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smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 08AB5606A31C for ; Tue, 20 Oct 2026 14:52:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 776E71F000C4; Tue, 20 Oct 2026 14:52:26 +0000 (UTC) Message-ID: <11264869-00ad-44ea-b39c-a78347af0ee1@kernel.org> Date: Tue, 20 Oct 2026 16:52:19 +0200 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v2 0/4] mm: compaction: mTHP-friendly memory compaction Content-Language: en-US To: Bo Zhang , akpm@linux-foundation.org, david@kernel.org Cc: surenb@google.com, mhocko@suse.com, brendan.jackman@linux.dev, hannes@cmpxchg.org, ziy@nvidia.com, ljs@kernel.org, liam@infradead.org, rppt@kernel.org, qi.zheng@linux.dev, shakeel.butt@linux.dev, kasong@tencent.com, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, zhaonanzhe@xiaomi.com, lipengfei28@xiaomi.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Bo Zhang References: <20261001001412.3837085-1-zhangbo56@xiaomi.com> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/1/26 02:14, Bo Zhang wrote: > Open questions: > > 1. In skip_isolation_on_order() and elsewhere, the target order is read > from huge_anon_orders_always directly, since during proactive > compaction cc->order is -1 (via compact_memory) and there is no clean > way to plumb the mTHP order down. Isn't using struct compact_control clean enough? There's already many fields like bool direct_compaction; /* False from kcompactd or /proc/... */ bool proactive_compaction; /* kcompactd proactive compaction */ Who says is_via_compact_memory() cannot be refactored into something using these kinds of fields and not 'order' being -1, which could be then used as the target order. > This variable can change under > userspace at any time, making the semantics fragile. Ideas on how to > pass the target order through the proactive path cleanly are welcome. >