From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 19B16D72353 for ; Fri, 23 Jan 2026 08:53:54 +0000 (UTC) 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:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=FSbY3XgNEeMt7RDjgwXfpbnZxu/CxSRhlv5jLZ5PvPA=; b=2qeM1+pwYUm9b2HKDM1+4W2SxJ g600AjRmbEO7LeDIk+d1D8o1AdTUxRrBiduezi6ssCHN9/bs1hjNbGo/OUB5prhH6/+/Yh4BYwqGY NhMGDEVbm7ykW8PmprzapJqPxzPp5e0FbmQY4AjScQHS+NmEOucALDLeQYHzfmDKGkArHRzFoHEbg /e606UOfO66FWs1aMBteh0tQzAXuruwthRjS4IwlW4X64Ss6USR3VTSXffc9xy7BJSkcna+HdHykN PTSzNJLyIXMOzMtj3UW2MZ4/OZVmBCGr4g5pV7WwDFu3Rsjhv2IkZllDN8aewgzDUryNUgx56NKuW dx/eVJMA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vjCvP-00000008VXf-17DY; Fri, 23 Jan 2026 08:53:51 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vjCvN-00000008VXK-2zbl for kexec@lists.infradead.org; Fri, 23 Jan 2026 08:53:50 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 59399434FE; Fri, 23 Jan 2026 08:53:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F1591C4CEF1; Fri, 23 Jan 2026 08:53:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769158429; bh=8xDScLcsy5OFgIJg5rseIw23Z3H5/7lWSJmJgApIXko=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=EJyy6q4GWlNjzBtY8qzSezHb7bGJ0MPYYNHtLo9jOXlGE/DhGzq1hfsdoLsqjLcHB KyHB/f8pdvDLTlYmTUYPNPK3Abt0FTBwhzIVXmzVsQmfZp8XB1Fdam7mJLMGII6GzU vGYWSG3J6wWzp/HHPspEPHFPwJiVIyoFxLIrAQoi8SlYn+5CFFzJUw6NavLlmM8SZc we7Wuh+48gW6nIFohR3yz54yhjHR4iYs2YXbW8XS6JyGqb/xIdxXwTjAIncCpcVpp4 JnJb3EpXp66eRrCBIGWkp71VvVprmAHUEBHJVAXxdycnZQtMG+rVlM2T1F+sYDB5UL o13nTXz1H/wWw== Date: Fri, 23 Jan 2026 10:53:42 +0200 From: Mike Rapoport To: Andrew Morton Cc: Evangelos Petrongonas , Pasha Tatashin , Pratyush Yadav , Alexander Graf , Jason Miu , linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org, nh-open-source@amazon.com Subject: Re: [PATCH v2] kho: skip memoryless NUMA nodes when reserving scratch areas Message-ID: References: <20260120175913.34368-1-epetron@amazon.de> <20260122152112.1a8be8e7bdab72631234cd69@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260122152112.1a8be8e7bdab72631234cd69@linux-foundation.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260123_005349_778651_21D38B1A X-CRM114-Status: GOOD ( 12.73 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On Thu, Jan 22, 2026 at 03:21:12PM -0800, Andrew Morton wrote: > On Tue, 20 Jan 2026 17:59:11 +0000 Evangelos Petrongonas wrote: > > > kho_reserve_scratch() iterates over all online NUMA nodes to allocate > > per-node scratch memory. On systems with memoryless NUMA nodes (nodes > > that have CPUs but no memory), memblock_alloc_range_nid() fails because > > there is no memory available on that node. This causes KHO initialization > > to fail and kho_enable to be set to false. > > > > Some ARM64 systems have NUMA topologies where certain nodes contain only > > CPUs without any associated memory. These configurations are valid and > > should not prevent KHO from functioning. > > > > Fix this by only counting nodes that have memory (N_MEMORY state) and > > skip memoryless nodes in the per-node scratch allocation loop. > > > > So kho is unusable on such machines. > > Should we backport this? I'm thinking > > Fixes: 3dc92c311498 ("kexec: add Kexec HandOver (KHO) generation helpers"). It's only for v6.18, but sure, why not. -- Sincerely yours, Mike.