2021-12-11 16:19:00

by Wei Yang

Subject: [PATCH] cgroup: return early if it is already on preloaded list

If it is already on preloaded list, this means we have already setup
this cset properly for migration.

Let's skip this cset on this condition.

Signed-off-by: Wei Yang <[email protected]>
---
kernel/cgroup/cgroup.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 452a723d4a36..2cf729afe834 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -2648,11 +2648,11 @@ void cgroup_migrate_add_src(struct css_set *src_cset,
if (src_cset->dead)
return;

- src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root);
-
if (!list_empty(&src_cset->mg_preload_node))
return;

+ src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root);
+
WARN_ON(src_cset->mg_src_cgrp);
WARN_ON(src_cset->mg_dst_cgrp);
WARN_ON(!list_empty(&src_cset->mg_tasks));
--
2.33.1

2021-12-13 19:27:17

by Tejun Heo

Subject: Re: [PATCH] cgroup: return early if it is already on preloaded list

On Sat, Dec 11, 2021 at 04:17:29PM +0000, Wei Yang wrote:
> If it is already on preloaded list, this means we have already setup
> this cset properly for migration.
>
> Let's skip this cset on this condition.

The patch looks fine but I think description can be improved. Can you just
say that it's just relocating the root cgrp lookup which isn't used anyway
when the cset is already on the preloaded list?

Thanks.

--
tejun

2021-12-14 00:36:10

by Wei Yang

Subject: Re: [PATCH] cgroup: return early if it is already on preloaded list

On Mon, Dec 13, 2021 at 09:27:12AM -1000, Tejun Heo wrote:
>On Sat, Dec 11, 2021 at 04:17:29PM +0000, Wei Yang wrote:
>> If it is already on preloaded list, this means we have already setup
>> this cset properly for migration.
>>
>> Let's skip this cset on this condition.
>
>The patch looks fine but I think description can be improved. Can you just
>say that it's just relocating the root cgrp lookup which isn't used anyway
>when the cset is already on the preloaded list?
>

Sure, let me try to rephrase it :-)

>Thanks.
>
>--
>tejun

--
Wei Yang
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