Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Wed, 28 Jul 2021 12:43:26 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Shakeel Butt <shakeelb@google.com>
Cc:     Michal Hocko <mhocko@suse.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Roman Gushchin <guro@fb.com>, cgroups@vger.kernel.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] memcg: cleanup racy sum avoidance code
Message-Id: <20210728124326.a3e6cc29f670062185fb57d7@linux-foundation.org>
In-Reply-To: <20210728012243.3369123-1-shakeelb@google.com>
References: <20210728012243.3369123-1-shakeelb@google.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Tue, 27 Jul 2021 18:22:43 -0700 Shakeel Butt <shakeelb@google.com> wrote:

> We used to have per-cpu memcg and lruvec stats and the readers have to
> traverse and sum the stats from each cpu. This summing was racy and may
> expose transient negative values. So, an explicit check was added to
> avoid such scenarios. Now these stats are moved to rstat infrastructure
> and are no more per-cpu, so we can remove the fixup for transient
> negative values.

We can't do anything about the same code in lruvec_page_state_local()?