From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pegase2.c-s.fr (pegase2.c-s.fr [93.17.235.10]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 3808626B97E; Thu, 9 Oct 2025 08:20:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=93.17.235.10 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759998038; cv=none; b=cWmqDwSIO66TD1ZBMCMVgwKNRiWvloggY2coS4at9fXePtT8MOw51LxiJ3XQhX92RBO2kvrWeULSy1z11gjjqEX91CtHVp9hyl4m1xDT1NTmCwNYMEusO/TBwx94MyoKt/W2QGQylRwQ9Se7lj6O6UvccDXgDB4BWi7iECcMy7E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759998038; c=relaxed/simple; bh=r4j7KL3ZDY2ItBlX7tAcF4DYZ7j4P2ykR08zNx+Sdac=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=pUAvLRyzDeAVWYHKe7DJyGMf6wyYuSYTyZSEMDvDgsCP1+IwyuQ9+Ssk/26PD+pRfNG8XC8eUSzEFd1W0/YGDQEecLLr6zS8P8rnaictPJvLiO1Z56HTtRRundgDFDYU9IMVfjP+mDDcMRos/Py0Xz21XRAFFzIZ+Z+zWmqiIAk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=csgroup.eu; spf=pass smtp.mailfrom=csgroup.eu; arc=none smtp.client-ip=93.17.235.10 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=csgroup.eu Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=csgroup.eu Received: from localhost (mailhub4.si.c-s.fr [172.26.127.67]) by localhost (Postfix) with ESMTP id 4cj2Td0Mj6z9sSL; Thu, 9 Oct 2025 10:04:37 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from pegase2.c-s.fr ([172.26.127.65]) by localhost (pegase2.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id qQ36Dhni13kk; Thu, 9 Oct 2025 10:04:36 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase2.c-s.fr (Postfix) with ESMTP id 4cj2Tc5kJ8z9sSC; Thu, 9 Oct 2025 10:04:36 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id A8FDF8B770; Thu, 9 Oct 2025 10:04:36 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id CnXkw3FAfnqR; Thu, 9 Oct 2025 10:04:36 +0200 (CEST) Received: from [192.168.235.99] (unknown [192.168.235.99]) by messagerie.si.c-s.fr (Postfix) with ESMTP id AE04F8B76D; Thu, 9 Oct 2025 10:04:34 +0200 (CEST) Message-ID: Date: Thu, 9 Oct 2025 10:04:34 +0200 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: (bisected) [PATCH v2 08/37] mm/hugetlb: check for unreasonable folio sizes when registering hstate To: David Hildenbrand , linux-kernel@vger.kernel.org Cc: Zi Yan , 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 , 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, "linuxppc-dev@lists.ozlabs.org" References: <20250901150359.867252-1-david@redhat.com> <20250901150359.867252-9-david@redhat.com> <3e043453-3f27-48ad-b987-cc39f523060a@csgroup.eu> From: Christophe Leroy Content-Language: fr-FR In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Le 09/10/2025 à 09:22, David Hildenbrand a écrit : > On 09.10.25 09:14, Christophe Leroy wrote: >> Hi David, >> >> Le 01/09/2025 à 17:03, David Hildenbrand a écrit : >>> diff --git a/mm/hugetlb.c b/mm/hugetlb.c >>> index 1e777cc51ad04..d3542e92a712e 100644 >>> --- a/mm/hugetlb.c >>> +++ b/mm/hugetlb.c >>> @@ -4657,6 +4657,7 @@ static int __init hugetlb_init(void) >>>        BUILD_BUG_ON(sizeof_field(struct page, private) * BITS_PER_BYTE < >>>                __NR_HPAGEFLAGS); >>> +    BUILD_BUG_ON_INVALID(HUGETLB_PAGE_ORDER > MAX_FOLIO_ORDER); >>>        if (!hugepages_supported()) { >>>            if (hugetlb_max_hstate || default_hstate_max_huge_pages) >>> @@ -4740,6 +4741,7 @@ void __init hugetlb_add_hstate(unsigned int order) >>>        } >>>        BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE); >>>        BUG_ON(order < order_base_2(__NR_USED_SUBPAGE)); >>> +    WARN_ON(order > MAX_FOLIO_ORDER); >>>        h = &hstates[hugetlb_max_hstate++]; >>>        __mutex_init(&h->resize_lock, "resize mutex", &h->resize_key); >>>        h->order = order; > > We end up registering hugetlb folios that are bigger than > MAX_FOLIO_ORDER. So we have to figure out how a config can trigger that > (and if we have to support that). > MAX_FOLIO_ORDER is defined as: #ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE #define MAX_FOLIO_ORDER PUD_ORDER #else #define MAX_FOLIO_ORDER MAX_PAGE_ORDER #endif MAX_PAGE_ORDER is the limit for dynamic creation of hugepages via /sys/kernel/mm/hugepages/ but bigger pages can be created at boottime with kernel boot parameters without CONFIG_ARCH_HAS_GIGANTIC_PAGE: hugepagesz=64m hugepages=1 hugepagesz=256m hugepages=1 Gives: HugeTLB: registered 1.00 GiB page size, pre-allocated 0 pages HugeTLB: 0 KiB vmemmap can be freed for a 1.00 GiB page HugeTLB: registered 64.0 MiB page size, pre-allocated 1 pages HugeTLB: 0 KiB vmemmap can be freed for a 64.0 MiB page HugeTLB: registered 256 MiB page size, pre-allocated 1 pages HugeTLB: 0 KiB vmemmap can be freed for a 256 MiB page HugeTLB: registered 4.00 MiB page size, pre-allocated 0 pages HugeTLB: 0 KiB vmemmap can be freed for a 4.00 MiB page HugeTLB: registered 16.0 MiB page size, pre-allocated 0 pages HugeTLB: 0 KiB vmemmap can be freed for a 16.0 MiB page Christophe