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 7E76D23D7DB; Sat, 23 Aug 2025 09:00:08 +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=1755939608; cv=none; b=dXrcrm8x496Q3BhRjfrSmPxOp10jyaAinCDl3BOpaKl4l+/KIdn03FlNPqs4ilQwhpbkb1umSvHME8OQCqxgTBWu6J9I6ZNqPiOMmDX8eAlzyh0aihrJAqHvO4mdNnbvAhsTDi8I3jWTrPbOxPZH6geh1gylc1FrKylxVqK3u/M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755939608; c=relaxed/simple; bh=aU4s6rL8qphUf3ASSPtkvFhSbnF7KQL/5p/AkB6ZkD0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=eUiIZIYSWxXBZ5vRjGUYEEVuNZoE907Mj7xmlK0WI1X4JtxeY1DqQqbAdzGyW4/Z7FamBh1rsXSz4dWNDT3q2Kr3UKbvUHrj1Iy0hTwIUfXEXhZ3TQ/mFBTJvm62+sgrlBm20EoYf5Qy3vfRayfDYY7ra+nyEcnfmQZeCMVMYks= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rOGkWtsU; 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="rOGkWtsU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F35E6C113D0; Sat, 23 Aug 2025 08:59:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755939608; bh=aU4s6rL8qphUf3ASSPtkvFhSbnF7KQL/5p/AkB6ZkD0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rOGkWtsURQmqeVJWZZ8QU1TwZHK57H1RHXwc/i48rhECw+oAVRa4mF0zfqNM3aJ7b K4ufsfNlCAWHsLgknGRRJAM8fAg49ifByU7aHcJpd60KD5n2ftLsVEjekOSHSO2hKf TyNgVi/IP/sZ+Zv1HQC39pwpdaVXtYVat6Ea2uqdZXF6QBRAllDzvBMajMv+E6mXfL wV6BxOvsD2NYhNSk4hF0URYans98VMn0JY+kTDajsHLCy41MHKhsR0ynwpYDfvi23F uDIHwC7s5hdPOSqfKNvqn2djgrkhoLcYMLwZ0RX2xL3FelT1nsv2lD+CEaDl2f3oOX wFjm0sW7YW4bQ== Date: Sat, 23 Aug 2025 11:59:50 +0300 From: Mike Rapoport To: David Hildenbrand Cc: Mika =?iso-8859-1?Q?Penttil=E4?= , 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 10/35] mm/hugetlb: cleanup hugetlb_folio_init_tail_vmemmap() Message-ID: References: <20250821200701.1329277-1-david@redhat.com> <20250821200701.1329277-11-david@redhat.com> <9156d191-9ec4-4422-bae9-2e8ce66f9d5e@redhat.com> <7077e09f-6ce9-43ba-8f87-47a290680141@redhat.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <7077e09f-6ce9-43ba-8f87-47a290680141@redhat.com> On Fri, Aug 22, 2025 at 08:24:31AM +0200, David Hildenbrand wrote: > On 22.08.25 06:09, Mika Penttilä wrote: > > > > On 8/21/25 23:06, David Hildenbrand wrote: > > > > > All pages were already initialized and set to PageReserved() with a > > > refcount of 1 by MM init code. > > > > Just to be sure, how is this working with MEMBLOCK_RSRV_NOINIT, where MM is supposed not to > > initialize struct pages? > > Excellent point, I did not know about that one. > > Spotting that we don't do the same for the head page made me assume that > it's just a misuse of __init_single_page(). > > But the nasty thing is that we use memblock_reserved_mark_noinit() to only > mark the tail pages ... And even nastier thing is that when CONFIG_DEFERRED_STRUCT_PAGE_INIT is disabled struct pages are initialized regardless of memblock_reserved_mark_noinit(). I think this patch should go in before your updates: diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 753f99b4c718..1c51788339a5 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -3230,6 +3230,22 @@ int __alloc_bootmem_huge_page(struct hstate *h, int nid) return 1; } +/* + * Tail pages in a huge folio allocated from memblock are marked as 'noinit', + * which means that when CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled their + * struct page won't be initialized + */ +#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT +static void __init hugetlb_init_tail_page(struct page *page, unsigned long pfn, + enum zone_type zone, int nid) +{ + __init_single_page(page, pfn, zone, nid); +} +#else +static inline void hugetlb_init_tail_page(struct page *page, unsigned long pfn, + enum zone_type zone, int nid) {} +#endif + /* Initialize [start_page:end_page_number] tail struct pages of a hugepage */ static void __init hugetlb_folio_init_tail_vmemmap(struct folio *folio, unsigned long start_page_number, @@ -3244,7 +3260,7 @@ static void __init hugetlb_folio_init_tail_vmemmap(struct folio *folio, for (pfn = head_pfn + start_page_number; pfn < end_pfn; pfn++) { struct page *page = pfn_to_page(pfn); - __init_single_page(page, pfn, zone, nid); + hugetlb_init_tail_page(page, pfn, zone, nid); prep_compound_tail((struct page *)folio, pfn - head_pfn); ret = page_ref_freeze(page, 1); VM_BUG_ON(!ret); > Let me revert back to __init_single_page() and add a big fat comment why > this is required. > > Thanks! -- Sincerely yours, Mike.