From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C2ACC3D34A1 for ; Fri, 5 Jun 2026 18:35:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780684531; cv=none; b=SvSH9t3MCKeVhF6YJj2DEn8Xk7Pfl6QUF1ZEwWn6sS1EfwGLNtZo3u79Ccp9OKsWkgV9glowJsmCI3XBPENeKdFhF7WqdGuRfQ9xcyYaqUi0p6zjqpEZQHVhugoffO5XoQjX8V5OGsD03thC9Zb2vQuBq0I4ukg4ZuE7vCJr/GM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780684531; c=relaxed/simple; bh=ZmHYrRn2dd+FHcK0oWeoUFnAb2C1iqcvi8A5/qBbgsM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=UP1KW5Hrj27L0UCKSx0Z5JlTdlUFcR7xmapWrT2E66HLQymvuE9j6VLCRB2WcNF2jQTpOsSnc0RDvqh7DEo7LmfDSWkDrmSJcjHevqa4GyM8FIIcfiZBvX4s9TTxWq638tvK+ESqLCtL4StXGxXnL2YmoO7mEceLjyXPoL9k/uY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CgCduHIB; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="CgCduHIB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8D7C21F00899; Fri, 5 Jun 2026 18:35:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780684529; bh=//G582QmL83eTkSHOXL243u6P2jYvjAZreKxz5CziEA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=CgCduHIBqIPIikUteN8s7UcrkafZ328qitJTMRx9Gja3CtmQtqozZSz1Zo1cI3Q4a 0mf/tCWCSTcijpLqHNl9TEhAutmrsCk9GRJ+SYcGitEs482y4PCrL1BVdLCOEG9Nw4 5czURS+nx7/D/QTH4gdNW3LVBzzZLdXwdHsDgxSUn2+44JmtFlaUo9q6aiDvBG+Lgb qPA/1r89XudaEhwvOQFP0XGpFLG7C2ZCEeP6SmQ0AYVC9gh3MrgQoPi/Kr2z+gUrHP JdsoPk7nqhko/8Pvm3dp/u6IoE848ykhluss6wPDk/Al0xWHheka8i27MJ4VZZAOi3 LRjysH+vsMxAA== From: Pratyush Yadav To: Mike Rapoport , Pasha Tatashin , Pratyush Yadav , Alexander Graf , Muchun Song , Oscar Salvador , David Hildenbrand , Andrew Morton , Jason Miu , Jork Loeser Cc: kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 07/18] kho: add callback for table pages Date: Fri, 5 Jun 2026 20:34:40 +0200 Message-ID: <20260605183501.3884950-8-pratyush@kernel.org> X-Mailer: git-send-email 2.54.0.1032.g2f8565e1d1-goog In-Reply-To: <20260605183501.3884950-1-pratyush@kernel.org> References: <20260605183501.3884950-1-pratyush@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: "Pratyush Yadav (Google)" The KHO memory preservation radix tree does not mark the table pages themselves as preserved. This is done to avoid a circular dependency where preserving a page can lead of allocating other preserved pages. This means any walker looking for free ranges of memory outside of scratch areas will ignore the table Add a table callback that is invoked for each table page. The callback is given the physical address of the table page. This is useful for the upcoming mechanism that discovers blocks of memory with no preserved pages and lets them be used for boot memory. Another use case is for users of the radix tree other than KHO itself. The radix tree does not preserve its own pages due to the circular dependency described above. But external users of the radix tree would need to preserve and restore their pages for the radix tree to survive past early boot. They can use this callback to do so. Signed-off-by: Pratyush Yadav (Google) --- include/linux/kho_radix_tree.h | 3 +++ kernel/liveupdate/kexec_handover.c | 12 ++++++++++++ 2 files changed, 15 insertions(+) diff --git a/include/linux/kho_radix_tree.h b/include/linux/kho_radix_tree.h index 426a9cc9bcde..ac7ba7e567e1 100644 --- a/include/linux/kho_radix_tree.h +++ b/include/linux/kho_radix_tree.h @@ -37,12 +37,15 @@ struct kho_radix_tree { /** * struct kho_radix_walk_cb - Callbacks for KHO radix tree walk. * @leaf: Called on each present key in the radix tree. + * @node: Called on each node of the radix tree itself. Receives the + * physical address of the page containing the node. * * For each callback, a return value of 0 continues the walk and a non-zero * return value is directly returned to the caller. */ struct kho_radix_walk_cb { int (*leaf)(unsigned long key); + int (*node)(phys_addr_t phys); }; #ifdef CONFIG_KEXEC_HANDOVER diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c index dbe075348ce4..94f18fe42c4b 100644 --- a/kernel/liveupdate/kexec_handover.c +++ b/kernel/liveupdate/kexec_handover.c @@ -285,6 +285,12 @@ static int kho_radix_walk_leaf(struct kho_radix_leaf *leaf, unsigned long key, unsigned int i; int err; + if (cb->node) { + err = cb->node(virt_to_phys(leaf)); + if (err) + return err; + } + if (!cb->leaf) return 0; @@ -307,6 +313,12 @@ static int __kho_radix_walk_tree(struct kho_radix_node *root, unsigned int shift; int err; + if (cb->node) { + err = cb->node(virt_to_phys(root)); + if (err) + return err; + } + for (i = 0; i < PAGE_SIZE / sizeof(phys_addr_t); i++) { if (!root->table[i]) continue; -- 2.54.0.1032.g2f8565e1d1-goog