[PATCH] mm, migrate: count pages failing all retries in vmstat and tracepoint

[PATCH] mm, migrate: count pages failing all retries in vmstat and tracepoint

[Vlastimil Babka]

Migration tries up to 10 times to migrate pages that return -EAGAIN until it
gives up. If some pages fail all retries, they are counted towards the number
of failed pages that migrate_pages() returns. They should also be counted in
the /proc/vmstat pgmigrate_fail and in the mm_migrate_pages tracepoint.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
 mm/migrate.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index eb42671..e705324 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1152,7 +1152,8 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
 			}
 		}
 	}
-	rc = nr_failed + retry;
+	nr_failed += retry;
+	rc = nr_failed;
 out:
 	if (nr_succeeded)
 		count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded);
-- 
2.5.0

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Re: [PATCH] mm, migrate: count pages failing all retries in vmstat and tracepoint

[David Rientjes]

On Thu, 27 Aug 2015, Vlastimil Babka wrote:

> Migration tries up to 10 times to migrate pages that return -EAGAIN until it
> gives up. If some pages fail all retries, they are counted towards the number
> of failed pages that migrate_pages() returns. They should also be counted in
> the /proc/vmstat pgmigrate_fail and in the mm_migrate_pages tracepoint.
> 
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

Acked-by: David Rientjes <rientjes@google.com>

I assume nothing else other than stats and tracepoints are affected by 
this and this isn't a critical bugfix :)

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Re: [PATCH] mm, migrate: count pages failing all retries in vmstat and tracepoint

[Vlastimil Babka]

On 27.8.2015 23:02, David Rientjes wrote:
> On Thu, 27 Aug 2015, Vlastimil Babka wrote:
> 
>> Migration tries up to 10 times to migrate pages that return -EAGAIN until it
>> gives up. If some pages fail all retries, they are counted towards the number
>> of failed pages that migrate_pages() returns. They should also be counted in
>> the /proc/vmstat pgmigrate_fail and in the mm_migrate_pages tracepoint.
>>
>> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> 
> Acked-by: David Rientjes <rientjes@google.com>

Thanks.

> I assume nothing else other than stats and tracepoints are affected by 
> this and this isn't a critical bugfix :)

Yep, no stable needed :)

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