diff options
| -rw-r--r-- | include/linux/mmzone.h | 6 | ||||
| -rw-r--r-- | mm/page_alloc.c | 138 | ||||
| -rw-r--r-- | mm/vmstat.c | 1 |
3 files changed, 135 insertions, 10 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index b86cfa3313cf..d3bafe4ff32b 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -39,6 +39,8 @@ enum { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE, MIGRATE_RECLAIMABLE, + MIGRATE_PCPTYPES, /* the number of types on the pcp lists */ + MIGRATE_HIGHATOMIC = MIGRATE_PCPTYPES, #ifdef CONFIG_CMA /* * MIGRATE_CMA migration type is designed to mimic the way @@ -61,8 +63,6 @@ enum { MIGRATE_TYPES }; -#define MIGRATE_PCPTYPES (MIGRATE_RECLAIMABLE+1) - #ifdef CONFIG_CMA # define is_migrate_cma(migratetype) unlikely((migratetype) == MIGRATE_CMA) #else @@ -334,6 +334,8 @@ struct zone { /* zone watermarks, access with *_wmark_pages(zone) macros */ unsigned long watermark[NR_WMARK]; + unsigned long nr_reserved_highatomic; + /* * We don't know if the memory that we're going to allocate will be freeable * or/and it will be released eventually, so to avoid totally wasting several diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 588812614377..55e9c56dfe54 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1615,6 +1615,101 @@ int find_suitable_fallback(struct free_area *area, unsigned int order, return -1; } +/* + * Reserve a pageblock for exclusive use of high-order atomic allocations if + * there are no empty page blocks that contain a page with a suitable order + */ +static void reserve_highatomic_pageblock(struct page *page, struct zone *zone, + unsigned int alloc_order) +{ + int mt; + unsigned long max_managed, flags; + + /* + * Limit the number reserved to 1 pageblock or roughly 1% of a zone. + * Check is race-prone but harmless. + */ + max_managed = (zone->managed_pages / 100) + pageblock_nr_pages; + if (zone->nr_reserved_highatomic >= max_managed) + return; + + spin_lock_irqsave(&zone->lock, flags); + + /* Recheck the nr_reserved_highatomic limit under the lock */ + if (zone->nr_reserved_highatomic >= max_managed) + goto out_unlock; + + /* Yoink! */ + mt = get_pageblock_migratetype(page); + if (mt != MIGRATE_HIGHATOMIC && + !is_migrate_isolate(mt) && !is_migrate_cma(mt)) { + zone->nr_reserved_highatomic += pageblock_nr_pages; + set_pageblock_migratetype(page, MIGRATE_HIGHATOMIC); + move_freepages_block(zone, page, MIGRATE_HIGHATOMIC); + } + +out_unlock: + spin_unlock_irqrestore(&zone->lock, flags); +} + +/* + * Used when an allocation is about to fail under memory pressure. This + * potentially hurts the reliability of high-order allocations when under + * intense memory pressure but failed atomic allocations should be easier + * to recover from than an OOM. + */ +static void unreserve_highatomic_pageblock(const struct alloc_context *ac) +{ + struct zonelist *zonelist = ac->zonelist; + unsigned long flags; + struct zoneref *z; + struct zone *zone; + struct page *page; + int order; + + for_each_zone_zonelist_nodemask(zone, z, zonelist, ac->high_zoneidx, + ac->nodemask) { + /* Preserve at least one pageblock */ + if (zone->nr_reserved_highatomic <= pageblock_nr_pages) + continue; + + spin_lock_irqsave(&zone->lock, flags); + for (order = 0; order < MAX_ORDER; order++) { + struct free_area *area = &(zone->free_area[order]); + + if (list_empty(&area->free_list[MIGRATE_HIGHATOMIC])) + continue; + + page = list_entry(area->free_list[MIGRATE_HIGHATOMIC].next, + struct page, lru); + + /* + * It should never happen but changes to locking could + * inadvertently allow a per-cpu drain to add pages + * to MIGRATE_HIGHATOMIC while unreserving so be safe + * and watch for underflows. + */ + zone->nr_reserved_highatomic -= min(pageblock_nr_pages, + zone->nr_reserved_highatomic); + + /* + * Convert to ac->migratetype and avoid the normal + * pageblock stealing heuristics. Minimally, the caller + * is doing the work and