From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 551FE34F482 for ; Mon, 1 Sep 2025 15:07:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756739260; cv=none; b=mzx0bBHFXE3YPUIFQU73falJ0nvWKRm6h0DUv3GTdO6eXVyaGRYEW+ndQnyXJRfyAqzoRprajXlFOQAXSNe/czwvopmlIIaf4SY3kBlb6R5enEUJJhHpdCbT9JH3JZ+6iSNJcTCFtUyvuoMFZL/ryqDatkkZ0T03eg0ggcMIl+4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756739260; c=relaxed/simple; bh=vpP0rsuJYmmzYFvUEq/GBYJyw49cOYdlW9eiVdEiwYw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GBywmvEyitZiXyIMDNHHSOeAB/hEgl0mrUoUHKS8mbHvrGonYETdbd26SfQxc61otgq4pkSt/oNOEWiWlWPKhSfmnQULbULHBjwHkWc1pLNSlCgxvvloW1jHwcEbW42MhllaMCY4IgoSQhaqSb6dWEOcG7F7XHNq1VlLyEzOSCk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=SZP6Otuj; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="SZP6Otuj" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1756739257; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1uoE6NXhltHN+7rLv53vXfhLviFP/GMqcI5NGlTVFxQ=; b=SZP6OtujtqNfh0T6owmQyAVDMw7ZRMYCIatR22bEBZih935fz+q4zeUxgMRmqKVJrKtw9M 9rajmUxkZy0L/RnCZiqco+fypopZ+CzSRnQhYYXt+AmBwN9UrkAuIafzS57K9uSeJWXwuY AhoPfo5zN0noluTiHXC6FOBwXHjurSY= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-458-Vu95gNDhN86FCvXuoQpXFg-1; Mon, 01 Sep 2025 11:07:34 -0400 X-MC-Unique: Vu95gNDhN86FCvXuoQpXFg-1 X-Mimecast-MFC-AGG-ID: Vu95gNDhN86FCvXuoQpXFg_1756739249 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 609CF195608B; Mon, 1 Sep 2025 15:07:29 +0000 (UTC) Received: from t14s.fritz.box (unknown [10.22.88.45]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 9DFF318003FC; Mon, 1 Sep 2025 15:07:15 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: David Hildenbrand , Zi Yan , "Mike Rapoport (Microsoft)" , Wei Yang , Lorenzo Stoakes , "Liam R. Howlett" , 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, 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, 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 Subject: [PATCH v2 11/37] mm: limit folio/compound page sizes in problematic kernel configs Date: Mon, 1 Sep 2025 17:03:32 +0200 Message-ID: <20250901150359.867252-12-david@redhat.com> In-Reply-To: <20250901150359.867252-1-david@redhat.com> References: <20250901150359.867252-1-david@redhat.com> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 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. Reviewed-by: Zi Yan Acked-by: Mike Rapoport (Microsoft) Reviewed-by: Wei Yang Reviewed-by: Lorenzo Stoakes Reviewed-by: Liam R. Howlett Signed-off-by: David Hildenbrand --- 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..2dee79fa2efcf 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 (e.g., hugetlb, dax). + */ +#define MAX_FOLIO_ORDER PUD_ORDER #endif #define MAX_FOLIO_NR_PAGES (1UL << MAX_FOLIO_ORDER) -- 2.50.1