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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C0912CA0FE8 for ; Sun, 24 Aug 2025 13:24:55 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0CA4E8E0009; Sun, 24 Aug 2025 09:24:55 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 07B928E0001; Sun, 24 Aug 2025 09:24:55 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ED31A8E0009; Sun, 24 Aug 2025 09:24:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id D8B768E0001 for ; Sun, 24 Aug 2025 09:24:54 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 84EF81D3192 for ; Sun, 24 Aug 2025 13:24:54 +0000 (UTC) X-FDA: 83811721308.15.EB6C91F Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf24.hostedemail.com (Postfix) with ESMTP id C680F18000A for ; Sun, 24 Aug 2025 13:24:52 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=SquWihWK; spf=pass (imf24.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1756041893; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=sTgVSQ/agc49mf+WMVj/m/VVuvPKZX5i68p4dayRd8w=; b=UukvlV3pQseopq2q3IAkd//sDeXWdGOzpeLyKPGzUL2tZQAYkduV0jVP7reFSFgjcLClFF sQR3yS+VE5FYIxYTFOEPNfUf/OrIhAGg2vyBsLgmNh0+4TDhtROkXSKNGB+KfVgQT9cDld OknJZp0l1TCxGYIM5yLWMBhit1EICdQ= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=SquWihWK; spf=pass (imf24.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1756041893; a=rsa-sha256; cv=none; b=5U+/LyRXUDoj5qyLhDYtA3mGX3dH+i6atKMT96e49SVO55wRpaYKMZLGZiPS9IBM/AC3Sz iIDJCPG4hjEy54Ay+fefgNMFYIHJ2YbgQNGSMBhp2Ej6W2MBFg8+gKByfNSIa6ex4opDSL yigu7SItsAI0aIXhmRZdplTs9ICgsdo= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 7D3EC43442; Sun, 24 Aug 2025 13:24:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B4638C4CEEB; Sun, 24 Aug 2025 13:24:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756041880; bh=ULWSWvx5qOQocuXhhEVwmUdZJ/jQrpo8zzXV1kr+XYk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=SquWihWK3f+VpRPVHREvb/KU1Ip2U18TP7N1MuJITOAx4rQrPZH3cvqtkOP5SvK7q i6NO1TPVUbZk8RWkAk3LTCsFqBTBZ14HIKev8nasvhFuIsLkIUiO3cKzio2Q51II/F wyed5FtAlddWEWPif7U0YGP0VU7Jz0WnTx8oiBRZXCVwF7SJXztCvl7h61L8oudm/m ZzJcPQiQ6a3vkdslZGaL+map5bzuxrOH69hNlp4a8gDkADVHKqlXnjP6H9fUKUPAle G5RP+5YSDJFPCZAOfsIK30ngRx5fl+uNMhMZuFtvohYRU68gjsyw/nUrRlnisE/5CR 1GDLoGVBUCvXA== Date: Sun, 24 Aug 2025 16:24:23 +0300 From: Mike Rapoport To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, 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 12/35] mm: limit folio/compound page sizes in problematic kernel configs Message-ID: References: <20250821200701.1329277-1-david@redhat.com> <20250821200701.1329277-13-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250821200701.1329277-13-david@redhat.com> X-Stat-Signature: 3u635bh8qc519bser9fh7bmtophkg5u5 X-Rspam-User: X-Rspamd-Queue-Id: C680F18000A X-Rspamd-Server: rspam05 X-HE-Tag: 1756041892-359013 X-HE-Meta: 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 cf8i6TwZ W0iJB+Z9klgE3VeZPrr/xb5TNn/9IIhM4lYnYhPbh1gJQkG1mvWQnC2adFgshsKYFEWGliYF7wr+IgzeFShTTZ80cWyWVILfwR30pePU7SHyu8aHPFv8/uX6tVqLQiXIDfAFWHZnjKDbXv1U+KKctdcn7ZPh71tix8KgIZpLAsGr08PieRkl4rc4brxV4nq9ElrflJukDdJaN5EXH5gl8zh0yfBhbGogndm5jrl7GBtTvrTUn160wqoqL5zMG0TbRbJ4tyM3mXOvUNwOuKyMDGxqHqDXi6xxvvgFd1LU1D7BngnQfpu02LbvgoN0+jaesfdRSZtO5ZNuG6qI= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Aug 21, 2025 at 10:06:38PM +0200, David Hildenbrand wrote: > Let's limit the maximum folio size in problematic kernel config where > the memmap is allocated per memory section (SPARSEMEM without > SPARSEMEM_VMEMMAP) to a single memory section. > > Currently, only a single architectures supports ARCH_HAS_GIGANTIC_PAGE > but not SPARSEMEM_VMEMMAP: sh. > > Fortunately, the biggest hugetlb size sh supports is 64 MiB > (HUGETLB_PAGE_SIZE_64MB) and the section size is at least 64 MiB > (SECTION_SIZE_BITS == 26), so their use case is not degraded. > > As folios and memory sections are naturally aligned to their order-2 size > in memory, consequently a single folio can no longer span multiple memory > sections on these problematic kernel configs. > > nth_page() is no longer required when operating within a single compound > page / folio. > > Signed-off-by: David Hildenbrand Acked-by: Mike Rapoport (Microsoft) > --- > include/linux/mm.h | 22 ++++++++++++++++++---- > 1 file changed, 18 insertions(+), 4 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 77737cbf2216a..48a985e17ef4e 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -2053,11 +2053,25 @@ static inline long folio_nr_pages(const struct folio *folio) > return folio_large_nr_pages(folio); > } > > -/* Only hugetlbfs can allocate folios larger than MAX_ORDER */ > -#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE > -#define MAX_FOLIO_ORDER PUD_ORDER > -#else > +#if !defined(CONFIG_ARCH_HAS_GIGANTIC_PAGE) > +/* > + * We don't expect any folios that exceed buddy sizes (and consequently > + * memory sections). > + */ > #define MAX_FOLIO_ORDER MAX_PAGE_ORDER > +#elif defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) > +/* > + * Only pages within a single memory section are guaranteed to be > + * contiguous. By limiting folios to a single memory section, all folio > + * pages are guaranteed to be contiguous. > + */ > +#define MAX_FOLIO_ORDER PFN_SECTION_SHIFT > +#else > +/* > + * There is no real limit on the folio size. We limit them to the maximum we > + * currently expect. > + */ > +#define MAX_FOLIO_ORDER PUD_ORDER > #endif > > #define MAX_FOLIO_NR_PAGES (1UL << MAX_FOLIO_ORDER) > -- > 2.50.1 > -- Sincerely yours, Mike.