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 20D54126BFF; Fri, 22 Aug 2025 15:09:24 +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=1755875365; cv=none; b=sG1qVCcUuLl0KzoCjme+qn/SjinG2+FsBXR1tJsGdR0mn1x+AaCdROW314zE4MZnes8szwv0TAJdEyMoq+El0+C8erf+JGBOhrPtjISPSvym0ueSqPBGPrMHmjzjbTm8zzRXBnks2u6gxre1tUE3hhQNpGn07qJUmdG9ulo+WJk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755875365; c=relaxed/simple; bh=BbeE+oYVvXyCl/P3cWovjJUaU7WzCVAlNkMT749qO5w=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Q/jj4KPmrWxMj7eeEPCEUngVMeh2TTZLGdOvg/dwwvAIOSEw5IIMXIcd91xT5Ynx2blXNERcmKnmG6bn+LF8nT0vo9Md2dfUEF1Xbz3JBLaJbbTkEjX8SGEk9b7EGM0WZbYk+gIHnmF2GuOuGoc6R/quAz/pR972dJ/ZngFA8M4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Prntf9uZ; 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="Prntf9uZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4DC2FC113D0; Fri, 22 Aug 2025 15:09:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755875364; bh=BbeE+oYVvXyCl/P3cWovjJUaU7WzCVAlNkMT749qO5w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Prntf9uZKZis/U/bJlHQFXtv4HnPV3FVBr1/P31JtBZdZlx8pNyYQrIV2U1OHL2Ph KWg0PSoWLWhirFvfgHCyLwMGddND32c/PoybCUWyTY4uJJaWAm3pqSnmsGRF97A6G4 VDGi/p4toQ5nig1708cGRPMAz3wCxoj5eCkSR54XvHPYG/bVMzGFIuTMu74kogSth9 uZBDebwYJugk9IlUMY2oDzjDlJybUXGUDToJl2tsj04xT1jSsHqLJwHeqPJg2mwSqm 1JhNQxwyrU8QnJ30mOJ/Iq/kXqrUNLLTQ0bAe831b6zLWD86rnmkM7tBokSIpXtEvj XiFVPUzX/IwAA== Date: Fri, 22 Aug 2025 18:09:03 +0300 From: Mike Rapoport To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, Huacai Chen , WANG Xuerui , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , "David S. Miller" , Andreas Larsson , Alexander Potapenko , Andrew Morton , Brendan Jackman , Christoph Lameter , Dennis Zhou , Dmitry Vyukov , dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, iommu@lists.linux.dev, io-uring@vger.kernel.org, Jason Gunthorpe , Jens Axboe , Johannes Weiner , John Hubbard , kasan-dev@googlegroups.com, kvm@vger.kernel.org, "Liam R. Howlett" , Linus Torvalds , linux-arm-kernel@axis.com, linux-arm-kernel@lists.infradead.org, linux-crypto@vger.kernel.org, linux-ide@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mips@vger.kernel.org, linux-mmc@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, Lorenzo Stoakes , Marco Elver , Marek Szyprowski , Michal Hocko , Muchun Song , netdev@vger.kernel.org, Oscar Salvador , Peter Xu , Robin Murphy , Suren Baghdasaryan , Tejun Heo , virtualization@lists.linux.dev, Vlastimil Babka , wireguard@lists.zx2c4.com, x86@kernel.org, Zi Yan Subject: Re: [PATCH RFC 01/35] mm: stop making SPARSEMEM_VMEMMAP user-selectable Message-ID: References: <20250821200701.1329277-1-david@redhat.com> <20250821200701.1329277-2-david@redhat.com> Precedence: bulk X-Mailing-List: linux-crypto@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: <20250821200701.1329277-2-david@redhat.com> On Thu, Aug 21, 2025 at 10:06:27PM +0200, David Hildenbrand wrote: > In an ideal world, we wouldn't have to deal with SPARSEMEM without > SPARSEMEM_VMEMMAP, but in particular for 32bit SPARSEMEM_VMEMMAP is > considered too costly and consequently not supported. > > However, if an architecture does support SPARSEMEM with > SPARSEMEM_VMEMMAP, let's forbid the user to disable VMEMMAP: just > like we already do for arm64, s390 and x86. > > So if SPARSEMEM_VMEMMAP is supported, don't allow to use SPARSEMEM without > SPARSEMEM_VMEMMAP. > > This implies that the option to not use SPARSEMEM_VMEMMAP will now be > gone for loongarch, powerpc, riscv and sparc. All architectures only > enable SPARSEMEM_VMEMMAP with 64bit support, so there should not really > be a big downside to using the VMEMMAP (quite the contrary). > > This is a preparation for not supporting > > (1) folio sizes that exceed a single memory section > (2) CMA allocations of non-contiguous page ranges > > in SPARSEMEM without SPARSEMEM_VMEMMAP configs, whereby we > want to limit possible impact as much as possible (e.g., gigantic hugetlb > page allocations suddenly fails). > > Cc: Huacai Chen > Cc: WANG Xuerui > Cc: Madhavan Srinivasan > Cc: Michael Ellerman > Cc: Nicholas Piggin > Cc: Christophe Leroy > Cc: Paul Walmsley > Cc: Palmer Dabbelt > Cc: Albert Ou > Cc: Alexandre Ghiti > Cc: "David S. Miller" > Cc: Andreas Larsson > Signed-off-by: David Hildenbrand Acked-by: Mike Rapoport (Microsoft) > --- > mm/Kconfig | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/mm/Kconfig b/mm/Kconfig > index 4108bcd967848..330d0e698ef96 100644 > --- a/mm/Kconfig > +++ b/mm/Kconfig > @@ -439,9 +439,8 @@ config SPARSEMEM_VMEMMAP_ENABLE > bool > > config SPARSEMEM_VMEMMAP > - bool "Sparse Memory virtual memmap" > + def_bool y > depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE > - default y > help > SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise > pfn_to_page and page_to_pfn operations. This is the most > -- > 2.50.1 > -- Sincerely yours, Mike.