mm/vmscan: store "priority" in struct scan_control

In memory reclaim some function have too many arguments - "priority" is
one of them.  It can be stored in struct scan_control - we construct them
on the same level.  Instead of an open coded loop we set the initial
sc.priority, and do_try_to_free_pages() decreases it down to zero.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.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, 61 insertions, 56 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 0e2131deb2d3..77905eb3d8ad 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -78,6 +78,9 @@ struct scan_control {
 
         int order;
 
+        /* Scan (total_size >> priority) pages at once */
+        int priority;
+
         /*
          * The memory cgroup that hit its limit and as a result is the
          * primary target of this reclaim invocation.
@@ -687,7 +690,6 @@ static enum page_references page_check_references(struct page *page,
 static unsigned long shrink_page_list(struct list_head *page_list,
                                       struct mem_cgroup_zone *mz,
                                       struct scan_control *sc,
-                                      int priority,
                                       unsigned long *ret_nr_dirty,
                                       unsigned long *ret_nr_writeback)
 {
@@ -790,7 +792,8 @@ static unsigned long shrink_page_list(struct list_head *page_list,
                          * unless under significant pressure.
                          */
                         if (page_is_file_cache(page) &&
-                                        (!current_is_kswapd() || priority >= DEF_PRIORITY - 2)) {
+                                        (!current_is_kswapd() ||
+                                         sc->priority >= DEF_PRIORITY - 2)) {
                                 /*
                                  * Immediately reclaim when written back.
                                  * Similar in principal to deactivate_page()
@@ -1257,7 +1260,7 @@ update_isolated_counts(struct mem_cgroup_zone *mz,
  */
 static noinline_for_stack unsigned long
 shrink_inactive_list(unsigned long nr_to_scan, struct mem_cgroup_zone *mz,
-                     struct scan_control *sc, int priority, enum lru_list lru)
+                     struct scan_control *sc, enum lru_list lru)
 {
         LIST_HEAD(page_list);
         unsigned long nr_scanned;
@@ -1307,7 +1310,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct mem_cgroup_zone *mz,
 
         update_isolated_counts(mz, &page_list, &nr_anon, &nr_file);
 
-        nr_reclaimed = shrink_page_list(&page_list, mz, sc, priority,
+        nr_reclaimed = shrink_page_list(&page_list, mz, sc,
                                                 &nr_dirty, &nr_writeback);
 
         spin_lock_irq(&zone->lru_lock);
@@ -1356,13 +1359,14 @@ shrink_inactive_list(unsigned long nr_to_scan, struct mem_cgroup_zone *mz,
          * DEF_PRIORITY-6 For SWAP_CLUSTER_MAX isolated pages, throttle if any
          *                     isolated page is PageWriteback
          */
-        if (nr_writeback && nr_writeback >= (nr_taken >> (DEF_PRIORITY-priority)))
+        if (nr_writeback && nr_writeback >=
+                        (nr_taken >> (DEF_PRIORITY - sc->priority)))
                 wait_iff_congested(zone, BLK_RW_ASYNC, HZ/10);
 
         trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id,
                 zone_idx(zone),
                 nr_scanned, nr_reclaimed,
-                priority,
+                sc->priority,
                 trace_shrink_flags(file));
         return nr_reclaimed;
 }
@@ -1426,7 +1430,7 @@ static void move_active_pages_to_lru(struct zone *zone,
 static void shrink_active_list(unsigned long nr_to_scan,
                                struct mem_cgroup_zone *mz,
                                struct scan_control *sc,
-                               int priority, enum lru_list lru)
+                               enum lru_list lru)
 {
         unsigned long nr_taken;
         unsigned long nr_scanned;
@@ -1609,17 +1613,17 @@ static int inactive_list_is_low(struct mem_cgroup_zone *mz, int file)
 
 static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
                                  struct mem_cgroup_zone *mz,
-                                 struct scan_control *sc, int priority)
+                                 struct scan_control *sc)
 {
         int file = is_file_lru(lru);
 
         if (is_active_lru(lru)) {
                 if (inactive_list_is_low(mz, file))
-                        shrink_active_list(nr_to_scan, mz, sc, priority, lru);
+                        shrink_active_list(nr_to_scan, mz, sc, lru);
                 return 0;
         }
 
