FROMLIST: mm/vmscan.c: refactor shrink_node()

This patch refactors shrink_node() to improve readability for the
upcoming changes to mm/vmscan.c.

Link: https://lore.kernel.org/lkml/20220309021230.721028-4-yuzhao@google.com/
Signed-off-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Acked-by: Brian Geffon <bgeffon@google.com>
Acked-by: Jan Alexander Steffens (heftig) <heftig@archlinux.org>
Acked-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Acked-by: Steven Barrett <steven@liquorix.net>
Acked-by: Suleiman Souhlal <suleiman@google.com>
Tested-by: Daniel Byrne <djbyrne@mtu.edu>
Tested-by: Donald Carr <d@chaos-reins.com>
Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru>
Tested-by: Shuang Zhai <szhai2@cs.rochester.edu>
Tested-by: Sofia Trinh <sofia.trinh@edi.works>
Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Bug: 227651406
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Change-Id: I186f43f946de0d40d54883fb31114840fc749a57
[backport of the commit 8d47a32fa814aa5024253ba0c0a0e82c9ab2d1ae from android13-5.15 branch]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 38ff2cb..247d5c5 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2224,6 +2224,92 @@ enum scan_balance {
        SCAN_FILE,
 };
 
+static void prepare_scan_count(pg_data_t *pgdat, struct scan_control *sc)
+{
+       unsigned long file;
+       struct lruvec *target_lruvec;
+
+       target_lruvec = mem_cgroup_lruvec(sc->target_mem_cgroup, pgdat);
+
+       /*
+        * Target desirable inactive:active list ratios for the anon
+        * and file LRU lists.
+        */
+       if (!sc->force_deactivate) {
+               unsigned long refaults;
+
+               if (inactive_is_low(target_lruvec, LRU_INACTIVE_ANON))
+                       sc->may_deactivate |= DEACTIVATE_ANON;
+               else
+                       sc->may_deactivate &= ~DEACTIVATE_ANON;
+
+               /*
+                * When refaults are being observed, it means a new
+                * workingset is being established. Deactivate to get
+                * rid of any stale active pages quickly.
+                */
+               refaults = lruvec_page_state(target_lruvec,
+                                            WORKINGSET_ACTIVATE);
+               if (refaults != target_lruvec->refaults ||
+                   inactive_is_low(target_lruvec, LRU_INACTIVE_FILE))
+                       sc->may_deactivate |= DEACTIVATE_FILE;
+               else
+                       sc->may_deactivate &= ~DEACTIVATE_FILE;
+       } else
+               sc->may_deactivate = DEACTIVATE_ANON | DEACTIVATE_FILE;
+
+       /*
+        * If we have plenty of inactive file pages that aren't
+        * thrashing, try to reclaim those first before touching
+        * anonymous pages.
+        */
+       file = lruvec_page_state(target_lruvec, NR_INACTIVE_FILE);
+       if (file >> sc->priority && !(sc->may_deactivate & DEACTIVATE_FILE))
+               sc->cache_trim_mode = 1;
+       else
+               sc->cache_trim_mode = 0;
+
+       /*
+        * Prevent the reclaimer from falling into the cache trap: as
+        * cache pages start out inactive, every cache fault will tip
+        * the scan balance towards the file LRU.  And as the file LRU
+        * shrinks, so does the window for rotation from references.
+        * This means we have a runaway feedback loop where a tiny
+        * thrashing file LRU becomes infinitely more attractive than
+        * anon pages.  Try to detect this based on file LRU size.
+        */
+       if (!cgroup_reclaim(sc)) {
+               unsigned long total_high_wmark = 0;
+               unsigned long free, anon;
+               int z;
+
+               free = sum_zone_node_page_state(pgdat->node_id, NR_FREE_PAGES);
+               file = node_page_state(pgdat, NR_ACTIVE_FILE) +
+                          node_page_state(pgdat, NR_INACTIVE_FILE);
+
+               for (z = 0; z < MAX_NR_ZONES; z++) {
+                       struct zone *zone = &pgdat->node_zones[z];
+
+                       if (!managed_zone(zone))
+                               continue;
+
+                       total_high_wmark += high_wmark_pages(zone);
+               }
+
+               /*
+                * Consider anon: if that's low too, this isn't a
+                * runaway file reclaim problem, but rather just
+                * extreme pressure. Reclaim as per usual then.
+                */
+               anon = node_page_state(pgdat, NR_INACTIVE_ANON);
+
+               sc->file_is_tiny =
+                       file + free <= total_high_wmark &&
+                       !(sc->may_deactivate & DEACTIVATE_ANON) &&
+                       anon >> sc->priority;
+       }
+}
+
 /*
  * Determine how aggressively the anon and file LRU lists should be
  * scanned.  The relative value of each set of LRU lists is determined
@@ -2685,7 +2771,6 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
        unsigned long nr_reclaimed, nr_scanned;
        struct lruvec *target_lruvec;
        bool reclaimable = false;
-       unsigned long file;
 
