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From: Oscar Salvador <osalvador@suse.de>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	David Hildenbrand <david@redhat.com>,
	Michal Hocko <mhocko@kernel.org>,
	Muchun Song <songmuchun@bytedance.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Oscar Salvador <osalvador@suse.de>,
	Michal Hocko <mhocko@suse.com>
Subject: [PATCH v9 1/7] mm,page_alloc: Bail out earlier on -ENOMEM in alloc_contig_migrate_range
Date: Fri, 16 Apr 2021 09:00:17 +0200
Message-ID: <20210416070023.4742-2-osalvador@suse.de> (raw)
In-Reply-To: <20210416070023.4742-1-osalvador@suse.de>

Currently, __alloc_contig_migrate_range can generate -EINTR, -ENOMEM or -EBUSY,
and report them down the chain.
The problem is that when migrate_pages() reports -ENOMEM, we keep going till we
exhaust all the try-attempts (5 at the moment) instead of bailing out.

migrate_pages() bails out right away on -ENOMEM because it is considered a fatal
error. Do the same here instead of keep going and retrying.
Note that this is not fixing a real issue, just a cosmetic change. Although we
can save some cycles by backing off ealier

Signed-off-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
---
 mm/page_alloc.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 1c67c99603a3..689454692de1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8697,7 +8697,7 @@ static int __alloc_contig_migrate_range(struct compact_control *cc,
 			}
 			tries = 0;
 		} else if (++tries == 5) {
-			ret = ret < 0 ? ret : -EBUSY;
+			ret = -EBUSY;
 			break;
 		}
 
@@ -8707,6 +8707,13 @@ static int __alloc_contig_migrate_range(struct compact_control *cc,
 
 		ret = migrate_pages(&cc->migratepages, alloc_migration_target,
 				NULL, (unsigned long)&mtc, cc->mode, MR_CONTIG_RANGE);
+
+		/*
+		 * On -ENOMEM, migrate_pages() bails out right away. It is pointless
+		 * to retry again over this error, so do the same here.
+		 */
+		if (ret == -ENOMEM)
+			break;
 	}
 
 	lru_cache_enable();
-- 
2.16.3


  reply index

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-16  7:00 [PATCH v9 0/7] Make alloc_contig_range handle Hugetlb pages Oscar Salvador
2021-04-16  7:00 ` Oscar Salvador [this message]
2021-04-16  7:00 ` [PATCH v9 2/7] mm,compaction: Let isolate_migratepages_{range,block} return error codes Oscar Salvador
2021-04-16  7:00 ` [PATCH v9 3/7] mm,hugetlb: Drop clearing of flag from prep_new_huge_page Oscar Salvador
2021-04-16  7:00 ` [PATCH v9 4/7] mm,hugetlb: Split prep_new_huge_page functionality Oscar Salvador
2021-04-16  7:00 ` [PATCH v9 5/7] mm: Make alloc_contig_range handle free hugetlb pages Oscar Salvador
2021-04-16  9:49   ` Baoquan He
2021-04-16 12:14     ` Oscar Salvador
2021-04-16  7:00 ` [PATCH v9 6/7] mm: Make alloc_contig_range handle in-use " Oscar Salvador
2021-04-16  8:36   ` David Hildenbrand
2021-04-16  7:00 ` [PATCH v9 7/7] mm,page_alloc: Drop unnecessary checks from pfn_range_valid_contig Oscar Salvador

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