From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 593961B87EB; Fri, 16 May 2025 15:35:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747409729; cv=none; b=Il/6LyHztwpQZ6jWbpSVy92cuqDakViu1BzeSa6+9GTzP/EG3LqjfnW8oxguuM4QgmfZsSlqwvhHyYcuLbh4Ng6PBD0s3pk55Lbeh0n5iIDnTRbCVKAMIAgjQV+J2HPqsrzGkH1CiiiUKIe2D7cnHIKZwo8RWm/QLT56R0NNGFo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747409729; c=relaxed/simple; bh=tFBuEkfpTZDqLAksOlNvQnNL7DfHD68oh+9DLHIsuks=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JAdOwviyIjquJzrUUNbcpITZ2+vrOVXKoKdhkEmn5CBZQ3Sd+OT/1EFJhH3L0dc6OUxkj2zED8QjmqZIqJ/sWsUJWajS3/3MmqIM3p3TqttpMVJWyu6guFq0DWUI0lZNksB0byyxZDIUrcvzngJOo0WBfHFRKBz0UQx5TnEriB4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GjOgxn5L; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="GjOgxn5L" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C10FFC4CEE4; Fri, 16 May 2025 15:35:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747409728; bh=tFBuEkfpTZDqLAksOlNvQnNL7DfHD68oh+9DLHIsuks=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=GjOgxn5L6HlZB4ZnV59WnZgXYTasRydElhhX/90ByVYGKA645uJNUCcwDN1MkudLW I385G8yrdoUqBTB0XqhZqvllLe2wsxKZjeRnR4KKbO5HXWEfFyqn/4NEX62m0tqr/2 aaOKx3eiTkuC/4G20XNhpblZv3nPfyzyk3l18ZDrDVQMEFsB0/RWFkbX3F/v2Jp5Tz //XKYXg7JDq5PbYSI7NgiwkCIInbZ/e9i8+oMQqpKOd9qksPul59oxrToC359hYxXt UPGYCcJgt9BB305oJmHH+WHc/mOTeuaHgmYWMsjUit2gy5ooPaGl9bgUaj6Ya5Pojs Q03v2FKgO1BXg== Date: Fri, 16 May 2025 17:35:21 +0200 From: Ingo Molnar To: Dave Hansen Cc: "Kirill A. Shutemov" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Jonathan Corbet , Andy Lutomirski , Peter Zijlstra , Ard Biesheuvel , Jan Kiszka , Kieran Bingham , Michael Roth , Rick Edgecombe , Brijesh Singh , Sandipan Das , Juergen Gross , Tom Lendacky , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-efi@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCHv3 2/4] x86/64/mm: Make SPARSEMEM_VMEMMAP the only memory model Message-ID: References: <20250516123306.3812286-1-kirill.shutemov@linux.intel.com> <20250516123306.3812286-3-kirill.shutemov@linux.intel.com> <30570ca0-8da4-4ebc-84d6-0a4badfb7154@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: * Dave Hansen wrote: > On 5/16/25 07:08, Ingo Molnar wrote: > >> And is there any value to support !SPARSEMEM_VMEMMAP? > > Not really IMHO: > > > > .config.opensuse.default: CONFIG_SPARSEMEM_VMEMMAP_ENABLE=y > > .config.ubuntu.localinstall: CONFIG_SPARSEMEM_VMEMMAP_ENABLE=y > > .config.fedora.generic: CONFIG_SPARSEMEM_VMEMMAP_ENABLE=y > > .config.rhel.generic: CONFIG_SPARSEMEM_VMEMMAP_ENABLE=y > > I look at the distro configs all the time as well. > > But let's also not forget that none of these have lockdep turned on, Not actually true, quite a few distro debug kernel packages have lockdep on, and it's often enabled in internal QA rigs as well. Not so SPARSEMEM_VMEMMAP... > [...] and we don't want to toss out lockdep support on x86, for > example. ;) That's an apples to oranges comparison: - SPARSEMEM_VMEMMAP is always enabled, in standard and debug kernels as well. - lockdep is disabled in standard kernels, enabled in debug kernels and very much relied on. Thanks, Ingo