linux-kernel - [PATCH] mm: page_alloc: dump migrate-failed pages only at -EBUSY

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Date:   Wed, 19 May 2021 14:33:41 -0700
From:   Minchan Kim <minchan@...nel.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Suren Baghdasaryan <surenb@...gle.com>,
        John Dias <joaodias@...gle.com>,
        Michal Hocko <mhocko@...e.com>,
        David Hildenbrand <david@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-mm <linux-mm@...ck.org>, Minchan Kim <minchan@...nel.org>
Subject: [PATCH] mm: page_alloc: dump migrate-failed pages only at -EBUSY

alloc_contig_dump_pages aims for helping debugging page migration
failure by page refcount mismatch or something else of page itself
from migration handler function. However, in -ENOMEM case, there is
nothing to get clue from page descriptor information so just
dump pages only when -EBUSY happens.

Signed-off-by: Minchan Kim <minchan@...nel.org>
---
 mm/page_alloc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3100fcb08500..c0a2971dc755 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8760,7 +8760,8 @@ 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;
 	}
-- 
2.31.1.751.gd2f1c929bd-goog