Re: [PATCH 1/2] cgroup: Make operations on the cgroup root_list RCU safe

Siddh Raman Pant
2024-12-02T10:27:03Z

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On Mon, Dec 02 2024 at 15:47:00 +0530, Greg Kroah-Hartman wrote:
> On Mon, Dec 02, 2024 at 03:41:01PM +0530, Siddh Raman Pant wrote:
> > From: Yafang Shao <laoar.shao@gmail.com>
> >
> > commit d23b5c577715892c87533b13923306acc6243f93 upstream.
> >
> > At present, when we perform operations on the cgroup root_list, we must
> > hold the cgroup_mutex, which is a relatively heavyweight lock. In reality,
> > we can make operations on this list RCU-safe, eliminating the need to hold
> > the cgroup_mutex during traversal. Modifications to the list only occur in
> > the cgroup root setup and destroy paths, which should be infrequent in a
> > production environment. In contrast, traversal may occur frequently.
> > Therefore, making it RCU-safe would be beneficial.
> >
> > Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> > Signed-off-by: Tejun Heo <tj@kernel.org>
> > [fp: adapt to 5.10 mainly because of changes made by e210a89f5b07
> > ("cgroup.c: add helper __cset_cgroup_from_root to cleanup duplicated
> > codes")]
> > Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
> > [Shivani: Modified to apply on v5.4.y]
> > Signed-off-by: Shivani Agarwal <shivani.agarwal@broadcom.com>
> > Reviewed-by: Siddh Raman Pant <siddh.raman.pant@oracle.com>
>
> I'm confused. You do know what signed-off-by means, right? When
> sending a patch on, you MUST sign off on it.

Even if I'm just *forwarding* the patch already posted on the mailing
list? I just added an r-b for the patch because I reviewed it, and did
no changes.

I'm sorry if I mistook the convention. In that case, the previous
patche emails I had sent has the signoff. I had thought that was
incorrect.

Thanks,
Siddh

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