mm: delete NR_PAGES_SCANNED and pgdat_reclaimable()

NR_PAGES_SCANNED counts number of pages scanned since the last page free
event in the allocator.  This was used primarily to measure the
reclaimability of zones and nodes, and determine when reclaim should
give up on them.  In that role, it has been replaced in the preceding
patches by a different mechanism.

Being implemented as an efficient vmstat counter, it was automatically
exported to userspace as well.  It's however unlikely that anyone
outside the kernel is using this counter in any meaningful way.

Remove the counter and the unused pgdat_reclaimable().

Link: http://lkml.kernel.org/r/20170228214007.5621-8-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jia He <hejianet@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 19 deletions

diff --git a/mm/vmstat.c b/mm/vmstat.c
index baee70dafba8..c8d15051616b 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -954,7 +954,6 @@ const char * const vmstat_text[] = {
         "nr_unevictable",
         "nr_isolated_anon",
         "nr_isolated_file",
-        "nr_pages_scanned",
         "workingset_refault",
         "workingset_activate",
         "workingset_nodereclaim",
@@ -1378,7 +1377,6 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
                    "\n        min      %lu"
                    "\n        low      %lu"
                    "\n        high     %lu"
-                   "\n   node_scanned  %lu"
                    "\n        spanned  %lu"
                    "\n        present  %lu"
                    "\n        managed  %lu",
@@ -1386,7 +1384,6 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
                    min_wmark_pages(zone),
                    low_wmark_pages(zone),
                    high_wmark_pages(zone),
-                   node_page_state(zone->zone_pgdat, NR_PAGES_SCANNED),
                    zone->spanned_pages,
                    zone->present_pages,
                    zone->managed_pages);
@@ -1586,22 +1583,9 @@ int vmstat_refresh(struct ctl_table *table, int write,
         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
                 val = atomic_long_read(&vm_zone_stat[i]);
                 if (val < 0) {
-                        switch (i) {
-                        case NR_PAGES_SCANNED:
-                                /*
-                                 * This is often seen to go negative in
-                                 * recent kernels, but not to go permanently
-                                 * negative.  Whilst it would be nicer not to
-                                 * have exceptions, rooting them out would be
-                                 * another task, of rather low priority.
-                                 */
-                                break;
-                        default:
-                                pr_warn("%s: %s %ld\n",
-                                        __func__, vmstat_text[i], val);
-                                err = -EINVAL;
-                                break;
-                        }
+                        pr_warn("%s: %s %ld\n",
+                                __func__, vmstat_text[i], val);
+                        err = -EINVAL;
                 }
         }
         if (err)