        target_lruvec = mem_cgroup_lruvec(sc->target_mem_cgroup, pgdat);
 
@@ -2695,82 +2780,7 @@ again:
        nr_reclaimed = sc->nr_reclaimed;
        nr_scanned = sc->nr_scanned;
 
-       /*
-        * Target desirable inactive:active list ratios for the anon
-        * and file LRU lists.
-        */
-       if (!sc->force_deactivate) {
-               unsigned long refaults;
-
-               if (inactive_is_low(target_lruvec, LRU_INACTIVE_ANON))
-                       sc->may_deactivate |= DEACTIVATE_ANON;
-               else
-                       sc->may_deactivate &= ~DEACTIVATE_ANON;
-
-               /*
-                * When refaults are being observed, it means a new
-                * workingset is being established. Deactivate to get
-                * rid of any stale active pages quickly.
-                */
-               refaults = lruvec_page_state(target_lruvec,
-                                            WORKINGSET_ACTIVATE);
-               if (refaults != target_lruvec->refaults ||
-                   inactive_is_low(target_lruvec, LRU_INACTIVE_FILE))
-                       sc->may_deactivate |= DEACTIVATE_FILE;
-               else
-                       sc->may_deactivate &= ~DEACTIVATE_FILE;
-       } else
-               sc->may_deactivate = DEACTIVATE_ANON | DEACTIVATE_FILE;
-
-       /*
-        * If we have plenty of inactive file pages that aren't
-        * thrashing, try to reclaim those first before touching
-        * anonymous pages.
-        */
-       file = lruvec_page_state(target_lruvec, NR_INACTIVE_FILE);
-       if (file >> sc->priority && !(sc->may_deactivate & DEACTIVATE_FILE))
-               sc->cache_trim_mode = 1;
-       else
-               sc->cache_trim_mode = 0;
-
-       /*
-        * Prevent the reclaimer from falling into the cache trap: as
-        * cache pages start out inactive, every cache fault will tip
-        * the scan balance towards the file LRU.  And as the file LRU
-        * shrinks, so does the window for rotation from references.
-        * This means we have a runaway feedback loop where a tiny
-        * thrashing file LRU becomes infinitely more attractive than
-        * anon pages.  Try to detect this based on file LRU size.
-        */
-       if (!cgroup_reclaim(sc)) {
-               unsigned long total_high_wmark = 0;
-               unsigned long free, anon;
-               int z;
-
-               free = sum_zone_node_page_state(pgdat->node_id, NR_FREE_PAGES);
-               file = node_page_state(pgdat, NR_ACTIVE_FILE) +
-                          node_page_state(pgdat, NR_INACTIVE_FILE);
-
-               for (z = 0; z < MAX_NR_ZONES; z++) {
-                       struct zone *zone = &pgdat->node_zones[z];
-                       if (!managed_zone(zone))
-                               continue;
-
-                       total_high_wmark += high_wmark_pages(zone);
-               }
-
-               /*
-                * Consider anon: if that's low too, this isn't a
-                * runaway file reclaim problem, but rather just
-                * extreme pressure. Reclaim as per usual then.
-                */
-               anon = node_page_state(pgdat, NR_INACTIVE_ANON);
-
-               sc->file_is_tiny =
-                       file + free <= total_high_wmark &&
-                       !(sc->may_deactivate & DEACTIVATE_ANON) &&
-                       anon >> sc->priority;
-       }
+       prepare_scan_count(pgdat, sc);
 
        shrink_node_memcgs(pgdat, sc);