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t=1780421616; bh=o5KkLRZDKHzqzgauZa36DRNu943jxeoDnNjfgu5c58g=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=a0eGlr8cNqe5fWtVVRIkjgBEI8yknJFz5yl76rkX84Jt7Tzwx3d/Y2U8C43dPL0CS 1Y8HN2p36jLfxyiOxKF3kVZl9kM96B2bWRfwDb9y3OeetGo13hNso5NA2FVQBbadm7 VkhxzruT9bWIuKBbaV0AaFOqTnhdKh2t7Oyy6f4VC6tYFoSAP3hvUP45dm6i6KU10c ZTEt90pVa7twql29hgu3gqBLoFyoII+8UJWWPik+/hajQp+ouvJSwudD+ZcniEpZQQ mVkS8wf7NHJv8Kii8vWaKnWOZiCbeHRmo1yKOmuC6DPXOy9Fe+GmlFsZcuibmebhyG 5r624HcOZmBkA== Message-ID: <2f30e6da-0b1c-41e6-a74f-893d4ba67f65@kernel.org> Date: Tue, 2 Jun 2026 19:33:28 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/1] mm/thp: clear deferred split shrinker bits when queues drain To: Lance Yang , 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 References: <20260602043453.67597-1-lance.yang@linux.dev> <1dce1561-b42a-4322-a99f-89eba1e7c227@linux.dev> <716c7351-2641-4317-8675-e07a16a1efe2@kernel.org> <63797977-1c18-4885-8099-f5c21c80da39@linux.dev> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 359F740006 X-Rspam-User: X-Stat-Signature: 8px16j39ur3fe3ksinbaujb5j88bb58e X-HE-Tag: 1780421617-227569 X-HE-Meta: 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 Hokoo6u9 1wLMnmrKROfFwZAfYAUSeYXiCdjNXVzCJDxikUr3W9zcFZ+nhJ7p6lqJy/cx0LPBzNhICZD/A6mNgMFhVOET3O/6QiMMbA2GTAB3WRMIOoYihd5MRycOSC6hUEGdcuwj5fQfWKmCjpLV43PUXX4Xj3B2ccWf2CNj3Y8nbdAX23rE4ezqiYgAvEhCdqO5tNk3cRJJeaplTT8vR/1ZkJ+Ghy9rSGi9AJ2/HfPzu3EWlURsLsJ9DQX/wNbU/exHOFZwuy4caA2S2vUCFoECra3hQXnfMrQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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) -- Cheers, David