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]) by smtp.lore.kernel.org (Postfix) with ESMTP id BA56AC54EBD for ; Sun, 8 Jan 2023 16:51:07 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 07DF28E0002; Sun, 8 Jan 2023 11:51:07 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 02E028E0001; Sun, 8 Jan 2023 11:51:06 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E39008E0002; Sun, 8 Jan 2023 11:51:06 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id D364E8E0001 for ; Sun, 8 Jan 2023 11:51:06 -0500 (EST) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 97A04A04F1 for ; Sun, 8 Jan 2023 16:51:06 +0000 (UTC) X-FDA: 80332221732.22.EC2405D Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by imf01.hostedemail.com (Postfix) with ESMTP id D9A4640006 for ; Sun, 8 Jan 2023 16:51:04 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=BtebHmmq; spf=pass (imf01.hostedemail.com: domain of rppt@kernel.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1673196665; 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=kWGPtjdb0i7Eewgft4eB7xLHOFmG9M2Gti1bU6M7HCk=; b=LvzZ3ZaTB90QNS8nY8Neq/c2ExniOAtAEdiiIqXPLOh9d5arsUQItUCk+BV2lOZ3/5l3z3 IFC50GsyaprF88EQy57kUiKrwV4KuMz4vXUyPtdkxVT+iKvb00LImiCeU3ukrtrwS8+Qme umi2IykQp1uU7+qceNm2x5ZGMrxPDdw= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=BtebHmmq; spf=pass (imf01.hostedemail.com: domain of rppt@kernel.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1673196665; a=rsa-sha256; cv=none; b=625BFP/tcpWkP7qtk6OE4VIeWzAS4s8yUFTiV7af4iMzv/el/q4uFJFo1Uppzi16Xrx6oE SfkHaO0i3gCeGdHlUlIaKtRCljf6FC1uJpWIdNTkOsiSbazAodk72LBfIolrLMCB5PD+Ki Hz6077LGeanKzuXahWLpz1AJqSpkeBc= Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 323FCB80B56; Sun, 8 Jan 2023 16:51:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8226CC433D2; Sun, 8 Jan 2023 16:50:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1673196661; bh=Qe/eO9zN1m73qj2kFmidTrQ9cFufjLEB3fslciiYZs4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=BtebHmmqrThyQ1nswpd1Xn9WtSyyL3ea2mf1WfLNjmglnsJNbDmuWJ6ko1LEgYmXC PZ4OT6gM2JbWCL67GifNyHhySNe7V3TQ5y8K8/YQHKflYi5khRP52dymRfHWnBcPtk y8YO9CM10bkbTkpZABs3BAQgkdk3nGyPPT97DsyFmfiqF4rSQfVCX1e8HCPaOcsVek bPbh2R+rcX57lUzndqdcxEgM1wFtyKEMjanSZcTBDNzw+cm1L4KCX6rpWr+bRXvPBJ uKS13hWoKkLm8qUTBCwlyNwENMJJgH4SauhiBw0fDEQZfTCVQbA589gPZAZfIOnz0O owXuZ6ha7SgoA== Date: Sun, 8 Jan 2023 18:50:45 +0200 From: Mike Rapoport To: Aaron Thompson Cc: linux-mm@kvack.org, "H. Peter Anvin" , Alexander Potapenko , Andrew Morton , Andy Shevchenko , Ard Biesheuvel , Borislav Petkov , Darren Hart , Dave Hansen , David Rientjes , Dmitry Vyukov , Ingo Molnar , Marco Elver , Thomas Gleixner , kasan-dev@googlegroups.com, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH v3 1/1] mm: Always release pages to the buddy allocator in memblock_free_late(). Message-ID: References: <20230106222222.1024-1-dev@aaront.org> <01010185892de53e-e379acfb-7044-4b24-b30a-e2657c1ba989-000000@us-west-2.amazonses.