From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Lance Yang <lance.yang@linux.dev>,
akpm@linux-foundation.org, hannes@cmpxchg.org
Cc: ljs@kernel.org, shakeel.butt@linux.dev, mhocko@kernel.org,
david@fromorbit.com, roman.gushchin@linux.dev,
muchun.song@linux.dev, qi.zheng@linux.dev, yosry.ahmed@linux.dev,
ziy@nvidia.com, liam@infradead.org, usama.arif@linux.dev,
kas@kernel.org, vbabka@kernel.org, ryncsn@gmail.com,
zaslonko@linux.ibm.com, gor@linux.ibm.com,
wangkefeng.wang@huawei.com, baolin.wang@linux.alibaba.com,
baohua@kernel.org, dev.jain@arm.com, npache@redhat.com,
ryan.roberts@arm.com, cgroups@vger.kernel.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] mm/thp: clear deferred split shrinker bits when queues drain
Date: Tue, 2 Jun 2026 19:33:28 +0200 [thread overview]
Message-ID: <2f30e6da-0b1c-41e6-a74f-893d4ba67f65@kernel.org> (raw)
In-Reply-To: <63797977-1c18-4885-8099-f5c21c80da39@linux.dev>
On 6/2/26 14:47, Lance Yang wrote:
>
>
> On 2026/6/2 20:11, David Hildenbrand (Arm) wrote:
>> On 6/2/26 06:38, Lance Yang wrote:
>>> Sorry, I missed Johannes in Cc ...
>>>
>>
>> What's the effect of that? Would we consider it a fix that we'd want to backport?
>
> Just a stale memcg shrinker bit :) I'd treat this patch as a small
> cleanup.
>
> Once the queue is empty, count_objects() returns 0. That skips the scan,
> but shrink_slab_memcg() only clears the bit on SHRINK_EMPTY, not 0.
>
> So memcg reclaim can keep calling the shrinker even though there is
> nothing on that queue.
>
>>>
>>
>> This is against Johannes' work, right?
>
> Yep, I noticed it there, but the behavior is older.
>
>> If this is a fix, likely it would be fixing 87eaceb3faa5 ("mm: thp: make
>> deferred split shrinker memcg aware"), right?
>
> No missed reclaim, just some extra reclaim work :)
Thanks for clarifying! :)
Reviewed-by: David Hildenbrand (Arm) <david@kernel.org>
--
Cheers,
David
next prev parent reply other threads:[~2026-06-02 17:33 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-02 4:34 [PATCH 1/1] mm/thp: clear deferred split shrinker bits when queues drain Lance Yang
2026-06-02 4:38 ` Lance Yang
2026-06-02 12:11 ` David Hildenbrand (Arm)
2026-06-02 12:47 ` Lance Yang
2026-06-02 17:33 ` David Hildenbrand (Arm) [this message]
2026-06-02 10:30 ` Usama Arif
2026-06-02 20:37 ` Andrew Morton
2026-06-03 2:00 ` Lance Yang
2026-06-03 8:02 ` David Hildenbrand (Arm)
2026-06-13 2:58 ` Wei Yang
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