needs the pages. More + * importantly, if the block was always converted to + * MIGRATE_UNMOVABLE or another type then the number + * of pageblocks that cannot be completely freed + * may increase. + */ + set_pageblock_migratetype(page, ac->migratetype); + move_freepages_block(zone, page, ac->migratetype); + spin_unlock_irqrestore(&zone->lock, flags); + return; + } + spin_unlock_irqrestore(&zone->lock, flags); + } +} + /* Remove an element from the buddy allocator from the fallback list */ static inline struct page * __rmqueue_fallback(struct zone *zone, unsigned int order, int start_migratetype) @@ -1670,7 +1765,7 @@ __rmqueue_fallback(struct zone *zone, unsigned int order, int start_migratetype) * Call me with the zone->lock already held. */ static struct page *__rmqueue(struct zone *zone, unsigned int order, - int migratetype) + int migratetype, gfp_t gfp_flags) { struct page *page; @@ -1700,7 +1795,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order, spin_lock(&zone->lock); for (i = 0; i < count; ++i) { - struct page *page = __rmqueue(zone, order, migratetype); + struct page *page = __rmqueue(zone, order, migratetype, 0); if (unlikely(page == NULL)) break; @@ -2072,7 +2167,7 @@ int split_free_page(struct page *page) static inline struct page *buffered_rmqueue(struct zone *preferred_zone, struct zone *zone, unsigned int order, - gfp_t gfp_flags, int migratetype) + gfp_t gfp_flags, int alloc_flags, int migratetype) { unsigned long flags; struct page *page; @@ -2115,7 +2210,15 @@ struct page *buffered_rmqueue(struct zone *preferred_zone, WARN_ON_ONCE(order > 1); } spin_lock_irqsave(&zone->lock, flags); - page = __rmqueue(zone, order, migratetype); + + page = NULL; + if (alloc_flags & ALLOC_HARDER) { + page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC); + if (page) + trace_mm_page_alloc_zone_locked(page, order, migratetype); + } + if (!page) + page = __rmqueue(zone, order, migratetype, gfp_flags); spin_unlock(&zone->lock); if (!page) goto failed; @@ -2226,15 +2329,24 @@ static bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark, int classzone_idx, int alloc_flags, long free_pages) { - /* free_pages may go negative - that's OK */ long min = mark; int o; long free_cma = 0; + /* free_pages may go negative - that's OK */ free_pages -= (1 << order) - 1; + if (alloc_flags & ALLOC_HIGH) min -= min / 2; - if (alloc_flags & ALLOC_HARDER) + + /* + * If the caller does not have rights to ALLOC_HARDER then subtract + * the high-atomic reserves. This will over-estimate the size of the + * atomic reserve but it avoids a search. + */ + if (likely(!(alloc_flags & ALLOC_HARDER))) + free_pages -= z->nr_reserved_highatomic; + else min -= min / 4; #ifdef CONFIG_CMA @@ -2419,10 +2531,18 @@ zonelist_scan: try_this_zone: page = buffered_rmqueue(ac->preferred_zone, zone, order, - gfp_mask, ac->migratetype); + gfp_mask, alloc_flags, ac->migratetype); if (page) { if (prep_new_page(page, order, gfp_mask, alloc_flags)) goto try_this_zone; + + /* + * If this is a high-order atomic allocation then check + * if the pageblock should be reserved for the future + */ + if (unlikely(order && (alloc_flags & ALLOC_HARDER))) + reserve_highatomic_pageblock(page, zone, order); + return page; } } @@ -2695,9 +2815,11 @@ retry: /* * If an allocation failed after direct reclaim, it could be because - * pages are pinned on the per-cpu lists. Drain them and try again + * pages are pinned on the per-cpu lists or in high alloc reserves. + * Shrink them them and try again */ if (!page && !drained) { + unreserve_highatomic_pageblock(ac); drain_all_pages(NULL); drained = true; goto retry; diff --git a/mm/vmstat.c b/mm/vmstat.c index 5b289dcdcccf..879a2be23325 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -923,6 +923,7 @@ static char * const migratetype_names[MIGRATE_TYPES] = { "Unmovable", "Reclaimable", "Movable", + "HighAtomic", #ifdef CONFIG_CMA "CMA", #endif |