linux-kernel - Re: [PATCH] memcg: cleanup racy sum avoidance code

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Message-Id: <20210728124326.a3e6cc29f670062185fb57d7@linux-foundation.org>
Date:   Wed, 28 Jul 2021 12:43:26 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Shakeel Butt <shakeelb@...gle.com>
Cc:     Michal Hocko <mhocko@...e.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Roman Gushchin <guro@...com>, cgroups@...r.kernel.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] memcg: cleanup racy sum avoidance code

On Tue, 27 Jul 2021 18:22:43 -0700 Shakeel Butt <shakeelb@...gle.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()?