From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id AB27D606A31D for ; Sun, 15 Nov 2026 17:39:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=b3Kdmzc6 Received: by kanga.kvack.org (Postfix) id 9465E6B05B1; Sun, 15 Nov 2026 12:39:27 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 91D7D6B05B4; Sun, 15 Nov 2026 12:39:27 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 85AC76B05B5; Sun, 15 Nov 2026 12:39:27 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 60D056B05B1 for ; Sun, 15 Nov 2026 12:39:27 -0500 (EST) Received: from smtpin26.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay01.hostedemail.com (Postfix) with ESMTP id E9AF21C3BAF for ; Sun, 15 Nov 2026 17:39:26 +0000 (UTC) X-FDA: 85438065132.26.1972301 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf16.hostedemail.com (Postfix) with ESMTP id 5B22418000A for ; Sun, 15 Nov 2026 17:39:25 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=b3Kdmzc6; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf16.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1794764365; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=LuvMmI09I/yZkcgOAhuxB6XI4+QcFoSXXJuVeZFzzgs=; b=05ivYhR8WtOa+PCewxGF7Xgj5JUhJQqV+ZCvCrlZLHiyLK8f1uqoz2w+3A6o4HS1HpVOkW q7K/UXl899jngLV2BOVA9WIhIOYMT49OIp4IaDI0QTImJK6DW2BlJiyKLwrUXUOj93QFpl J8/MKHD9UnNgk+dv9n8S9dLJq05uqsE= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=b3Kdmzc6; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf16.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1794764365; b=awN372QLZGMfHuE+DqCPtP53NKX5EWvqZtuE+4nLhs27ZPfJcW01Gm7u25lawmHXYQXbxN fyCH6BpluubJX+50FakgNOZB3VpzmyDBNH5FmD4SqsnFk3tIBCyNRAo22z9iSynoe34roV fQcoT/iypZOXuPYjvyp1HfQfy+vOkno= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id DA2626117D; Sun, 15 Nov 2026 17:39:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A394A1F000C4; Sun, 15 Nov 2026 17:39:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794764364; bh=LuvMmI09I/yZkcgOAhuxB6XI4+QcFoSXXJuVeZFzzgs=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=b3Kdmzc6zR6q5nTMEJclWpKxjsTP9FwKcjQ6sFBtEe5xoLu9qJ3i50GmOc5B1CkvX c1kMrJw4q0qcpsIl0N/hXXvW+2McnXnOTPE8+W6jQxVPNrGJuONKHN93QErv5/3CJV vISHCxyh/xuGazEgvKNhjg0MST+QnVNVfdZ57rqZAly759IX/47XSXDxl3ylzs023E L8muKtVeMxSKoK5CtHTU2DkEqG6x+hf9wYETsjoxfFCWCcBB4J47qvljIHE+NNoyPq uLcmqgjdOgghfHC5P+qQ4Ye3O2579I1aexcft9YfG4EwaYJPWkQ+rpvDGV1WnYXDhn J35YsOgs06Vgg== Date: Sun, 15 Nov 2026 19:39:11 +0200 From: Mike Rapoport To: Tarun Sahu Cc: Pasha Tatashin , robin.murphy@arm.com, maz@kernel.org, will@kernel.org, David Matlack , Alexander Graf , seanjc@google.com, jgg@nvidia.com, loganodell@google.com, arnd@arndb.de, dwmw2@infradead.org, baolu.lu@linux.intel.com, Bjorn Helgaas , oupton@kernel.org, alex@shazbot.org, gle.com@google.com, pbonzini@redhat.com, Andrew Morton , kevin.tian@intel.com, joro@8bytes.org, kvmarm@lists.linux.dev, linux-pci@vger.kernel.org, Pratyush Yadav , kexec@lists.infradead.org, kvm@vger.kernel.org, iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org, skhawaja@google.com, sagis@google.com, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 02/19] kho: block: Record the entry size in the block header Message-ID: References: <20261110050202.529473-1-tarunsahu@google.com> <20261110050202.529473-3-tarunsahu@google.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261110050202.529473-3-tarunsahu@google.com> X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 5B22418000A X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS autolearn=unavailable autolearn_force=no version=4.0.1 X-Stat-Signature: hhximy4igi9ca3g795djw9u1tsw11pre X-HE-Tag: 1794764365-877186 X-HE-Meta: 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 CYRtDhmV TX07raoO2i1AZiUlLuMdBbqpXNt3VuRJs776NMdq5iqK56Qgyl94f63vI4rmJEw6J/o4P77gOcSkVJzrx7EgzHlwy3iyE1RFXi3t865RJVbVxjQZJVMbVoG9jhwbM1LlE8vyKo2AKnizgaNwsm7QsxRUw/wxLFtiMvoWlCzGrI3tUqLE4tkm6AJztSUqiZdq/r98u/N4rC74JBZEORS6r7BZ8EI08fTaxl5rdIBAJGHdpkNeOvM0QcTCTZ6cUmc6CLYAq3Q7P6Vzs9wcC5R1zwlbAn0viyMmkv4l3dS+Fn0Hz3pc= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Tue, Nov 10, 2026 at 05:01:45AM +0000, Tarun Sahu wrote: > Subsystems using the KHO Serialization Blocks framework currently do > not record the serialized entry size in the block header. The entry size > is only known to individual callers, which must track and store it in an > owning serialized data structure. If a newer source kernel adds fields > to an entry, the changed entry size breaks the stride when an older > target kernel iterates over blocks. > > Add an entry_size field to struct kho_block_header_ser. On the outgoing > side, record bs->entry_size into every block header during allocation. > During restoration, derive the entry stride directly from the block > header instead of relying on caller-supplied dimensions. The > kho_block_set_init() interface remains unchanged. A zero entry size, > or one that differs between blocks of a set, is rejected during > restoration. > > This change modifies the serialized layout of struct kho_block_header_ser Imperative voice please. > and shifts the offset of serialized entries within preserved blocks. > Bump KHO_FDT_COMPATIBLE from kho-v4 to kho-v5 so that pre-v5 and post-v5 > kernels cleanly reject mismatched handover state during boot. Also > update the stale compatible string example in the documentation. > > Suggested-by: Pratyush Yadav > Signed-off-by: Tarun Sahu > --- > include/linux/kho/abi/block.h | 10 ++++---- > include/linux/kho/abi/kexec_handover.h | 6 ++--- > kernel/liveupdate/kho_block.c | 32 +++++++++++++++++++++++--- > 3 files changed, 38 insertions(+), 10 deletions(-) > > @@ -264,8 +274,21 @@ int kho_block_set_restore(struct kho_block_set *bs, u64 head_pa) > } > > while (next_pa) { > + u64 capacity; > + > ser = phys_to_virt(next_pa); > - if (!ser->count || ser->count > bs->count_per_block) { > + if (!ser->entry_size || (entry_size && ser->entry_size != entry_size)) { > + pr_warn("Block contains invalid entry size: %llu\n", > + ser->entry_size); > + err = -EINVAL; > + goto err_destroy; > + } > + entry_size = ser->entry_size; > + bs->entry_size = entry_size; > + capacity = (KHO_BLOCK_SIZE - sizeof(*ser)) / bs->entry_size; > + bs->count_per_block = capacity; Nit: can't we just initialize bs->count_per_block directly and drop 'capacity' and the change of the following line? We are not very strict with 80-chars limit in kho/luo anyway. > + > + if (!ser->count || ser->count > capacity) { > pr_warn("Block contains invalid entry count: %llu\n", > ser->count); > err = -EINVAL; -- Sincerely yours, Mike.