(2012/11/01 4:44), Tejun Heo wrote:
> CGRP_WAIT_ON_RMDIR is another kludge which was added to make cgroup
> destruction rollback somewhat working. cgroup_rmdir() used to drain
> CSS references and CGRP_WAIT_ON_RMDIR and the associated waitqueue and
> helpers were used to allow the task performing rmdir to wait for the
> next relevant event.
>
> Unfortunately, the wait is visible to controllers too and the
> mechanism got exposed to memcg by 887032670d ("cgroup avoid permanent
> sleep at rmdir").
>
> Now that the draining and retries are gone, CGRP_WAIT_ON_RMDIR is
> unnecessary. Remove it and all the mechanisms supporting it. Note
> that memcontrol.c changes are essentially revert of 887032670d
> ("cgroup avoid permanent sleep at rmdir").
>
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> Reviewed-by: Michal Hocko <mhocko@xxxxxxx>
> Cc: Balbir Singh <bsingharora@xxxxxxxxx>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
plz forget my comments on v1...But...
If swap-in makes a charge before css is deactivated, pre_destroy()->force_empty()
will cause infinite loop until it finds a newly charged page in LRU. I think
force_empty() will find it by lru_drain() and can make res_coutnter to be 0.
I think we need some test with swap-in handling..Anyway,
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
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