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Wed, 06 Jan 2021 08:19:34 -0800 (PST) Received: from localhost ([2620:10d:c093:400::5:5586]) by smtp.gmail.com with ESMTPSA id t16sm3971660wmi.3.2021.01.06.08.19.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Jan 2021 08:19:34 -0800 (PST) Date: Wed, 6 Jan 2021 16:19:33 +0000 From: Chris Down To: Hugh Dickins Cc: Andrew Morton , Hui Su , Alex Shi , Lorenzo Stoakes , Michal Hocko , Johannes Weiner , Shakeel Butt , Roman Gushchin , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] mm/memcontrol: fix warning in mem_cgroup_page_lruvec() Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: User-Agent: Mutt/2.0.3 (a51f058f) (2020-12-04) 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: Hugh Dickins writes: >Boot a CONFIG_MEMCG=y kernel with "cgroup_disabled=memory" and you are >met by a series of warnings from the VM_WARN_ON_ONCE_PAGE(!memcg, page) >recently added to the inline mem_cgroup_page_lruvec(). > >An earlier attempt to place that warning, in mem_cgroup_lruvec(), had >been careful to do so after weeding out the mem_cgroup_disabled() case; >but was itself invalid because of the mem_cgroup_lruvec(NULL, pgdat) in >clear_pgdat_congested() and age_active_anon(). > >Warning in mem_cgroup_page_lruvec() was once useful in detecting a KSM >charge bug, so may be worth keeping: but skip if mem_cgroup_disabled(). > >Fixes: 9a1ac2288cf1 ("mm/memcontrol:rewrite mem_cgroup_page_lruvec()") >Signed-off-by: Hugh Dickins Thanks. Acked-by: Chris Down