From mboxrd@z Thu Jan  1 00:00:00 1970
From: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
Subject: Re: [PATCH v1 7/9] workingset: memcg: sleep when flushing stats in
 workingset_refault()
Date: Tue, 28 Mar 2023 14:43:21 -0400
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To: Yosry Ahmed <yosryahmed-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Cc: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Josef Bacik <josef-DigfWCa+lFGyeJad7bwFQA@public.gmane.org>, Jens Axboe <axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org>, Zefan Li <lizefan.x-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org>, Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Roman Gushchin <roman.gushchin-fxUVXftIFDnyG1zEObXtfA@public.gmane.org>, Shakeel Butt <shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Muchun Song <muchun.song-fxUVXftIFDnyG1zEObXtfA@public.gmane.org>, Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, Michal =?iso-8859-1?Q?Koutn=FD?= <mkoutny-IBi9RG/b67k@public.gmane.org>, Vasily Averin <vasily.averin-fxUVXftIFDnyG1zEObXtfA@public.gmane.org>, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, bpf-u79uwXL29TY76Z2rM5mHXA@public.gmane.org

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-druUgvl0LCNAfugRpC6u6w@public.gmane.org>