From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2968A606A33A for ; Wed, 4 Nov 2026 12:35:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=dElQIs3h; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=iTuJgPLh DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:MIME-Version: Message-ID:Date:References:In-Reply-To:Subject:Cc:To:From:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Unsubscribe-Post:List-Owner; bh=PFO6n7YvwMi4NU0WsSwg3JV5MxCZrjERTzdE+It3Nco=; b=dElQIs3hA94EBJaHMcutTKQec1 X7BV7AQsw6W3cl/1bRcTZ4+DYGjnPeY6V033gZ7+2bS2noCs7UQ2qTvR656As56L8Ih/mWaZcMj6g Y3ZvBAvg5DiYmA8kbisAFGRvoyBBIyHDxu62Pqq5Sqpp+zmpSJwY7rPN+ACyFUiYd+INEgs8pJ98E d7DVOIZUntDc742LuY58h7krja3wrL0w/w2aluYqzIeNHATJ0KTTS1HEZc3Ny9oNTDmTjFad13mCh rNbW7BmliestDYIHZ9FWcCZv75obCl+aLksQ17gUqUb/TkKlIISPMaECQL51GeNHlXps6xu8Jesj9 65o82dXg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xOaDN-00000005LOD-2VkS; Wed, 04 Nov 2026 12:35:41 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xOaDL-00000005LNw-1f2P for kexec@lists.infradead.org; Wed, 04 Nov 2026 12:35:39 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id BF3FD60F3C; Wed, 4 Nov 2026 12:35:38 +0000 (UTC) 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-Archived-By: MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" X-Spam-Status: No, score=-7.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 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