From: Waiman Long <longman@redhat.com>
To: Roman Gushchin <guro@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
linux-mm@kvack.org, Shakeel Butt <shakeelb@google.com>,
Muchun Song <songmuchun@bytedance.com>
Subject: Re: [PATCH 1/3] mm, memcg: Don't put offlined memcg into local stock
Date: Mon, 31 Jan 2022 12:09:09 -0500 [thread overview]
Message-ID: <95ba1931-e9c9-45c3-b080-d28f2ad368a7@redhat.com> (raw)
In-Reply-To: <YfgV2iiaVlR0hozD@carbon.dhcp.thefacebook.com>
On 1/31/22 12:01, Roman Gushchin wrote:
> On Sun, Jan 30, 2022 at 10:55:56PM -0500, Waiman Long wrote:
>> On 10/1/21 19:51, Roman Gushchin wrote:
>>> On Fri, Oct 01, 2021 at 03:09:36PM -0400, Waiman Long wrote:
>>>> When freeing a page associated with an offlined memcg, refill_stock()
>>>> will put it into local stock delaying its demise until another memcg
>>>> comes in to take its place in the stock. To avoid that, we now check
>>>> for offlined memcg and go directly in this case to the slowpath for
>>>> the uncharge via the repurposed cancel_charge() function.
>>> Hi Waiman!
>>>
>>> I'm afraid it can make a cleanup of a dying cgroup slower: for every
>>> released page we'll potentially traverse the whole cgroup tree and
>>> decrease atomic page counters.
>>>
>>> I'm not sure I understand the benefits we get from this change which
>>> do justify the slowdown on the cleanup path.
>>>
>>> Thanks!
>> I was notified of a lockdep splat that this patch may help to prevent.
> Would you mind to test this patch:
> https://www.spinics.net/lists/cgroups/msg31244.html ?
>
> It should address this dependency.
Thanks for the pointer. I believe that your patch should be able to
address this circular locking dependency.
Feel free to add my
Reviewed-by: Waiman Long <longman@redhat.com>
Cheers,
Longman
next prev parent reply other threads:[~2022-01-31 17:09 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-01 19:09 [PATCH 0/3] mm, memcg: Miscellaneous cleanups Waiman Long
2021-10-01 19:09 ` [PATCH 1/3] mm, memcg: Don't put offlined memcg into local stock Waiman Long
2021-10-01 21:17 ` kernel test robot
2021-10-01 23:06 ` kernel test robot
2021-10-01 23:51 ` Roman Gushchin
2021-10-02 1:54 ` Waiman Long
2022-01-31 3:55 ` Waiman Long
2022-01-31 17:01 ` Roman Gushchin
2022-01-31 17:09 ` Waiman Long [this message]
2022-01-31 17:15 ` Waiman Long
2022-01-31 17:19 ` Roman Gushchin
2022-01-31 17:25 ` Waiman Long
2022-01-31 18:00 ` Shakeel Butt
2022-01-31 17:15 ` Roman Gushchin
2021-10-01 19:09 ` [PATCH 2/3] mm, memcg: Remove obsolete memcg_free_kmem() Waiman Long
2021-10-02 0:01 ` Roman Gushchin
2021-10-02 2:03 ` Waiman Long
2021-10-01 19:09 ` [PATCH 3/3] mm, memcg: Ensure valid memcg from objcg within a RCU critical section Waiman Long
2021-10-01 20:24 ` Shakeel Butt
2021-10-01 20:34 ` Waiman Long
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