mm: vmscan: clean up struct scan_control

Reorder the members by input and output, then turn the individual
integers for may_writepage, may_unmap, may_swap, compaction_ready,
hibernation_mode into bit fields to save stack space:

  +72/-296 -224
  kswapd                                       104     176     +72
  try_to_free_pages                             80      56     -24
  try_to_free_mem_cgroup_pages                  80      56     -24
  shrink_all_memory                             88      64     -24
  reclaim_clean_pages_from_list                168     144     -24
  mem_cgroup_shrink_node_zone                  104      80     -24
  __zone_reclaim                               176     152     -24
  balance_pgdat                                152       -    -152

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: Mel Gorman <mgorman@suse.de>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 46 insertions, 53 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index c28b8981e56a..81dd858b9d17 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -59,35 +59,20 @@
 #include <trace/events/vmscan.h>
 
 struct scan_control {
-        /* Incremented by the number of inactive pages that were scanned */
-        unsigned long nr_scanned;
-
-        /* Number of pages freed so far during a call to shrink_zones() */
-        unsigned long nr_reclaimed;
-
-        /* One of the zones is ready for compaction */
-        int compaction_ready;
-
         /* How many pages shrink_list() should reclaim */
         unsigned long nr_to_reclaim;
 
-        unsigned long hibernation_mode;
-
         /* This context's GFP mask */
         gfp_t gfp_mask;
 
-        int may_writepage;
-
-        /* Can mapped pages be reclaimed? */
-        int may_unmap;
-
-        /* Can pages be swapped as part of reclaim? */
-        int may_swap;
-
+        /* Allocation order */
         int order;
 
-        /* Scan (total_size >> priority) pages at once */
-        int priority;
+        /*
+         * Nodemask of nodes allowed by the caller. If NULL, all nodes
+         * are scanned.
+         */
+        nodemask_t      *nodemask;
 
         /*
          * The memory cgroup that hit its limit and as a result is the
@@ -95,11 +80,27 @@ struct scan_control {
          */
         struct mem_cgroup *target_mem_cgroup;
 
-        /*
-         * Nodemask of nodes allowed by the caller. If NULL, all nodes
-         * are scanned.
-         */
-        nodemask_t      *nodemask;
+        /* Scan (total_size >> priority) pages at once */
+        int priority;
+
+        unsigned int may_writepage:1;
+
+        /* Can mapped pages be reclaimed? */
+        unsigned int may_unmap:1;
+
+        /* Can pages be swapped as part of reclaim? */
+        unsigned int may_swap:1;
+
+        unsigned int hibernation_mode:1;
+
+        /* One of the zones is ready for compaction */
+        unsigned int compaction_ready:1;
+
+        /* Incremented by the number of inactive pages that were scanned */
+        unsigned long nr_scanned;
+
+        /* Number of pages freed so far during a call to shrink_zones() */
+        unsigned long nr_reclaimed;
 };
 
 #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
@@ -2668,15 +2669,14 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 {
         unsigned long nr_reclaimed;
         struct scan_control sc = {
+                .nr_to_reclaim = SWAP_CLUSTER_MAX,
                 .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)),
+                .order = order,
+                .nodemask = nodemask,
+                .priority = DEF_PRIORITY,
                 .may_writepage = !laptop_mode,
-                .nr_to_reclaim = SWAP_CLUSTER_MAX,
                 .may_unmap = 1,
                 .may_swap = 1,
-                .order = order,
-                .priority = DEF_PRIORITY,
-                .target_mem_cgroup = NULL,
-                .nodemask = nodemask,
         };
 
         /*
@@ -2706,14 +2706,11 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *memcg,
                                                 unsigned long *nr_scanned)
 {
         struct scan_control sc = {
-                .nr_scanned = 0,
                 .nr_to_reclaim = SWAP_CLUSTER_MAX,
+                .target_mem_cgroup = memcg,
                 .may_writepage = !laptop_mode,
                 .may_unmap = 1,
                 .may_swap = !noswap,
-                .order = 0,
-                .priority = 0,
-                .target_mem_cgroup = memcg,
         };
         struct lruvec *lruvec = mem_cgroup_zone_lruvec(zone, memcg);
         int swappiness = mem_cgroup_swappiness(memcg);
@@ -2748,16 +2745,14 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
         unsigned long nr_reclaimed;
         int nid;
         struct scan_control sc = {
-                .may_writepage = !laptop_mode,
-                .may_unmap = 1,
-                .may_swap = !noswap,
                 .nr_to_reclaim = SWAP_CLUSTER_MAX,
-                .order = 0,
-                .priority = DEF_PRIORITY,
-                .target_mem_cgroup = memcg,
-                .nodemask = NULL, /* we don't care the placement */
                 .gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
                                 (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK),
+                .target_mem_cgroup = memcg,
+                .priority = DEF_PRIORITY,
+                .may_writepage = !laptop_mode,
+                .may_unmap = 1,
+                .may_swap = !noswap,
         };
 
         /*
@@ -3015,12 +3010,11 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
         unsigned long nr_soft_scanned;
         struct scan_control sc = {
                 .gfp_mask = GFP_KERNEL,
+                .order = order,
                 .priority = DEF_PRIORITY,
+                .may_writepage = !laptop_mode,
                 .may_unmap = 1,
                 .may_swap = 1,
-                .may_writepage = !laptop_mode,
-                .order = order,
-                .target_mem_cgroup = NULL,
         };
         count_vm_event(PAGEOUTRUN);
 
@@ -3401,14 +3395,13 @@ unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
 {
         struct reclaim_state reclaim_state;
         struct scan_control sc = {
+                .nr_to_reclaim = nr_to_reclaim,
                 .gfp_mask = GFP_HIGHUSER_MOVABLE,
-                .may_swap = 1,
-                .may_unmap = 1,
+                .priority = DEF_PRIORITY,
                 .may_writepage = 1,
-                .nr_to_reclaim = nr_to_reclaim,
+                .may_unmap = 1,
+                .may_swap = 1,
                 .hibernation_mode = 1,
-                .order = 0,
-                .priority = DEF_PRIORITY,
         };
         struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
         struct task_struct *p = current;
@@ -3588,13 +3581,13 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
         struct task_struct *p = current;
         struct reclaim_state reclaim_state;
         struct scan_control sc = {
-                .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
-                .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP),
-                .may_swap = 1,
                 .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
                 .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)),
                 .order = order,
                 .priority = ZONE_RECLAIM_PRIORITY,
+                .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
+                .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP),
+                .may_swap = 1,
         };
         struct shrink_control shrink = {
                 .gfp_mask = sc.gfp_mask,