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 194DF606A334 for ; Thu, 5 Nov 2026 08:00:02 +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=rBz6MU/y; dkim=fail reason="signature verification failed" (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=guQbtF2j DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To: Content-Type:MIME-Version:References:Message-ID:Subject: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-Unsubscribe-Post:List-Owner; bh=b3t/AZZXgpUUBPoN/8EcWLM6aSitZao8sMvkUu7sQcw=; b=rBz6MU/y//gyWMsXF5/5pBTsGs tgNPMpT/Lm/B0b1IxXaWAI0p/ZajH/eIj46X7ETr0re2gIiVVgvkL3IXYQJAYomuTLhBt78oLdZtb R9MDOBtWrG5gPKjauGei5vFz3AmuKFw7FYaYAlvoMHlUsxZ9mupDkamWFdjBJDPr5wxwBVHS/eLOT DsehCXrj3Q8LXAM7Bb2l/aCsOEmcV2N8aQPxX34EhHXLXss56lVyjmzSLoI31h1k33ShVeVtdbBC2 DZyhJ+ThEucvsMTxMLrg04eAPNG49SqQ0W9jm9cGlmWFQH8KKgayN6giVIqqcchjwpfz8uRsvwEaf sRIIay+w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xOsO9-000000085Kk-2dFS; Thu, 05 Nov 2026 08:00:01 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xOsO6-000000085Jl-37PP for kexec@lists.infradead.org; Thu, 05 Nov 2026 07:59:58 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 6BB6C43B86; Thu, 5 Nov 2026 07:59:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 425191F0093A; Thu, 5 Nov 2026 07:59:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793865598; bh=b3t/AZZXgpUUBPoN/8EcWLM6aSitZao8sMvkUu7sQcw=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=guQbtF2jldVKgx4ac787ghXRGdDM4Ye6jRjYUwcllIkG+O5epTzarqTG/si+Dq7cd 8SAQXX3JwughkvqUx9Ef6WOTuPu9qLF3Qyqyf+MPL0zMS+bKGmlqJ8zmyzBmZqD3vF dEt4/oPS7+PqkIpO9cQ2jJSEsfB3Kp4ifdiqTxmcNuNuT1pIexCUI/Ft441pXEgt4s ltwwL3cFcpsnoAa45emlUhoxiDyKEHWddO+SR1XkpvsE8z9U9ysIjcLz9ege4L4IUV ZGHcgwYNvLUFYWrREJXvQ3Ph63X2uBayjKz3okeaKiP2/QLBfaDLvop+6MMV6CpbQr hdR+Mx+Mq+T3w== Date: Thu, 5 Nov 2026 09:59:50 +0200 From: Mike Rapoport To: "Jose A. Perez de Azpillaga" Subject: Re: [PATCH v2] memblock: don't allocate new reserve_mem regions on a KHO boot Message-ID: References: <20261104204235.9066-1-azpijr@gmail.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261104204235.9066-1-azpijr@gmail.com> X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Tony Luck , Pasha Tatashin , linux-mm@kvack.org, Kees Cook , Changyuan Lyu , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Alexander Graf , Andrew Morton , Pratyush Yadav Sender: "kexec" X-Spam-Status: No, score=-13.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_EF,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=ham 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 On Wed, Nov 04, 2026 at 09:42:17PM +0100, Jose A. Perez de Azpillaga wrote: > On a KHO boot, a reserve_mem region that can't be revived is allocated > from KHO_NOPRSRV memory, which includes the bootmem the next kernel > boots out of. With CONFIG_KEXEC_HANDOVER_DEBUG, preserving the region > then fails: > > WARNING: kernel/liveupdate/kexec_handover.c:1245 at kho_preserve_pages+0x168/0x180 > failed to prepare memblock FDT for KHO: -22 > > Without it, the next kernel puts its memmap on top of the region and > the ramoops records in it are lost. > > There is no use case for adding regions across a live update, so fail > instead of allocating, and drop the TODO. > > Fixes: f99230780211 ("memblock: add KHO support for reserve_mem") > Signed-off-by: Jose A. Perez de Azpillaga > --- > Changes in v2: > - fail on a KHO boot instead of allocating outside bootmem, as agreed > with Pratyush [1]. this drops v1's patch 1. > - not an RFC anymore. > - based on v7.4-rc1. > > v1: https://lore.kernel.org/all/20261021211058.83483-3-azpijr@gmail.com/ > > [1] https://lore.kernel.org/all/2vxzfqxglrg6.fsf@kernel.org/ > > mm/memblock.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/mm/memblock.c b/mm/memblock.c > index a450092a80fb..e325e0542c9a 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -2827,7 +2827,16 @@ static int __init reserve_mem(char *p) > if (reserve_mem_kho_revive(name, size, align)) > return 1; > > - /* TODO: Allocation must be outside of KHO_NOPRSRV region */ > + /* > + * On a KHO boot memblock only allocates from KHO_NOPRSRV memory here, > + * which includes the bootmem the next kernel boots out of. Only regions > + * handed over by the previous kernel are supported. > + */ > + if (is_kho_boot()) { This breaks memblock tests, please add a stub there. > + pr_err("reserve_mem: can't allocate \"%s\" on a KHO boot\n", name); > + return -EOPNOTSUPP; > + } > + > start = memblock_phys_alloc(size, align); > if (!start) { > pr_err("reserve_mem: memblock allocation failed\n"); > > base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4 > -- > 2.56.0 > -- Sincerely yours, Mike.