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From: Shakeel Butt To: Qi Zheng Cc: hannes@cmpxchg.org, hughd@google.com, mhocko@suse.com, roman.gushchin@linux.dev, muchun.song@linux.dev, david@kernel.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, harry.yoo@oracle.com, imran.f.khan@oracle.com, kamalesh.babulal@oracle.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, chenridong@huaweicloud.com, mkoutny@suse.com, akpm@linux-foundation.org, hamzamahfooz@linux.microsoft.com, apais@linux.microsoft.com, lance.yang@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng , Chen Ridong Subject: Re: [PATCH v2 01/28] mm: memcontrol: remove dead code of checking parent memory cgroup Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: A99E34000B X-Stat-Signature: uk7c1aubuemu81g5mu5ir6dsr6ch1zjy X-HE-Tag: 1766100704-869887 X-HE-Meta: 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 BYJaGbVP OivW8K4JYVpFcpZ92yPScNDh5DpYoKF/Krj5ifXU3gDarMHyPA+XidRDcfGNaDqa9XK6EJN06v9WNIiJzAhfNkjLa4djX2ioP2JVJvfmRLbqdLF3ze2FxG5TRtt82ERW6aW59egpFUWGiEFDsAx3A6qhcfHwOjnYB/osSlZ9BbclSx+Uc7QzVjbcTC/2xIiZZYD7pUrX+LkNJUsfPdDe+C65zdL63QX5Exj1CVlX4oIjplKX1dpc7Mo9wcUJL4wOY6zOfgpeEBDtrPpRmmXg9r01L/Bw4SYYIiZysMqLxRFWtkvSrhYFefqTVNu6uqk/9D5UKy7+tRljQZ2sPrxwujT6CuA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, 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 Wed, Dec 17, 2025 at 03:27:25PM +0800, Qi Zheng wrote: > From: Muchun Song > > Since the no-hierarchy mode has been deprecated after the commit: > > commit bef8620cd8e0 ("mm: memcg: deprecate the non-hierarchical mode"). > > As a result, parent_mem_cgroup() will not return NULL except when passing > the root memcg, and the root memcg cannot be offline. Hence, it's safe to > remove the check on the returned value of parent_mem_cgroup(). Remove the > corresponding dead code. > > Signed-off-by: Muchun Song > Acked-by: Roman Gushchin > Acked-by: Johannes Weiner > Signed-off-by: Qi Zheng > Reviewed-by: Harry Yoo > Reviewed-by: Chen Ridong Acked-by: Shakeel Butt