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Date:   Tue, 28 Mar 2023 14:43:21 -0400
From:   Johannes Weiner <hannes@cmpxchg.org>
To:     Yosry Ahmed <yosryahmed@google.com>
Cc:     Tejun Heo <tj@kernel.org>, Josef Bacik <josef@toxicpanda.com>,
        Jens Axboe <axboe@kernel.dk>,
        Zefan Li <lizefan.x@bytedance.com>,
        Michal Hocko <mhocko@kernel.org>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Shakeel Butt <shakeelb@google.com>,
        Muchun Song <muchun.song@linux.dev>,
        Andrew Morton <akpm@linux-foundation.org>,
        Michal =?iso-8859-1?Q?Koutn=FD?= <mkoutny@suse.com>,
        Vasily Averin <vasily.averin@linux.dev>,
        cgroups@vger.kernel.org, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        bpf@vger.kernel.org
Subject: Re: [PATCH v1 7/9] workingset: memcg: sleep when flushing stats in
 workingset_refault()
Message-ID: <ZCM1Sayt3nYZ9LL9@cmpxchg.org>
References: <20230328061638.203420-1-yosryahmed@google.com>
 <20230328061638.203420-8-yosryahmed@google.com>
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On Tue, Mar 28, 2023 at 06:16:36AM +0000, Yosry Ahmed wrote:
> @@ -406,6 +406,8 @@ void workingset_refault(struct folio *folio, void *shadow)
>  	unpack_shadow(shadow, &memcgid, &pgdat, &eviction, &workingset);
>  	eviction <<= bucket_order;
>  
> +	/* Flush stats (and potentially sleep) before holding RCU read lock */
> +	mem_cgroup_flush_stats_ratelimited();
>  	rcu_read_lock();

Minor nit, but please keep the lock section visually separated by an
empty line between the flush and the rcu lock.

Other than that,

Acked-by: Johannes Weiner <hannes@cmpxchg.org>