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 AB6BAC531D0 for ; Sat, 25 Jul 2026 17:22:08 +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:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=UssDO5z6c/24JhZEgWp/dn4Lbv4f8nQsIcbdHht52iY=; b=i8eVolgHPSOYez60F6MJ5kMlKP NU1RJeF/hfhWdt2HHmslosM4SAiPRzPgkX7GcWykhVfO3U5jyFc3oflOFTvpK9bWGHUmZVvGWkJ6K hECGyrmsLlXFc6ct1znFi0L/1br1zVz62PtJ/hdPfDV8IU3ZHVMkyHNDihxmeS/3LYPCDz5o3w9tC KKTmfilnjLC0oV+/j7c3TM7DKHR0svkHGGmXtGsFhfjYRqNUNBgLceuhQOGR9xShcXkHVrjBmW0zE 6TpFqmrI03BNV4tOKzDewnhfvB4kSwQXtUMD8rBLoIF6+n0jQjLasqgkJTIXe53/pCHv/2oqeT4Wc sTjbQCRg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wng4d-00000000aQp-2Rk8; Sat, 25 Jul 2026 17:22:07 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wng4c-00000000aPY-2mKQ for kexec@lists.infradead.org; Sat, 25 Jul 2026 17:22:06 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 56A8141A04; Sat, 25 Jul 2026 17:22:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1297E1F00A3A; Sat, 25 Jul 2026 17:22:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785000126; bh=UssDO5z6c/24JhZEgWp/dn4Lbv4f8nQsIcbdHht52iY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=RBEqvIEgTiYXyg5AgNyzHgc714+8FoIDfX9G+OAjYcECsuV/zCZMqLu5C+WWrdoB4 NXUjJl5Lk1GDhYIZA7oEa+xqPtHU2IPAY1Z8KMzBJZ+zuSxOWnXHFBYeXJZA306nHA tyMeBgfwwQgGeRpLrcdv5NH/za3tzUiaQBkq+LB43zRbRzzGaiZ9ga54VYwCcixmVR K+vxC5lbDQRizyq0dkWL3mpgKJbX3WMYkgJFi7esn+f7rajc6EyM11eZaDx7JSdDoa HpBPxhCH2EXblVtNtbpT6Um2gS4ioj0Tv70cRW6++KrA4b/8/ajHTGbDMh2LGjLow2 CwaXrDsrpJLZg== 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 v4 08/21] kho: add callback for table pages Date: Sat, 25 Jul 2026 19:21:08 +0200 Message-ID: <20260725172133.4018491-9-pratyush@kernel.org> X-Mailer: git-send-email 2.55.0.229.g6434b31f56-goog In-Reply-To: <20260725172133.4018491-1-pratyush@kernel.org> References: <20260725172133.4018491-1-pratyush@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 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 9fb07c0ef18e..2044f35cf1de 100644 --- a/kernel/liveupdate/kexec_handover.c +++ b/kernel/liveupdate/kexec_handover.c @@ -288,6 +288,12 @@ 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; @@ -310,6 +316,12 @@ 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; -- 2.55.0.229.g6434b31f56-goog