diff mbox series

[v7,1/7] mm,page_alloc: Bail out earlier on -ENOMEM in alloc_contig_migrate_range

Message ID 20210413104747.12177-2-osalvador@suse.de (mailing list archive)
State New, archived
Headers show
Series Make alloc_contig_range handle Hugetlb pages | expand

Commit Message

Oscar Salvador April 13, 2021, 10:47 a.m. UTC 
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>
---
 mm/page_alloc.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

Comments

Mike Kravetz April 13, 2021, 5 p.m. UTC | #1 
On 4/13/21 3:47 AM, Oscar Salvador wrote:
> 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>
diff mbox series

Patch

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();