-        return shrink_inactive_list(nr_to_scan, mz, sc, priority, lru);
+        return shrink_inactive_list(nr_to_scan, mz, sc, lru);
 }
 
 static int vmscan_swappiness(struct scan_control *sc)
@@ -1638,7 +1642,7 @@ static int vmscan_swappiness(struct scan_control *sc)
  * nr[0] = anon pages to scan; nr[1] = file pages to scan
  */
 static void get_scan_count(struct mem_cgroup_zone *mz, struct scan_control *sc,
-                           unsigned long *nr, int priority)
+                           unsigned long *nr)
 {
         unsigned long anon, file, free;
         unsigned long anon_prio, file_prio;
@@ -1740,8 +1744,8 @@ out:
                 unsigned long scan;
 
                 scan = zone_nr_lru_pages(mz, lru);
-                if (priority || noswap || !vmscan_swappiness(sc)) {
-                        scan >>= priority;
+                if (sc->priority || noswap || !vmscan_swappiness(sc)) {
+                        scan >>= sc->priority;
                         if (!scan && force_scan)
                                 scan = SWAP_CLUSTER_MAX;
                         scan = div64_u64(scan * fraction[file], denominator);
@@ -1751,11 +1755,11 @@ out:
 }
 
 /* Use reclaim/compaction for costly allocs or under memory pressure */
-static bool in_reclaim_compaction(int priority, struct scan_control *sc)
+static bool in_reclaim_compaction(struct scan_control *sc)
 {
         if (COMPACTION_BUILD && sc->order &&
                         (sc->order > PAGE_ALLOC_COSTLY_ORDER ||
-                         priority < DEF_PRIORITY - 2))
+                         sc->priority < DEF_PRIORITY - 2))
                 return true;
 
         return false;
@@ -1771,14 +1775,13 @@ static bool in_reclaim_compaction(int priority, struct scan_control *sc)
 static inline bool should_continue_reclaim(struct mem_cgroup_zone *mz,
                                         unsigned long nr_reclaimed,
                                         unsigned long nr_scanned,
-                                        int priority,
                                         struct scan_control *sc)
 {
         unsigned long pages_for_compaction;
         unsigned long inactive_lru_pages;
 
         /* If not in reclaim/compaction mode, stop */
-        if (!in_reclaim_compaction(priority, sc))
+        if (!in_reclaim_compaction(sc))
                 return false;
 
         /* Consider stopping depending on scan and reclaim activity */
@@ -1829,7 +1832,7 @@ static inline bool should_continue_reclaim(struct mem_cgroup_zone *mz,
 /*
  * This is a basic per-zone page freer.  Used by both kswapd and direct reclaim.
  */
-static void shrink_mem_cgroup_zone(int priority, struct mem_cgroup_zone *mz,
+static void shrink_mem_cgroup_zone(struct mem_cgroup_zone *mz,
                                    struct scan_control *sc)
 {
         unsigned long nr[NR_LRU_LISTS];
@@ -1842,7 +1845,7 @@ static void shrink_mem_cgroup_zone(int priority, struct mem_cgroup_zone *mz,
 restart:
         nr_reclaimed = 0;
         nr_scanned = sc->nr_scanned;
-        get_scan_count(mz, sc, nr, priority);
+        get_scan_count(mz, sc, nr);
 
         blk_start_plug(&plug);
         while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
@@ -1854,7 +1857,7 @@ restart:
                                 nr[lru] -= nr_to_scan;
 
                                 nr_reclaimed += shrink_list(lru, nr_to_scan,
-                                                            mz, sc, priority);
+                                                            mz, sc);
                         }
                 }
                 /*
@@ -1865,7 +1868,8 @@ restart:
                  * with multiple processes reclaiming pages, the total
                  * freeing target can get unreasonably large.
                  */
-                if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY)
+                if (nr_reclaimed >= nr_to_reclaim &&
+                    sc->priority < DEF_PRIORITY)
                         break;
         }
         blk_finish_plug(&plug);
@@ -1877,24 +1881,22 @@ restart:
          */
         if (inactive_anon_is_low(mz))
                 shrink_active_list(SWAP_CLUSTER_MAX, mz,
-                                   sc, priority, LRU_ACTIVE_ANON);
+                                   sc, LRU_ACTIVE_ANON);
 
         /* reclaim/compaction might need reclaim to continue */
         if (should_continue_reclaim(mz, nr_reclaimed,
-                                        sc->nr_scanned - nr_scanned,
-                                        priority, sc))
+                                    sc->nr_scanned - nr_scanned, sc))
                 goto restart;
 
         throttle_vm_writeout(sc->gfp_mask);
 }
 
-static void shrink_zone(int priority, struct zone *zone,
-                        struct scan_control *sc)
+static void shrink_zone(struct zone *zone, struct scan_control *sc)
 {
         struct mem_cgroup *root = sc->target_mem_cgroup;
         struct mem_cgroup_reclaim_cookie reclaim = {
                 .zone = zone,
-                .priority = priority,
+                .priority = sc->priority,
         };
         struct mem_cgroup *memcg;
 
