Joonsoo Kim [off-list ref] writes:
migrate_pages() should return number of pages not migrated or error code.
When unmap_and_move return -EAGAIN, outer loop is re-execution without
initialising nr_failed. This makes nr_failed over-counted.
So this patch correct it by initialising nr_failed in outer loop.
Signed-off-by: Joonsoo Kim <redacted>
Cc: Christoph Lameter <redacted>
Acked-by: Michal Nazarewicz <redacted>
Actually, it makes me wonder if there is any code that uses this
information. If not, it would be best in my opinion to make it return
zero or negative error code, but that would have to be checked.
quoted hunk
diff --git a/mm/migrate.c b/mm/migrate.c
index be26d5c..294d52a 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -982,6 +982,7 @@ int migrate_pages(struct list_head *from,
for(pass = 0; pass < 10 && retry; pass++) {
retry = 0;
+ nr_failed = 0;
list_for_each_entry_safe(page, page2, from, lru) {
cond_resched();
--
Best regards, _ _
.o. | Liege of Serenly Enlightened Majesty of o' \,=./ `o
..o | Computer Science, Michal "mina86" Nazarewicz (o o)
ooo +-<mina86-mina86.com>-<jid:mina86-jabber.org>--ooO--(_)--Ooo--
2012/7/17 Michal Nazarewicz [off-list ref]:
Acked-by: Michal Nazarewicz <redacted>
Thanks.
Actually, it makes me wonder if there is any code that uses this
information. If not, it would be best in my opinion to make it return
zero or negative error code, but that would have to be checked.
I think that, too.
I looked at every callsites for migrate_pages() and there is no place
which really need fail count.
This function sometimes makes caller error-prone,
so I think changing return value is preferable.
How do you think, Christoph?
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On Tue, 17 Jul 2012, JoonSoo Kim wrote:
quoted
Actually, it makes me wonder if there is any code that uses this
information. If not, it would be best in my opinion to make it return
zero or negative error code, but that would have to be checked.
I think that, too.
I looked at every callsites for migrate_pages() and there is no place
which really need fail count.
This function sometimes makes caller error-prone,
so I think changing return value is preferable.
How do you think, Christoph?
We could do that. I am not aware of anything using that information
either. However, the condition in which some pages where migrated and
others are not is not like a classic error. In many situations the moving
of the pages is done for performance reasons. This just means that the
best performant memory locations could not be used for some pages. A
situation like that may be ok for an application.
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