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 E5915CAC59A for ; Sun, 21 Sep 2025 22:26:17 +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=0Goc4fu4E5QtA9qLOcM+4h+EpWxYEBSIjsqPof2KABk=; b=chaFqhuvYu0JVpOfYCIoo77Pne bAe/se7PhGh5ouJsHzF36Ngk+ZEL5lYadlcQfjZIHWvP2UfIH3HVEDHI2radGqXCfz0ETp1WTfDpO 7EgW6fXTElUH3UQ/ZMPOq4wPPMW6CYLJn5vFh2jAuGs/XxSj1Kd/MIPSiTKqZcm8y2I3RjJAt1cQp x0oiO3BrwGLdPlq2zGHDuYq1WdfsPZJfgVbKiyjIEyDnByrhOngx3dt/gsWum+RIzdh4bni62kC57 +8maGExg1pM9q43ZLkd35jJOoOsOOrWBd1IOerOHP5D0VgHrodtCQdrlRh2D58OfOU2YpcHe3eH+r L9RriV1Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1v0SVZ-00000008Kye-0xF5; Sun, 21 Sep 2025 22:26:13 +0000 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1v0SVV-00000008KyY-2aUn for kexec@bombadil.infradead.org; Sun, 21 Sep 2025 22:26:09 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=0Goc4fu4E5QtA9qLOcM+4h+EpWxYEBSIjsqPof2KABk=; b=eXHuVgdZPnG4LY9fvzsP9Thzot 7SaWdtBpIJZJ+ZMtycjRH8f62jRq439I7bIDyx/lEVq+2Y10XLWKT4YXi7uMdnYZoofhXR7UdOOOB RSmpSUJ7igwnEk+/VRLt6W6jicEw9dEBpykWNOAi5hSq+cGm/noOLpvNUmbGliqToIXvQ5yXENXp2 RhvcPu7pLZ1vqzz82SGYd/zFFjc43f6hYFhbKRjCSKqROT1b0A30axHs3tfmYRwL7WZZCmarTEiKL JkJqPsmNJcpyljqdklBvphzT8J935OBZoPhSuDwqpF7dZ38OGrRXbJC50KHrwCVSBrEm3TWxEt6d5 dCR4URDA==; Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1v0SVR-0000000COjD-2G10; Sun, 21 Sep 2025 22:26:05 +0000 Date: Sun, 21 Sep 2025 23:26:05 +0100 From: Matthew Wilcox To: Jason Gunthorpe Cc: Jason Miu , Alexander Graf , Andrew Morton , Baoquan He , Changyuan Lyu , David Matlack , David Rientjes , Joel Granados , Marcos Paulo de Souza , Mario Limonciello , Mike Rapoport , Pasha Tatashin , Petr Mladek , "Rafael J . Wysocki" , Steven Chen , Yan Zhao , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC v1 0/4] Make KHO Stateless Message-ID: References: <20250917025019.1585041-1-jasonmiu@google.com> <20250917113609.GB1086830@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250917113609.GB1086830@nvidia.com> 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 Wed, Sep 17, 2025 at 08:36:09AM -0300, Jason Gunthorpe wrote: > On Tue, Sep 16, 2025 at 07:50:15PM -0700, Jason Miu wrote: > > This series transitions KHO from an xarray-based metadata tracking > > system with serialization to using page table like data structures > > that can be passed directly to the next kernel. > > > > The key motivations for this change are to: > > - Eliminate the need for data serialization before kexec. > > - Remove the former KHO state machine by deprecating the finalize > > and abort states. > > - Pass preservation metadata more directly to the next kernel via the FDT. > > > > The new approach uses a per-order page table structure (kho_order_table, > > kho_page_table, kho_bitmap_table) to mark preserved pages. The physical > > address of the root `kho_order_table` is passed in the FDT, allowing the > > next kernel to reconstruct the preserved memory map. > > It is not a "page table" structure, it is just a radix tree with bits > as the leaf. Sounds like the IDA data structure. Maybe that API needs to be enhanced for this use case, but surely using the same data structure would be a good thing?