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 76B44E9904A for ; Fri, 10 Apr 2026 08:00:03 +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=joHTFbhY3Xpp9kkK3lQ0iapaVEXdYngH8K+Bki/pKZE=; b=xYHzl+QPxeuwXJrMpSfefYvxhH ip2+bG22jB8IK3amQf+lo/W84X7Y9BE9o8D4IqnqIvaayUVPCDo4NM+Udluj6uL/cnSpkNwbiU2KN kGcrLQKzYos/WUwor+66nGurCBpP0NAnr4BG0qYZZK4Yte4Y17k8zmplqoY3UGMtUDNr5UQp2POsC yrE/kyJVhG3QFzs56hDzwlxsGZFRlDDHF0hLN/ew3J3M2wmA7rjubLKDt9eitZN7XKuchbyCms0SA 89jCkAes9ZVr+8SWbzUDa61KEw492+PLuXyDGftgKn3VQCxviZviYdZPbee+bgBcf985XtxPmA/E5 CIhcrF1w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wB6mV-0000000Bo9m-0qwp; Fri, 10 Apr 2026 07:59:59 +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 1wB6mT-0000000Bo8C-09bN for kexec@lists.infradead.org; Fri, 10 Apr 2026 07:59:58 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id A7E2641853; Fri, 10 Apr 2026 07:59:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 93E4BC19424; Fri, 10 Apr 2026 07:59:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775807996; bh=SxrLNnYLw7RM2+RAMFd5Z9aLlerg3Bl5esgirC0unYo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=bk0e4BNXD6Yt7f4mKRojtk8ruecTagIIEG5ZStNZDXOJpUmflQARjCnJhnRz+paso roEnmnTZ/3YOwcWe24nYpk6kuNpdCBLakaiK6zYS+gzTDqq+QmsSOQ65c1vUMYn2/E tCcBDdNjvnqRhAw2ZL2IpfCQ5+NnBVg9CogjjWTrHur7cL+kyD3ZDma3KswYbArbZI zFuoEqE5eTB6wRIQI5VVRjH5zWbWsl/Yoy2UtK0na15HGAg0ukDR9WwlFRSKyB8Q5H ncK6y9yjMjyAMKOjFOa4svGHzlTF37gjH09YIdRl2GFIuzKWmdirlkLYsXuRmpqj8x lXfm1lzH96/Zg== Date: Fri, 10 Apr 2026 10:59:49 +0300 From: Mike Rapoport To: Evangelos Petrongonas Cc: Alexander Graf , Pasha Tatashin , Pratyush Yadav , Rob Herring , Saravana Kannan , Changyuan Lyu , Andrew Morton , kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, nh-open-source@amazon.com Subject: Re: [PATCH v2] kho: skip KHO for crash kernel Message-ID: References: <20260410011609.1103-1-epetron@amazon.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260410011609.1103-1-epetron@amazon.de> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260410_005957_120037_97C9C67A X-CRM114-Status: GOOD ( 25.49 ) 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 Fri, Apr 10, 2026 at 01:16:05AM +0000, Evangelos Petrongonas wrote: > kho_fill_kimage() unconditionally populates the kimage with KHO > metadata for every kexec image type. When the image is a crash kernel, > this can be problematic as the crash kernel can run in a small reserved > region and the KHO scratch areas can sit outside it. > The crash kernel then faults during kho_memory_init() when it > tries phys_to_virt() on the KHO FDT address: > > Unable to handle kernel paging request at virtual address xxxxxxxx > ... > fdt_offset_ptr+... > fdt_check_node_offset_+... > fdt_first_property_offset+... > fdt_get_property_namelen_+... > fdt_getprop+... > kho_memory_init+... > mm_core_init+... > start_kernel+... > > kho_locate_mem_hole() already skips KHO logic for KEXEC_TYPE_CRASH > images, but kho_fill_kimage() was missing the same guard. As > kho_fill_kimage() is the single point that populates image->kho.fdt > and image->kho.scratch, fixing it here is sufficient for both arm64 > and x86 as the FDT and boot_params path are bailing out when these > fields are unset. > > Fixes: d7255959b69a ("kho: allow kexec load before KHO finalization") > Signed-off-by: Evangelos Petrongonas Reviewed-by: Mike Rapoport (Microsoft) > --- > > v2: Per Mike's review [1], move the guard into kho_fill_kimage() instead > of patching the arch-level producers and consumers. This fixes > both arm64 and x86 in one place and avoids redundant checks. Tested again. > > Note regarding backporting > The offending commit was deployed with 6.19. The only other supported > kernel version with 6.18, unless I miss someting uses > ``` > if (!kho_out.finalized) > ``` > which in the case of crash kernel it shouldn't be finalised. Yes, this seems about right :) The only released kernel that has this issue is v6.19 and it will be EOL in less than a week. > [1] https://lore.kernel.org/all/ade2ExpM8ROXV-vy@kernel.org/ > > kernel/liveupdate/kexec_handover.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c > index cc68a3692905..1029fe8778f2 100644 > --- a/kernel/liveupdate/kexec_handover.c > +++ b/kernel/liveupdate/kexec_handover.c > @@ -1551,7 +1551,7 @@ int kho_fill_kimage(struct kimage *image) > int err = 0; > struct kexec_buf scratch; > > - if (!kho_enable) > + if (!kho_enable || image->type == KEXEC_TYPE_CRASH) > return 0; > > image->kho.fdt = virt_to_phys(kho_out.fdt); > -- > 2.47.3 > > > > > Amazon Web Services Development Center Germany GmbH > Tamara-Danz-Str. 13 > 10243 Berlin > Geschaeftsfuehrung: Christof Hellmis, Andreas Stieger > Eingetragen am Amtsgericht Charlottenburg unter HRB 257764 B > Sitz: Berlin > Ust-ID: DE 365 538 597 > -- Sincerely yours, Mike.