On Mon, Feb 21, 2011 at 10:04 PM, Johannes Weiner [off-list ref] wrote:

On Mon, Feb 21, 2011 at 12:17:17AM +0900, Minchan Kim wrote:

quoted

Now memcg in unmap_and_move checks BUG_ON of charge.
But mem_cgroup_prepare_migration returns either 0 or -ENOMEM.
If it returns -ENOMEM, it jumps out unlock without the check.
If it returns 0, it can pass BUG_ON. So it's meaningless.
Let's remove it.

Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <redacted>
Acked-by: Daisuke Nishimura <redacted>
Acked-by: KAMEZAWA Hiroyuki <redacted>
Signed-off-by: Minchan Kim <redacted>
---
 mm/migrate.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index eb083a6..2abc9c9 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c

@@ -683,7 +683,6 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,

              rc = -ENOMEM;
              goto unlock;
      }
-     BUG_ON(charge);

You remove this assertion of the mem_cgroup_prepare_migration() return
value but only add a comment about the expectations in the next patch.

Could you write a full-blown kerneldoc on mem_cgroup_prepare_migration
and remove this BUG_ON() in the same patch?

Okay. I could.




-- 
Kind regards,
Minchan Kim

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