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 8BBBCC2D1; Fri, 22 Aug 2025 17:02:20 +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=1755882140; cv=none; b=Qziv/BNaOnwcfj0KWV7sr6xHjMqXjN6olVdrWEWwir0DivwV/48rtgGCJX38obJ51eMv1yiR27JRIwFnm7L9QKptV1k16Fup9r6Lx8AMN2IVbImn1zxIS3v9nd8ZwoeDa6s6DSUPrBRaO22ie3hqzPkXbqLS40CzJtb2LhtCCSc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755882140; c=relaxed/simple; bh=N43GnKy17u3pJmuxA0B+CvRzCGT4IjO9pWdh50KAxp8=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=o+JK/CO8sbSnwmCSSoH1tDbcvxkQFBA2qk2wuQCgulwaFkcrAAmkdkpGSqJGlAlMowfI4a1bXL1+XKcV/o1umi84tY5HokDDyUJhfbqqrzsazQKkJAf/2kLI4EM8WKBO5J36Jsj4Jy4TYMf7Otn/MbEUTPA9YI7Wy4p0ty/t7Tc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=X/RxlEh5; 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="X/RxlEh5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E7EA9C4CEED; Fri, 22 Aug 2025 17:02:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755882140; bh=N43GnKy17u3pJmuxA0B+CvRzCGT4IjO9pWdh50KAxp8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=X/RxlEh56SJyKzLLReKVy9zMR7Rn10sDZ2qGXdgaqLeUy++5vRLbAaO8F1sq4dW3A FVPFAm1E1KDu+9/CVB8PArKdY0HRrXTU0L7mEy3QGm8oDmYlvLcPGrEnt/PdkJ5xtS WPwGxZiqHYuwlyrYRxRwfpMchkAzSUix0wgYLGwYkH8uFDFTTyuMLp6fHc+1uXHfs8 s+X5+H1F8hdQ3OyIBGTgvD5OcC7RDayM3+Gr4vyGqAtfAsaEK49eudKcHbm56kC8gk 8jVNP2cdHpsMgjezsa0xbQw1c8LogFjCAJQgvfQ9Um93+KYDxx0kQzjtsDqYPIARCs dvKAxgTXqd2AA== From: SeongJae Park To: David Hildenbrand Cc: SeongJae Park , 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 , Mike Rapoport , 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 Date: Fri, 22 Aug 2025 10:02:17 -0700 Message-Id: <20250822170217.53169-1-sj@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250821200701.1329277-2-david@redhat.com> References: Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Thu, 21 Aug 2025 22:06:27 +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: SeongJae Park Thanks, SJ [...]