount of data that is being migrated to a node.
+ * Optimal placement is no good if the memory bus is saturated and
+ * all the time is being spent migrating!
+ */
+ if (numamigrate_update_ratelimit(pgdat))
+ goto out_dropref;
+
+ new_page = alloc_pages_node(node,
+ (GFP_TRANSHUGE | GFP_THISNODE) & ~__GFP_WAIT, HPAGE_PMD_ORDER);
+ if (!new_page)
+ goto out_dropref;
+ page_xchg_last_nid(new_page, page_last_nid(page));
+
+ isolated = numamigrate_isolate_page(pgdat, page);
+ if (!isolated) {
+ put_page(new_page);
+ goto out_keep_locked;
+ }
+
+ /* Prepare a page as a migration target */
+ __set_page_locked(new_page);
+ SetPageSwapBacked(new_page);
+
+ /* anon mapping, we can simply copy page->mapping to the new page: */
+ new_page->mapping = page->mapping;
+ new_page->index = page->index;
+ migrate_page_copy(new_page, page);
+ WARN_ON(PageLRU(new_page));
+
+ /* Recheck the target PMD */
+ spin_lock(&mm->page_table_lock);
+ if (unlikely(!pmd_same(*pmd, entry))) {
+ spin_unlock(&mm->page_table_lock);
+
+ /* Reverse changes made by migrate_page_copy() */
+ if (TestClearPageActive(new_page))
+ SetPageActive(page);
+ if (TestClearPageUnevictable(new_page))
+ SetPageUnevictable(page);
+ mlock_migrate_page(page, new_page);
+
+ unlock_page(new_page);
+ put_page(new_page); /* Free it */
+
+ unlock_page(page);
+ putback_lru_page(page);
+
+ count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR);
+ goto out;
+ }
+
+ /*
+ * Traditional migration needs to prepare the memcg charge
+ * transaction early to prevent the old page from being
+ * uncharged when installing migration entries. Here we can
+ * save the potential rollback and start the charge transfer
+ * only when migration is already known to end successfully.
+ */
+ mem_cgroup_prepare_migration(page, new_page, &memcg);
+
+ entry = mk_pmd(new_page, vma->vm_page_prot);
+ entry = pmd_mknonnuma(entry);
+ entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
+ entry = pmd_mkhuge(entry);
+
+ page_add_new_anon_rmap(new_page, vma, haddr);
+
+ set_pmd_at(mm, haddr, pmd, entry);
+ update_mmu_cache_pmd(vma, address, entry);
+ page_remove_rmap(page);
+ /*
+ * Finish the charge transaction under the page table lock to
+ * prevent split_huge_page() from dividing up the charge
+ * before it's fully transferred to the new page.
+ */
+ mem_cgroup_end_migration(memcg, page, new_page, true);
+ spin_unlock(&mm->page_table_lock);
+
+ unlock_page(new_page);
+ unlock_page(page);
+ put_page(page); /* Drop the rmap reference */
+ put_page(page); /* Drop the LRU isolation reference */
+
+ count_vm_events(PGMIGRATE_SUCCESS, HPAGE_PMD_NR);
+ count_vm_numa_events(NUMA_PAGE_MIGRATE, HPAGE_PMD_NR);
+
+out:
+ mod_zone_page_state(page_zone(page),
+ NR_ISOLATED_ANON + page_lru,
+ -HPAGE_PMD_NR);
+ return isolated;
+
+out_dropref:
+ put_page(page);
+out_keep_locked:
+ return 0;
+}
#endif /* CONFIG_NUMA_BALANCING */
#endif /* CONFIG_NUMA */