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 19FA619DF62; Mon, 25 Aug 2025 14:59:39 +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=1756133980; cv=none; b=qYr26YGLLBA2DF4CLgY2tlsaN0Ubql442KwVdVO35eaU0X32lbAff34a9hYhkx1tkNYID0c8o0FcFzMaOKLPYtjMewHyzgu1Td2+UxOw+MUR51xgsDx8T1h0kWvmhS9a5kyXFfcmDiG6So2t7v8s4Fv2CKK6IV9PgXbQ+4qvsU8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756133980; c=relaxed/simple; bh=YtWwiemXxXk/HndwfafEfgJsQeylyFu02jnoMvbgzgo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=YGCWp0A5VhuY724yB1LV0CFqLv+ny+x6qWXamyNo5yg00vIkF+lSv0u2Wdf1C2kRSxZBf5dNE1VlD2WIrODCGqRhJQQSOKfclLJKjrZutKBLumd9uYkJ+LnPexySPu11/BFElss08JOM39geZsUPYQ5fwBprxtfZ5uW9O2euhbs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Jn0AZo3p; 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="Jn0AZo3p" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6B3D6C4CEED; Mon, 25 Aug 2025 14:59:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756133979; bh=YtWwiemXxXk/HndwfafEfgJsQeylyFu02jnoMvbgzgo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Jn0AZo3pPFK0BugUL3OMCDpCV1HmeNy40TLdNKtLX5SypUoRptbAF9EKk4ejmZPkz 4+fhto2i95Q8o+P1Az66DJeNk8sJ/NyNwPVZIk6s6vBe389Ho9bI4oPnQEWOp80T7O GtLnp1xpVgMb/AC15WB27oS0HJcJwkR6UUktQVbU3ti8iXBP/sjXLozRWAuvgf0GjM wZgTeBgQn1M3OOuOkCDIwQMCPIaP4blPKHTb9cXNDnLZlHu07Wyh1OfkyGZAnS83zw dhcVTO4etdblD/32knv8disDXUulJuw7B97TzcOXKyT3A66aD23GWc4jfTztl6wlSw r5yMDLTA1mfKw== Date: Mon, 25 Aug 2025 17:59:22 +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: io-uring@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: On Mon, Aug 25, 2025 at 04:38:03PM +0200, David Hildenbrand wrote: > On 25.08.25 16:32, Mike Rapoport wrote: > > On Mon, Aug 25, 2025 at 02:48:58PM +0200, David Hildenbrand wrote: > > > On 23.08.25 10:59, Mike Rapoport wrote: > > > > 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: > > > > > > Shouldn't we fix this in memblock code? > > > > > > Hacking around that in the memblock_reserved_mark_noinit() user sound wrong > > > -- and nothing in the doc of memblock_reserved_mark_noinit() spells that > > > behavior out. > > > > We can surely update the docs, but unfortunately I don't see how to avoid > > hacking around it in hugetlb. > > Since it's used to optimise HVO even further to the point hugetlb open > > codes memmap initialization, I think it's fair that it should deal with all > > possible configurations. > > Remind me, why can't we support memblock_reserved_mark_noinit() when > CONFIG_DEFERRED_STRUCT_PAGE_INIT is disabled? When CONFIG_DEFERRED_STRUCT_PAGE_INIT is disabled we initialize the entire memmap early (setup_arch()->free_area_init()), and we may have a bunch of memblock_reserved_mark_noinit() afterwards > -- > Cheers > > David / dhildenb > -- Sincerely yours, Mike.