From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793795738; b=lLQwiN/Fad7H2UYYuoayqfLuUNd9/yjOvLJkkvDZTIdigyM3LLl57SOoldTOojMBBK1T 6ckjnsEy3yFNFEqrMR9Ppag7r/kCe1W2E7wD6s/hbnHB/Y3MQMJQU9K1ZVTFqTb/t6Wbr 98lK0X9rSSpYP3/nethu0h7h7MmFwHYdm0FsJsqzkmgxZjHE/+nKbSULEOXAjOOzDv3YW cYw7KwtzOk6edtXwNtgpb+jFOAW+NQ+ERWc9KrmZPPN6lPyxcYpX6zB1poDfxPaMs7FjP Avok8wVu39oLYRu+7fX886vxn/kOBpV/u/YeqZvyagkPcK0JVAQR7Jd0MvT208TtMkQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793795738; h=Received:DKIM-Signature:From:To:Cc:Subject:In-Reply-To:References: Date:Message-ID:User-Agent:MIME-Version:Content-Type; bh=PFO6n7YvwMi4NU0WsSwg3JV5MxCZrjERTzdE+It3Nco=; b=tnX4xQPXaGalQ1k8BD/7eh4ApCuMIpCuQHjMhRzuDf9SvWkP/ls6tgEDUlosHONudrwM PsPSA+hzr2Bafnx2UkCQc26SBQLgwBJeXsq1kon6oePPZkFF/Aj24RPNYfzqnOiay1xfM vZPK0q7J1MF6GsLi95zSoOrNxo+F0X0SY9FqikBPrTAwsn1UZzFxf5NVk28h4qDhx5BN4 k/eokOUfxvgl5ubHj23leQFqNSuTpVVJ3alG2LPSlf87NfBrSHO0U/tpjpk4DDTF69dg/ PTR1gSy0pFhxv98bOafW6noYVRWE11L/kEAOn/XDvaeccWG3n+P2tvRL/XAtESA8N6g== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=iTuJgPLh; 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 A1E10606A31B for ; Wed, 4 Nov 2026 12:35:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=iTuJgPLh Received: by smtp.kernel.org (Postfix) with ESMTPSA id 204001F00919; Wed, 4 Nov 2026 12:35:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793795738; bh=PFO6n7YvwMi4NU0WsSwg3JV5MxCZrjERTzdE+It3Nco=; h=From:To:Cc:Subject:In-Reply-To:References:Date; b=iTuJgPLh5PToKdG49zOOVGH+CQ5Jys5z+yon0oacjCMpG3mh7Huv/U7eeplq8Y/4T GDeSwjJNvN2jmjilE8nwtasTYSExBga0xXx/eUBVa64gQ9G+BQyFV+JQtMkZ45fKWn vetmLgnio3ES0nDRWx1FQGPvJ2KDpxE62qLURkN+atkAyL+E1OCENc7QWMVsobG3Hg IFvB1WyFF8tMfYZKgkfKSFe4/fR5XDUYh/NuVMDndBIdcyOv4fPkC450V+FDNyPGV1 wJvr4tyZ2wG2NiH8747tItOCsS1x6aqhw5LvR9qgZPbDqZS0w4w9pylKndJjVeyBl5 Jxl/jzq3Cgkuw== From: Pratyush Yadav To: Chen Pei Cc: pratyush@kernel.org, graf@amazon.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, pasha.tatashin@soleen.com, rppt@kernel.org Subject: Re: [PATCH] kho: Skip zero-sized bootmem areas In-Reply-To: <20261027074028.13042-1-cp0613@linux.alibaba.com> (Chen Pei's message of "Tue, 27 Oct 2026 15:40:25 +0800") References: <20261026131851.9942-1-cp0613@linux.alibaba.com> <2vxzld7kpmmi.fsf@kernel.org> <20261027074028.13042-1-cp0613@linux.alibaba.com> Date: Wed, 04 Nov 2026 13:35:35 +0100 Message-ID: <2vxz8q38lqp4.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) 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 Content-Type: text/plain Hi Chen, On Tue, Oct 27 2026, Chen Pei wrote: >> Do you see zero sized lowmem or global scratch in practice? If yes, >> how? What's your setup? > > Yes. Enabling KHO for riscv64 gave me three cases. They differ in which > size ends up 0 and in what it costs, and all three are measured: [...] > >> Note that I already fixed this for per-node areas since those do end >> up with no allocations with movable_node set [0]. > > That one covers the per-node loop only; lowmem and global are still > unconditional in linux-next today, which is what cases 1, 2 and 3 above > are about. Is there anything I have not considered here? Please point > it out and I will follow up accordingly. Mike sent out [0] recently which should fix this problem. Please take a look at that, and see if it works for you. [0] https://lore.kernel.org/kexec/20261103-kho-bootmem-sizing-v1-1-45aa74098f34@kernel.org/ -- Regards, Pratyush Yadav