@@ -1905,7 +1907,7 @@ static void shrink_zone(int priority, struct zone *zone,
                         .zone = zone,
                 };
 
-                shrink_mem_cgroup_zone(priority, &mz, sc);
+                shrink_mem_cgroup_zone(&mz, sc);
                 /*
                  * Limit reclaim has historically picked one memcg and
                  * scanned it with decreasing priority levels until
@@ -1981,8 +1983,7 @@ static inline bool compaction_ready(struct zone *zone, struct scan_control *sc)
  * the caller that it should consider retrying the allocation instead of
  * further reclaim.
  */
-static bool shrink_zones(int priority, struct zonelist *zonelist,
-                                        struct scan_control *sc)
+static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
 {
         struct zoneref *z;
         struct zone *zone;
@@ -2009,7 +2010,8 @@ static bool shrink_zones(int priority, struct zonelist *zonelist,
                 if (global_reclaim(sc)) {
                         if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
                                 continue;
-                        if (zone->all_unreclaimable && priority != DEF_PRIORITY)
+                        if (zone->all_unreclaimable &&
+                                        sc->priority != DEF_PRIORITY)
                                 continue;       /* Let kswapd poll it */
                         if (COMPACTION_BUILD) {
                                 /*
@@ -2041,7 +2043,7 @@ static bool shrink_zones(int priority, struct zonelist *zonelist,
                         /* need some check for avoid more shrink_zone() */
                 }
 
-                shrink_zone(priority, zone, sc);
+                shrink_zone(zone, sc);
         }
 
         return aborted_reclaim;
@@ -2092,7 +2094,6 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
                                         struct scan_control *sc,
                                         struct shrink_control *shrink)
 {
-        int priority;
         unsigned long total_scanned = 0;
         struct reclaim_state *reclaim_state = current->reclaim_state;
         struct zoneref *z;
@@ -2105,9 +2106,9 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
         if (global_reclaim(sc))
                 count_vm_event(ALLOCSTALL);
 
-        for (priority = DEF_PRIORITY; priority >= 0; priority--) {
+        do {
                 sc->nr_scanned = 0;
-                aborted_reclaim = shrink_zones(priority, zonelist, sc);
+                aborted_reclaim = shrink_zones(zonelist, sc);
 
                 /*
                  * Don't shrink slabs when reclaiming memory from
@@ -2149,7 +2150,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
 
                 /* Take a nap, wait for some writeback to complete */
                 if (!sc->hibernation_mode && sc->nr_scanned &&
-                    priority < DEF_PRIORITY - 2) {
+                    sc->priority < DEF_PRIORITY - 2) {
                         struct zone *preferred_zone;
 
                         first_zones_zonelist(zonelist, gfp_zone(sc->gfp_mask),
@@ -2157,7 +2158,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
                                                 &preferred_zone);
                         wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/10);
                 }
-        }
+        } while (--sc->priority >= 0);
 
 out:
         delayacct_freepages_end();
@@ -2195,6 +2196,7 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
                 .may_unmap = 1,
                 .may_swap = 1,
                 .order = order,
+                .priority = DEF_PRIORITY,
                 .target_mem_cgroup = NULL,
                 .nodemask = nodemask,
         };
@@ -2227,6 +2229,7 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *memcg,
                 .may_unmap = 1,
                 .may_swap = !noswap,
                 .order = 0,
+                .priority = 0,
                 .target_mem_cgroup = memcg,
         };
         struct mem_cgroup_zone mz = {
@@ -2237,7 +2240,7 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *memcg,
         sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
                         (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
 
-        trace_mm_vmscan_memcg_softlimit_reclaim_begin(0,
+        trace_mm_vmscan_memcg_softlimit_reclaim_begin(sc.order,
                                                       sc.may_writepage,
                                                       sc.gfp_mask);
 
@@ -2248,7 +2251,7 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *memcg,
          * will pick up pages from other mem cgroup's as well. We hack
          * the priority and make it zero.
          */
-        shrink_mem_cgroup_zone(0, &mz, &sc);
+        shrink_mem_cgroup_zone(&mz, &sc);
 
         trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
 
@@ -2269,6 +2272,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
                 .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) |
@@ -2299,8 +2303,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
 }
 #endif
 
-static void age_active_anon(struct zone *zone, struct scan_control *sc,
-                            int priority)
+static void age_active_anon(struct zone *zone, struct scan_control *sc)
 {
         struct mem_cgroup *memcg;
 
