From: Johannes Weiner <hannes@cmpxchg.org>
To: Shakeel Butt <shakeelb@google.com>
Cc: "Yosry Ahmed" <yosryahmed@google.com>,
"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>,
"Muchun Song" <muchun.song@linux.dev>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Michal Koutný" <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()
Date: Tue, 28 Mar 2023 14:47:46 -0400 [thread overview]
Message-ID: <ZCM2UseWAhahYVtS@cmpxchg.org> (raw)
In-Reply-To: <CALvZod5_NVTrYUhLjc3Me=CC6y3R4bhA71mCt-jXo0rX+2zUxw@mail.gmail.com>
On Tue, Mar 28, 2023 at 08:18:11AM -0700, Shakeel Butt 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 */
>
> I think the only reason we use rcu lock is due to
> mem_cgroup_from_id(). Maybe we should add mem_cgroup_tryget_from_id().
> The other caller of mem_cgroup_from_id() in vmscan is already doing
> the same and could use mem_cgroup_tryget_from_id().
Good catch. Nothing else in there is protected by RCU. We can just
hold the ref instead.
> Though this can be done separately to this series (if we decide to do
> it at all).
Agreed
WARNING: multiple messages have this Message-ID (diff)
From: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
To: Shakeel Butt <shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Cc: "Yosry Ahmed"
<yosryahmed-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
"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>,
"Muchun Song"
<muchun.song-fxUVXftIFDnyG1zEObXtfA@public.gmane.org>,
"Andrew Morton"
<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
"Michal Koutný" <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
Subject: Re: [PATCH v1 7/9] workingset: memcg: sleep when flushing stats in workingset_refault()
Date: Tue, 28 Mar 2023 14:47:46 -0400 [thread overview]
Message-ID: <ZCM2UseWAhahYVtS@cmpxchg.org> (raw)
In-Reply-To: <CALvZod5_NVTrYUhLjc3Me=CC6y3R4bhA71mCt-jXo0rX+2zUxw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
On Tue, Mar 28, 2023 at 08:18:11AM -0700, Shakeel Butt 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 */
>
> I think the only reason we use rcu lock is due to
> mem_cgroup_from_id(). Maybe we should add mem_cgroup_tryget_from_id().
> The other caller of mem_cgroup_from_id() in vmscan is already doing
> the same and could use mem_cgroup_tryget_from_id().
Good catch. Nothing else in there is protected by RCU. We can just
hold the ref instead.
> Though this can be done separately to this series (if we decide to do
> it at all).
Agreed
next prev parent reply other threads:[~2023-03-28 18:47 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-28 6:16 [PATCH v1 0/9] memcg: make rstat flushing irq and sleep friendly Yosry Ahmed
2023-03-28 6:16 ` Yosry Ahmed
2023-03-28 6:16 ` [PATCH v1 1/9] cgroup: rename cgroup_rstat_flush_"irqsafe" to "atomic" Yosry Ahmed
2023-03-28 6:16 ` Yosry Ahmed
2023-03-28 13:24 ` Shakeel Butt
2023-03-28 13:24 ` Shakeel Butt
2023-03-28 17:42 ` Johannes Weiner
2023-03-28 17:42 ` Johannes Weiner
2023-03-28 6:16 ` [PATCH v1 2/9] memcg: rename mem_cgroup_flush_stats_"delayed" to "ratelimited" Yosry Ahmed
2023-03-28 13:25 ` Shakeel Butt
2023-03-28 13:25 ` Shakeel Butt
2023-03-28 17:42 ` Johannes Weiner
2023-03-28 17:42 ` Johannes Weiner
2023-03-28 6:16 ` [PATCH v1 3/9] memcg: do not flush stats in irq context Yosry Ahmed
2023-03-28 13:26 ` Shakeel Butt
2023-03-28 13:26 ` Shakeel Butt
2023-03-28 17:43 ` Johannes Weiner
2023-03-28 6:16 ` [PATCH v1 4/9] cgroup: rstat: add WARN_ON_ONCE() if flushing outside task context Yosry Ahmed
2023-03-28 14:59 ` Shakeel Butt
2023-03-28 14:59 ` Shakeel Butt
2023-03-28 17:49 ` Johannes Weiner
2023-03-28 18:59 ` Yosry Ahmed
2023-03-28 18:59 ` Yosry Ahmed
2023-03-28 22:18 ` Yosry Ahmed
2023-03-28 22:18 ` Yosry Ahmed
2023-03-28 6:16 ` [PATCH v1 5/9] memcg: replace stats_flush_lock with an atomic Yosry Ahmed
2023-03-28 14:15 ` Shakeel Butt
2023-03-28 14:15 ` Shakeel Butt
2023-03-28 18:52 ` Yosry Ahmed
2023-03-28 18:52 ` Yosry Ahmed
2023-03-28 19:28 ` Shakeel Butt
2023-03-28 19:28 ` Shakeel Butt
2023-03-28 19:34 ` Yosry Ahmed
2023-03-28 19:34 ` Yosry Ahmed
2023-03-28 19:42 ` Yosry Ahmed
2023-03-28 17:53 ` Johannes Weiner
2023-03-28 17:53 ` Johannes Weiner
2023-03-28 6:16 ` [PATCH v1 6/9] memcg: sleep during flushing stats in safe contexts Yosry Ahmed
2023-03-28 15:09 ` Shakeel Butt
2023-03-28 15:09 ` Shakeel Butt
2023-03-28 18:35 ` Johannes Weiner
2023-03-28 18:45 ` Yosry Ahmed
2023-03-28 18:45 ` Yosry Ahmed
2023-03-28 19:06 ` Johannes Weiner
2023-03-28 19:06 ` Johannes Weiner
2023-03-28 19:26 ` Yosry Ahmed
2023-03-28 19:26 ` Yosry Ahmed
2023-03-28 6:16 ` [PATCH v1 7/9] workingset: memcg: sleep when flushing stats in workingset_refault() Yosry Ahmed
2023-03-28 15:18 ` Shakeel Butt
2023-03-28 15:18 ` Shakeel Butt
2023-03-28 18:47 ` Johannes Weiner [this message]
2023-03-28 18:47 ` Johannes Weiner
2023-03-28 19:25 ` Yosry Ahmed
2023-03-28 18:43 ` Johannes Weiner
2023-03-28 18:43 ` Johannes Weiner
2023-03-28 6:16 ` [PATCH v1 8/9] vmscan: memcg: sleep when flushing stats during reclaim Yosry Ahmed
2023-03-28 6:16 ` Yosry Ahmed
2023-03-28 15:19 ` Shakeel Butt
2023-03-28 15:19 ` Shakeel Butt
2023-03-28 19:01 ` Yosry Ahmed
2023-03-28 19:01 ` Yosry Ahmed
2023-03-28 19:29 ` Shakeel Butt
2023-03-28 19:29 ` Shakeel Butt
2023-03-28 18:49 ` Johannes Weiner
2023-03-28 6:16 ` [PATCH v1 9/9] memcg: do not modify rstat tree for zero updates Yosry Ahmed
2023-03-28 15:20 ` Shakeel Butt
2023-03-28 15:20 ` Shakeel Butt
2023-03-28 18:50 ` Johannes Weiner
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