mm: page_alloc: dump migrate-failed pages only at -EBUSY

alloc_contig_dump_pages() aims for helping debugging page migration
failure by elevated page refcount compared to expected_count.  (for the
detail, please look at migrate_page_move_mapping)

However, -ENOMEM is just the case that system is under memory pressure
state, not relevant with page refcount at all.  Thus, the dumping page
list is not helpful for the debugging point of view.

Link: https://lkml.kernel.org/r/YKa2Wyo9xqIErpfa@google.com
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: John Dias <joaodias@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 37ce0c2f3bae87a61700df5b917ba7dda82f79e7..941a75b9fb5abe82506376c3eb8569e30058a1cb 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8800,7 +8800,8 @@ static int __alloc_contig_migrate_range(struct compact_control *cc,
 
        lru_cache_enable();
        if (ret < 0) {
-               alloc_contig_dump_pages(&cc->migratepages);
+               if (ret == -EBUSY)
+                       alloc_contig_dump_pages(&cc->migratepages);
                putback_movable_pages(&cc->migratepages);
                return ret;
        }