From: Mel Gorman <mgor...@suse.de> Fix, improve and clean up migrate_misplaced_page() to reuse migrate_pages() and to check for zone watermarks to make sure we don't overload the node.
This was originally based on Peter's patch "mm/migrate: Introduce migrate_misplaced_page()" but borrows extremely heavily from Andrea's "autonuma: memory follows CPU algorithm and task/mm_autonuma stats collection". Based-on-work-by: Lee Schermerhorn <lee.schermerh...@hp.com> Based-on-work-by: Peter Zijlstra <a.p.zijls...@chello.nl> Based-on-work-by: Andrea Arcangeli <aarca...@redhat.com> Signed-off-by: Mel Gorman <mgor...@suse.de> Reviewed-by: Rik van Riel <r...@redhat.com> Cc: Johannes Weiner <han...@cmpxchg.org> Cc: Hugh Dickins <hu...@google.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Linux-MM <linux...@kvack.org> Cc: Peter Zijlstra <a.p.zijls...@chello.nl> Cc: Andrea Arcangeli <aarca...@redhat.com> Link: http://lkml.kernel.org/r/1353064973-26082-14-git-send-email-mgor...@suse.de [ Adapted to the numa/core tree. Kept Mel's patch separate to retain original authorship for the authors. ] Signed-off-by: Ingo Molnar <mi...@kernel.org> --- include/linux/migrate_mode.h | 3 - mm/memory.c | 13 ++-- mm/migrate.c | 143 +++++++++++++++++++++++++++---------------- 3 files changed, 95 insertions(+), 64 deletions(-) diff --git a/include/linux/migrate_mode.h b/include/linux/migrate_mode.h index 40b37dc..ebf3d89 100644 --- a/include/linux/migrate_mode.h +++ b/include/linux/migrate_mode.h @@ -6,14 +6,11 @@ * on most operations but not ->writepage as the potential stall time * is too significant * MIGRATE_SYNC will block when migrating pages - * MIGRATE_FAULT called from the fault path to migrate-on-fault for mempolicy - * this path has an extra reference count */ enum migrate_mode { MIGRATE_ASYNC, MIGRATE_SYNC_LIGHT, MIGRATE_SYNC, - MIGRATE_FAULT, }; #endif /* MIGRATE_MODE_H_INCLUDED */ diff --git a/mm/memory.c b/mm/memory.c index 23ad2eb..52ad29d 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3492,28 +3492,25 @@ out_pte_upgrade_unlock: out_unlock: pte_unmap_unlock(ptep, ptl); -out: + if (page) { task_numa_fault(page_nid, last_cpu, 1); put_page(page); } - +out: return 0; migrate: pte_unmap_unlock(ptep, ptl); - if (!migrate_misplaced_page(page, node)) { - page_nid = node; + if (migrate_misplaced_page(page, node)) { goto out; } + page = NULL; ptep = pte_offset_map_lock(mm, pmd, address, &ptl); - if (!pte_same(*ptep, entry)) { - put_page(page); - page = NULL; + if (!pte_same(*ptep, entry)) goto out_unlock; - } goto out_pte_upgrade_unlock; } diff --git a/mm/migrate.c b/mm/migrate.c index b89062d..16a4709 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -225,7 +225,7 @@ static bool buffer_migrate_lock_buffers(struct buffer_head *head, struct buffer_head *bh = head; /* Simple case, sync compaction */ - if (mode != MIGRATE_ASYNC && mode != MIGRATE_FAULT) { + if (mode != MIGRATE_ASYNC) { do { get_bh(bh); lock_buffer(bh); @@ -282,19 +282,9 @@ static int migrate_page_move_mapping(struct address_space *mapping, int expected_count = 0; void **pslot; - if (mode == MIGRATE_FAULT) { - /* - * MIGRATE_FAULT has an extra reference on the page and - * otherwise acts like ASYNC, no point in delaying the - * fault, we'll try again next time. - */ - expected_count++; - } - if (!mapping) { /* Anonymous page without mapping */ - expected_count += 1; - if (page_count(page) != expected_count) + if (page_count(page) != 1) return -EAGAIN; return 0; } @@ -304,7 +294,7 @@ static int migrate_page_move_mapping(struct address_space *mapping, pslot = radix_tree_lookup_slot(&mapping->page_tree, page_index(page)); - expected_count += 2 + page_has_private(page); + expected_count = 2 + page_has_private(page); if (page_count(page) != expected_count || radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) { spin_unlock_irq(&mapping->tree_lock); @@ -323,7 +313,7 @@ static int migrate_page_move_mapping(struct address_space *mapping, * the mapping back due to an elevated page count, we would have to * block waiting on other references to be dropped. */ - if ((mode == MIGRATE_ASYNC || mode == MIGRATE_FAULT) && head && + if (mode == MIGRATE_ASYNC && head && !buffer_migrate_lock_buffers(head, mode)) { page_unfreeze_refs(page, expected_count); spin_unlock_irq(&mapping->tree_lock); @@ -531,7 +521,7 @@ int buffer_migrate_page(struct address_space *mapping, * with an IRQ-safe spinlock held. In the sync case, the buffers * need to be locked now */ - if (mode != MIGRATE_ASYNC && mode != MIGRATE_FAULT) + if (mode != MIGRATE_ASYNC) BUG_ON(!buffer_migrate_lock_buffers(head, mode)); ClearPagePrivate(page); @@ -697,7 +687,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage, struct anon_vma *anon_vma = NULL; if (!trylock_page(page)) { - if (!force || mode == MIGRATE_ASYNC || mode == MIGRATE_FAULT) + if (!force || mode == MIGRATE_ASYNC) goto out; /* @@ -1415,55 +1405,102 @@ int migrate_vmas(struct mm_struct *mm, const nodemask_t *to, } /* + * Returns true if this is a safe migration target node for misplaced NUMA + * pages. Currently it only checks the watermarks which is a bit crude. + */ +static bool migrate_balanced_pgdat(struct pglist_data *pgdat, + int nr_migrate_pages) +{ + int z; + + for (z = pgdat->nr_zones - 1; z >= 0; z--) { + struct zone *zone = pgdat->node_zones + z; + + if (!populated_zone(zone)) + continue; + + if (zone->all_unreclaimable) + continue; + + /* Avoid waking kswapd by allocating pages_to_migrate pages. */ + if (!zone_watermark_ok(zone, 0, + high_wmark_pages(zone) + + nr_migrate_pages, + 0, 0)) + continue; + return true; + } + return false; +} + +static struct page *alloc_misplaced_dst_page(struct page *page, + unsigned long data, + int **result) +{ + int nid = (int) data; + struct page *newpage; + + newpage = alloc_pages_exact_node(nid, + (GFP_HIGHUSER_MOVABLE | GFP_THISNODE | + __GFP_NOMEMALLOC | __GFP_NORETRY | + __GFP_NOWARN) & + ~GFP_IOFS, 0); + return newpage; +} + +/* * Attempt to migrate a misplaced page to the specified destination - * node. + * node. Caller is expected to have an elevated reference count on + * the page that will be dropped by this function before returning. */ int migrate_misplaced_page(struct page *page, int node) { - struct address_space *mapping = page_mapping(page); - int page_lru = page_is_file_cache(page); - struct page *newpage; - int ret = -EAGAIN; - gfp_t gfp = GFP_HIGHUSER_MOVABLE; + int isolated = 0; + LIST_HEAD(migratepages); /* - * Never wait for allocations just to migrate on fault, but don't dip - * into reserves. And, only accept pages from the specified node. No - * sense migrating to a different "misplaced" page! + * Don't migrate pages that are mapped in multiple processes. + * TODO: Handle false sharing detection instead of this hammer */ - if (mapping) - gfp = mapping_gfp_mask(mapping); - gfp &= ~__GFP_WAIT; - gfp |= __GFP_NOMEMALLOC | GFP_THISNODE; - - newpage = alloc_pages_node(node, gfp, 0); - if (!newpage) { - ret = -ENOMEM; + if (page_mapcount(page) != 1) goto out; - } - if (isolate_lru_page(page)) { - ret = -EBUSY; - goto put_new; + /* Avoid migrating to a node that is nearly full */ + if (migrate_balanced_pgdat(NODE_DATA(node), 1)) { + int page_lru; + + if (isolate_lru_page(page)) { + put_page(page); + goto out; + } + isolated = 1; + + /* + * Page is isolated which takes a reference count so now the + * callers reference can be safely dropped without the page + * disappearing underneath us during migration + */ + put_page(page); + + page_lru = page_is_file_cache(page); + inc_zone_page_state(page, NR_ISOLATED_ANON + page_lru); + list_add(&page->lru, &migratepages); } - inc_zone_page_state(page, NR_ISOLATED_ANON + page_lru); - ret = __unmap_and_move(page, newpage, 0, 0, MIGRATE_FAULT); - /* - * A page that has been migrated has all references removed and will be - * freed. A page that has not been migrated will have kepts its - * references and be restored. - */ - dec_zone_page_state(page, NR_ISOLATED_ANON + page_lru); - putback_lru_page(page); -put_new: - /* - * Move the new page to the LRU. If migration was not successful - * then this will free the page. - */ - putback_lru_page(newpage); + if (isolated) { + int nr_remaining; + + nr_remaining = migrate_pages(&migratepages, + alloc_misplaced_dst_page, + node, false, MIGRATE_ASYNC); + if (nr_remaining) { + putback_lru_pages(&migratepages); + isolated = 0; + } + } + BUG_ON(!list_empty(&migratepages)); out: - return ret; + return isolated; } #endif /* CONFIG_NUMA */ -- 1.7.11.7 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
