mm, compaction: embed migration mode in compact_control

We're going to want to manipulate the migration mode for compaction in the
page allocator, and currently compact_control's sync field is only a bool.

Currently, we only do MIGRATE_ASYNC or MIGRATE_SYNC_LIGHT compaction
depending on the value of this bool.  Convert the bool to enum
migrate_mode and pass the migration mode in directly.  Later, we'll want
to avoid MIGRATE_SYNC_LIGHT for thp allocations in the pagefault patch to
avoid unnecessary latency.

This also alters compaction triggered from sysfs, either for the entire
system or for a node, to force MIGRATE_SYNC.

[akpm@linux-foundation.org: fix build]
[iamjoonsoo.kim@lge.com: use MIGRATE_SYNC in alloc_contig_range()]
Signed-off-by: David Rientjes <rientjes@google.com>
Suggested-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 19 insertions, 17 deletions

diff --git a/mm/compaction.c b/mm/compaction.c
index 70c0f8cda33f..217a6ad9a20e 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -161,7 +161,8 @@ static void update_pageblock_skip(struct compact_control *cc,
                         return;
                 if (pfn > zone->compact_cached_migrate_pfn[0])
                         zone->compact_cached_migrate_pfn[0] = pfn;
-                if (cc->sync && pfn > zone->compact_cached_migrate_pfn[1])
+                if (cc->mode != MIGRATE_ASYNC &&
+                    pfn > zone->compact_cached_migrate_pfn[1])
                         zone->compact_cached_migrate_pfn[1] = pfn;
         } else {
                 if (cc->finished_update_free)
@@ -208,7 +209,7 @@ static bool compact_checklock_irqsave(spinlock_t *lock, unsigned long *flags,
                 }
 
                 /* async aborts if taking too long or contended */
-                if (!cc->sync) {
+                if (cc->mode == MIGRATE_ASYNC) {
                         cc->contended = true;
                         return false;
                 }
@@ -473,7 +474,8 @@ isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
         bool locked = false;
         struct page *page = NULL, *valid_page = NULL;
         bool set_unsuitable = true;
-        const isolate_mode_t mode = (!cc->sync ? ISOLATE_ASYNC_MIGRATE : 0) |
+        const isolate_mode_t mode = (cc->mode == MIGRATE_ASYNC ?
+                                        ISOLATE_ASYNC_MIGRATE : 0) |
                                     (unevictable ? ISOLATE_UNEVICTABLE : 0);
 
         /*
@@ -483,7 +485,7 @@ isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
          */
         while (unlikely(too_many_isolated(zone))) {
                 /* async migration should just abort */
-                if (!cc->sync)
+                if (cc->mode == MIGRATE_ASYNC)
                         return 0;
 
                 congestion_wait(BLK_RW_ASYNC, HZ/10);
@@ -548,7 +550,8 @@ isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
                          * the minimum amount of work satisfies the allocation
                          */
                         mt = get_pageblock_migratetype(page);
-                        if (!cc->sync && !migrate_async_suitable(mt)) {
+                        if (cc->mode == MIGRATE_ASYNC &&
+                            !migrate_async_suitable(mt)) {
                                 set_unsuitable = false;
                                 goto next_pageblock;
                         }
@@ -981,6 +984,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
         int ret;
         unsigned long start_pfn = zone->zone_start_pfn;
         unsigned long end_pfn = zone_end_pfn(zone);
+        const bool sync = cc->mode != MIGRATE_ASYNC;
 
         ret = compaction_suitable(zone, cc->order);
         switch (ret) {
@@ -1006,7 +1010,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
          * information on where the scanners should start but check that it
          * is initialised by ensuring the values are within zone boundaries.
          */
-        cc->migrate_pfn = zone->compact_cached_migrate_pfn[cc->sync];
+        cc->migrate_pfn = zone->compact_cached_migrate_pfn[sync];
         cc->free_pfn = zone->compact_cached_free_pfn;
         if (cc->free_pfn < start_pfn || cc->free_pfn > end_pfn) {
                 cc->free_pfn = end_pfn & ~(pageblock_nr_pages-1);
@@ -1040,8 +1044,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
 
                 nr_migrate = cc->nr_migratepages;
                 err = migrate_pages(&cc->migratepages, compaction_alloc,
-                                compaction_free, (unsigned long)cc,
-                                cc->sync ? MIGRATE_SYNC_LIGHT : MIGRATE_ASYNC,
+                                compaction_free, (unsigned long)cc, cc->mode,
                                 MR_COMPACTION);
                 update_nr_listpages(cc);
                 nr_remaining = cc->nr_migratepages;
@@ -1074,9 +1077,8 @@ out:
         return ret;
 }
 
-static unsigned long compact_zone_order(struct zone *zone,
-                                 int order, gfp_t gfp_mask,
-                                 bool sync, bool *contended)
+static unsigned long compact_zone_order(struct zone *zone, int order,
+                gfp_t gfp_mask, enum migrate_mode mode, bool *contended)
 {
         unsigned long ret;
         struct compact_control cc = {
@@ -1085,7 +1087,7 @@ static unsigned long compact_zone_order(struct zone *zone,
                 .order = order,
                 .migratetype = allocflags_to_migratetype(gfp_mask),
                 .zone = zone,
-                .sync = sync,
+                .mode = mode,
         };
         INIT_LIST_HEAD(&cc.freepages);
         INIT_LIST_HEAD(&cc.migratepages);
@@ -1107,7 +1109,7 @@ int sysctl_extfrag_threshold = 500;
  * @order: The order of the current allocation
  * @gfp_mask: The GFP mask of the current allocation
  * @nodemask: The allowed nodes to allocate from
- * @sync: Whether migration is synchronous or not
+ * @mode: The migration mode for async, sync light, or sync migration
  * @contended: Return value that is true if compaction was aborted due to lock contention
  * @page: Optionally capture a free page of the requested order during compaction
  *
@@ -1115,7 +1117,7 @@ int sysctl_extfrag_threshold = 500;
  */
 unsigned long try_to_compact_pages(struct zonelist *zonelist,
                         int order, gfp_t gfp_mask, nodemask_t *nodemask,
-                        bool sync, bool *contended)
+                        enum migrate_mode mode, bool *contended)
 {
         enum zone_type high_zoneidx = gfp_zone(gfp_mask);
         int may_enter_fs = gfp_mask & __GFP_FS;
@@ -1140,7 +1142,7 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist,
                                                                 nodemask) {
                 int status;
 
-                status = compact_zone_order(zone, order, gfp_mask, sync,
+                status = compact_zone_order(zone, order, gfp_mask, mode,
                                                 contended);
                 rc = max(status, rc);
 
@@ -1190,7 +1192,7 @@ void compact_pgdat(pg_data_t *pgdat, int order)
 {
         struct compact_control cc = {
                 .order = order,
-                .sync = false,
+                .mode = MIGRATE_ASYNC,
         };
 
         if (!order)
@@ -1203,7 +1205,7 @@ static void compact_node(int nid)
 {
         struct compact_control cc = {
                 .order = -1,
-                .sync = true,
+                .mode = MIGRATE_SYNC,
                 .ignore_skip_hint = true,
         };