mm: compaction: update pageblock skip when first migration candidate is not at the...

isolate_migratepages_block should mark a pageblock as skip if scanning
started on an aligned pageblock boundary but it only updates the skip flag
if the first migration candidate is also aligned.  Tracing during a
compaction stress load (mmtests: workload-usemem-stress-numa-compact) that
many pageblocks are not marked skip causing excessive scanning of blocks
that had been recently checked.  Update pageblock skip based on
"valid_page" which is set if scanning started on a pageblock boundary.

[mgorman@techsingularity.net: fix handling of skip bit]
Link: https://lkml.kernel.org/r/20230602111622.swtxhn6lu2qwgrwq@techsingularity.net
Link: https://lkml.kernel.org/r/20230515113344.6869-4-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Tested-by: Raghavendra K T <raghavendra.kt@amd.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Chuyi Zhou <zhouchuyi@bytedance.com>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Maxim Levitsky <mlevitsk@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/compaction.c b/mm/compaction.c
index 009128d..02aa378 100644 (file)
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -392,18 +392,14 @@ void reset_isolation_suitable(pg_data_t *pgdat)
  * Sets the pageblock skip bit if it was clear. Note that this is a hint as
  * locks are not required for read/writers. Returns true if it was already set.
  */
-static bool test_and_set_skip(struct compact_control *cc, struct page *page,
-                                                       unsigned long pfn)
+static bool test_and_set_skip(struct compact_control *cc, struct page *page)
 {
        bool skip;
 
-       /* Do no update if skip hint is being ignored */
+       /* Do not update if skip hint is being ignored */
        if (cc->ignore_skip_hint)
                return false;
 
-       if (!pageblock_aligned(pfn))
-               return false;
-
        skip = get_pageblock_skip(page);
        if (!skip && !cc->no_set_skip_hint)
                set_pageblock_skip(page);
@@ -470,8 +466,7 @@ static void update_cached_migrate(struct compact_control *cc, unsigned long pfn)
 {
 }
 
-static bool test_and_set_skip(struct compact_control *cc, struct page *page,
-                                                       unsigned long pfn)
+static bool test_and_set_skip(struct compact_control *cc, struct page *page)
 {
        return false;
 }
@@ -1074,11 +1069,17 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 
                        lruvec_memcg_debug(lruvec, page_folio(page));
 
-                       /* Try get exclusive access under lock */
-                       if (!skip_updated) {
+                       /*
+                        * Try get exclusive access under lock. If marked for
+                        * skip, the scan is aborted unless the current context
+                        * is a rescan to reach the end of the pageblock.
+                        */
+                       if (!skip_updated && valid_page) {
                                skip_updated = true;
-                               if (test_and_set_skip(cc, page, low_pfn))
+                               if (test_and_set_skip(cc, valid_page) &&
+                                   !cc->finish_pageblock) {
                                        goto isolate_abort;
+                               }
                        }
 
                        /*