@@ -2316,7 +2319,7 @@ static void age_active_anon(struct zone *zone, struct scan_control *sc,
 
                 if (inactive_anon_is_low(&mz))
                         shrink_active_list(SWAP_CLUSTER_MAX, &mz,
-                                           sc, priority, LRU_ACTIVE_ANON);
+                                           sc, LRU_ACTIVE_ANON);
 
                 memcg = mem_cgroup_iter(NULL, memcg, NULL);
         } while (memcg);
@@ -2425,7 +2428,6 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
 {
         int all_zones_ok;
         unsigned long balanced;
-        int priority;
         int i;
         int end_zone = 0;       /* Inclusive.  0 = ZONE_DMA */
         unsigned long total_scanned;
@@ -2449,11 +2451,12 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
         };
 loop_again:
         total_scanned = 0;
+        sc.priority = DEF_PRIORITY;
         sc.nr_reclaimed = 0;
         sc.may_writepage = !laptop_mode;
         count_vm_event(PAGEOUTRUN);
 
-        for (priority = DEF_PRIORITY; priority >= 0; priority--) {
+        do {
                 unsigned long lru_pages = 0;
                 int has_under_min_watermark_zone = 0;
 
@@ -2470,14 +2473,15 @@ loop_again:
                         if (!populated_zone(zone))
                                 continue;
 
-                        if (zone->all_unreclaimable && priority != DEF_PRIORITY)
+                        if (zone->all_unreclaimable &&
+                            sc.priority != DEF_PRIORITY)
                                 continue;
 
                         /*
                          * Do some background aging of the anon list, to give
                          * pages a chance to be referenced before reclaiming.
                          */
-                        age_active_anon(zone, &sc, priority);
+                        age_active_anon(zone, &sc);
 
                         /*
                          * If the number of buffer_heads in the machine
@@ -2525,7 +2529,8 @@ loop_again:
                         if (!populated_zone(zone))
                                 continue;
 
-                        if (zone->all_unreclaimable && priority != DEF_PRIORITY)
+                        if (zone->all_unreclaimable &&
+                            sc.priority != DEF_PRIORITY)
                                 continue;
 
                         sc.nr_scanned = 0;
@@ -2569,7 +2574,7 @@ loop_again:
                                     !zone_watermark_ok_safe(zone, testorder,
                                         high_wmark_pages(zone) + balance_gap,
                                         end_zone, 0)) {
-                                shrink_zone(priority, zone, &sc);
+                                shrink_zone(zone, &sc);
 
                                 reclaim_state->reclaimed_slab = 0;
                                 nr_slab = shrink_slab(&shrink, sc.nr_scanned, lru_pages);
@@ -2626,7 +2631,7 @@ loop_again:
                  * OK, kswapd is getting into trouble.  Take a nap, then take
                  * another pass across the zones.
                  */
-                if (total_scanned && (priority < DEF_PRIORITY - 2)) {
+                if (total_scanned && (sc.priority < DEF_PRIORITY - 2)) {
                         if (has_under_min_watermark_zone)
                                 count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT);
                         else
@@ -2641,7 +2646,7 @@ loop_again:
                  */
                 if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX)
                         break;
-        }
+        } while (--sc.priority >= 0);
 out:
 
         /*
@@ -2691,7 +2696,8 @@ out:
                         if (!populated_zone(zone))
                                 continue;
 
-                        if (zone->all_unreclaimable && priority != DEF_PRIORITY)
+                        if (zone->all_unreclaimable &&
+                            sc.priority != DEF_PRIORITY)
                                 continue;
 
                         /* Would compaction fail due to lack of free memory? */
@@ -2958,6 +2964,7 @@ unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
                 .nr_to_reclaim = nr_to_reclaim,
                 .hibernation_mode = 1,
                 .order = 0,
+                .priority = DEF_PRIORITY,
         };
         struct shrink_control shrink = {
                 .gfp_mask = sc.gfp_mask,
@@ -3135,7 +3142,6 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
         const unsigned long nr_pages = 1 << order;
         struct task_struct *p = current;
         struct reclaim_state reclaim_state;
-        int priority;
         struct scan_control sc = {
                 .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
                 .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP),
@@ -3144,6 +3150,7 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
                                        SWAP_CLUSTER_MAX),
                 .gfp_mask = gfp_mask,
                 .order = order,
+                .priority = ZONE_RECLAIM_PRIORITY,
         };
         struct shrink_control shrink = {
                 .gfp_mask = sc.gfp_mask,
@@ -3166,11 +3173,9 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
                  * Free memory by calling shrink zone with increasing
                  * priorities until we have enough memory freed.
                  */
-                priority = ZONE_RECLAIM_PRIORITY;
                 do {
-                        shrink_zone(priority, zone, &sc);
-                        priority--;
-                } while (priority >= 0 && sc.nr_reclaimed < nr_pages);
+                        shrink_zone(zone, &sc);
+                } while (sc.nr_reclaimed < nr_pages && --sc.priority >= 0);
         }
 
         nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE);