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Thu, 24 Apr 2025 12:42:04 -0700 (PDT) Date: Thu, 24 Apr 2025 15:42:00 -0400 From: Johannes Weiner To: Wenchao Hao Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/compaction: do not break pages whose order is larger than target order Message-ID: <20250424194200.GD840@cmpxchg.org> References: <20250424153815.4003-1-haowenchao22@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250424153815.4003-1-haowenchao22@gmail.com> X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 9CC521C000F X-Stat-Signature: rzqcmdwp6nf79kkqbxzpkyk4j3buq5na X-HE-Tag: 1745523725-65298 X-HE-Meta: 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 Nz6oMSVC 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Apr 24, 2025 at 11:38:15PM +0800, Wenchao Hao wrote: > When scanning free pages for memory compaction, if the compaction target > order is explicitly specified, do not split pages in buddy whose order > are larger than compaction target order. Have you observed this to be an issue in practice? compact_finished() would have bailed if such a page had existed. compaction_capture() would steal such a page upon production. It could help with blocks freed by chance from somewhere else, where you'd preserve it to grab it later from the allocation retry. But if that's the target, it might be better to indeed isolate the page, and then capture it inside compaction_alloc()?