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Mon, 04 Dec 2023 17:39:15 -0800 (PST) MIME-Version: 1.0 References: <20231130194023.4102148-1-nphamcs@gmail.com> <20231130194023.4102148-3-nphamcs@gmail.com> In-Reply-To: From: Nhat Pham Date: Mon, 4 Dec 2023 17:39:04 -0800 Message-ID: Subject: Re: [PATCH v8 2/6] memcontrol: implement mem_cgroup_tryget_online() To: Chris Li Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, cerasuolodomenico@gmail.com, yosryahmed@google.com, sjenning@redhat.com, ddstreet@ieee.org, vitaly.wool@konsulko.com, mhocko@kernel.org, roman.gushchin@linux.dev, shakeelb@google.com, muchun.song@linux.dev, linux-mm@kvack.org, kernel-team@meta.com, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, shuah@kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Stat-Signature: 3qjgumqo6jqi614maqzg7r6oogwb4rjs X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 8A856100005 X-HE-Tag: 1701740356-967653 X-HE-Meta: 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 ispKHT/u 82lQwqd8XDSuxT/LZcPJ2/PTv3qB8yJGSOz5fSfCDaP3Rrzvt6XUVKushPqf6mItG7vnHOidS/c+6ept0UL/js/QlDmlKzx7wzBnImlG1tIlKhvcx3wakgKL0YJO9c5pGSvD8Hk/x/6uwxuGDgpiFUZ5+ACpB9GTYqOvRAY28lq8ziTbdkvQH6l/CEvvnZkf1ZKY9Cys6KRV03VrMykOViIvFxsQzjuWmfkZY/P2G+ypsYLntMOrhAfq4UqU0WN2WVj9/7TOgeSRDQ16FA6tnpuhTykn11pP0inR+HzzU3y4Ky/znqt7si4ENCcIPBoow6ivxnEKPoCFynI1xge02voWZx6AZ3W4AWn0mKyO2y4Y+GVq2BCUMV94LsSWu3clBrsCL6uBiYAcJ1umjaaUht2oT57sdnzEUHjKa17IIDE+CNghIDdZ676Pvfv3a/ivBAW7sOWyIH3oB7gNYth/5k7CiehhRq5izY0t2jXq8sZ/YM2E= X-Bogosity: Ham, tests=bogofilter, spamicity=0.007872, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Dec 4, 2023 at 4:36=E2=80=AFPM Chris Li wrote: > > Hi Nhat, > > Very minor nitpick. This patch can fold with the later patch that uses > it. That makes the review easier, no need to cross reference different > patches. It will also make it harder to introduce API that nobody > uses. > > Chris > > On Thu, Nov 30, 2023 at 11:40=E2=80=AFAM Nhat Pham wr= ote: > > > > This patch implements a helper function that try to get a reference to > > an memcg's css, as well as checking if it is online. This new function > > is almost exactly the same as the existing mem_cgroup_tryget(), except > > for the onlineness check. In the !CONFIG_MEMCG case, it always returns > > true, analogous to mem_cgroup_tryget(). This is useful for e.g to the > > new zswap writeback scheme, where we need to select the next online > > memcg as a candidate for the global limit reclaim. > > Very minor nitpick. This patch can fold with the later patch that uses > it. That makes the review easier, no need to cross reference different > patches. It will also make it harder to introduce API that nobody > uses. I don't have a strong preference one way or the other :) Probably not worth the churn tho. > > Chris > > > > > Signed-off-by: Nhat Pham > > --- > > include/linux/memcontrol.h | 10 ++++++++++ > > 1 file changed, 10 insertions(+) > > > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > > index 7bdcf3020d7a..2bd7d14ace78 100644 > > --- a/include/linux/memcontrol.h > > +++ b/include/linux/memcontrol.h > > @@ -821,6 +821,11 @@ static inline bool mem_cgroup_tryget(struct mem_cg= roup *memcg) > > return !memcg || css_tryget(&memcg->css); > > } > > > > +static inline bool mem_cgroup_tryget_online(struct mem_cgroup *memcg) > > +{ > > + return !memcg || css_tryget_online(&memcg->css); > > +} > > + > > static inline void mem_cgroup_put(struct mem_cgroup *memcg) > > { > > if (memcg) > > @@ -1349,6 +1354,11 @@ static inline bool mem_cgroup_tryget(struct mem_= cgroup *memcg) > > return true; > > } > > > > +static inline bool mem_cgroup_tryget_online(struct mem_cgroup *memcg) > > +{ > > + return true; > > +} > > + > > static inline void mem_cgroup_put(struct mem_cgroup *memcg) > > { > > } > > -- > > 2.34.1 > >