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Fri, 19 Mar 2021 07:00:36 -0700 (PDT) MIME-Version: 1.0 References: <20210319054944.50048-1-hannes@cmpxchg.org> In-Reply-To: <20210319054944.50048-1-hannes@cmpxchg.org> From: Shakeel Butt Date: Fri, 19 Mar 2021 07:00:24 -0700 Message-ID: Subject: Re: [PATCH 1/2] mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled To: Johannes Weiner Cc: Andrew Morton , Hugh Dickins , Michal Hocko , Linux MM , Cgroups , LKML , Kernel Team Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: B70CC350B X-Stat-Signature: yg66yjsbarhf3sfp7jdgrb8zfr591fkc Received-SPF: none (google.com>: No applicable sender policy available) receiver=imf20; identity=mailfrom; envelope-from=""; helo=mail-wr1-f52.google.com; client-ip=209.85.221.52 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1616162829-426509 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: On Thu, Mar 18, 2021 at 10:49 PM Johannes Weiner wrote: > > Since commit 2d1c498072de ("mm: memcontrol: make swap tracking an > integral part of memory control"), the cgroup swap arrays are used to > track memory ownership at the time of swap readahead and swapoff, even > if swap space *accounting* has been turned off by the user via > swapaccount=0 (which sets cgroup_memory_noswap). > > However, the patch was overzealous: by simply dropping the > cgroup_memory_noswap conditionals in the swapon, swapoff and uncharge > path, it caused the cgroup arrays being allocated even when the memory > controller as a whole is disabled. This is a waste of that memory. > > Restore mem_cgroup_disabled() checks, implied previously by > cgroup_memory_noswap, in the swapon, swapoff, and swap_entry_free > callbacks. > > Fixes: 2d1c498072de ("mm: memcontrol: make swap tracking an integral part of memory control") > Reported-by: Hugh Dickins > Signed-off-by: Johannes Weiner Reviewed-by: Shakeel Butt