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <01010185892de53e-e379acfb-7044-4b24-b30a-e2657c1ba989-000000@us-west-2.amazonses.com> X-Stat-Signature: da113koshqiquxt3aoeog3w8ftwq1anj X-Rspam-User: X-Rspamd-Queue-Id: D9A4640006 X-Rspamd-Server: rspam06 X-HE-Tag: 1673196664-528812 X-HE-Meta: U2FsdGVkX1/T/2xKt862dUjauTq8Xe1FHlCfrD9fggJYnctaiXH6tU3RVfs/2gUmG8G1iha/qq3Tgwhy7rvEqWgavf3fveusOLZdq6O7CdLULNthF4rrJYgEwWDvBcPHrkvUXy2f0q0wnXFN69lunxpn+Cr9y0MrURxd3n1B3Q+HO42peO/En1SXEdj1m6sH5jQzhFjuQx+OIuWqTiKzkK9x93tCW8sVbXfy2JR5KCna6oct2OFBFfk37/BGUgUEpsCHldyMHCwegWdNCqE/gIDJPRbu+0QdvJ9Z1pMPC8j7RfkaewfO0u+2uFKvJ/eiGztq6VjU0/hsZp70YJ8d2gQKE7Ccxct27DAnBAuGCHM6mHwCGaXWtfJgp3rHqdIKOKd11bU6gHFeT5tienpTVG+QmGlBa/+EQDmov2cP4sIosfZOkc095seHVIRRPj5cTIQ6/6nTLk+XXrsHw5GbvtQc/yzveV3RG65eHJlGZNgFdqJo2uaNZ5FDvfw3Bsz22xcQC4xTev77RRMVjfy3Mr2x4nltcZSvgZPEe7Ica4XdWNsdBMkH3FUxiV9gcBcCKmjtmenpv1KQd18f1uLgwi4vExib3PRpdZXu33JEATDOEKpvdo0iKa+zXVbN4SEol5wMYFqlLQ//D5R+kappRrh3yuo6txDHghqBhRjL3PmsqBILddE31OU7dxszehuZluCGXkR3uKSt5oc5dseZ7vi5ETwExhjsjPZ5oSH1vSlm5e0adfRwGu1ZBMqou1JzN4tgnaDhic4C9ZjQC1GTLCsBX6n3D62pUU7LgAcprWfLl7l9GZiycp4arGskPCh7RAV/RYUU/Ssyn6s5UoTREAXfH38pr+fZdQGwiYiW8cNm5OUIeoZi6qTq1kAWVfOqHgiKIT/KyIc/u19LsRhdnbMAqnkUzxmrQMz+trlPcPQzaIWstGDnbQcuiI+tzp6Z4mXJ3Jb5vYlLw8PztEL +2kJ2BDP KI/dTscZgyiK9JMX49YHu7aJGB5bkmHpbhJ50cIn8jxfRkzn0SFJhGJP5kqkH5+iKaZdMNRr58GwaUi3EG0as2+imWg== 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: On Fri, Jan 06, 2023 at 10:22:44PM +0000, Aaron Thompson wrote: > If CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled, memblock_free_pages() > only releases pages to the buddy allocator if they are not in the > deferred range. This is correct for free pages (as defined by > for_each_free_mem_pfn_range_in_zone()) because free pages in the > deferred range will be initialized and released as part of the deferred > init process. memblock_free_pages() is called by memblock_free_late(), > which is used to free reserved ranges after memblock_free_all() has > run. All pages in reserved ranges have been initialized at that point, > and accordingly, those pages are not touched by the deferred init > process. This means that currently, if the pages that > memblock_free_late() intends to release are in the deferred range, they > will never be released to the buddy allocator. They will forever be > reserved. > > In addition, memblock_free_pages() calls kmsan_memblock_free_pages(), > which is also correct for free pages but is not correct for reserved > pages. KMSAN metadata for reserved pages is initialized by > kmsan_init_shadow(), which runs shortly before memblock_free_all(). > > For both of these reasons, memblock_free_pages() should only be called > for free pages, and memblock_free_late() should call __free_pages_core() > directly instead. > > One case where this issue can occur in the wild is EFI boot on > x86_64. The x86 EFI code reserves all EFI boot services memory ranges > via memblock_reserve() and frees them later via memblock_free_late() > (efi_reserve_boot_services() and efi_free_boot_services(), > respectively). If any of those ranges happens to fall within the > deferred init range, the pages will not be released and that memory will > be unavailable. > > For example, on an Amazon EC2 t3.micro VM (1 GB) booting via EFI: > > v6.2-rc2: > # grep -E 'Node|spanned|present|managed' /proc/zoneinfo > Node 0, zone DMA > spanned 4095 > present 3999 > managed 3840 > Node 0, zone DMA32 > spanned 246652 > present 245868 > managed 178867 > > v6.2-rc2 + patch: > # grep -E 'Node|spanned|present|managed' /proc/zoneinfo > Node 0, zone DMA > spanned 4095 > present 3999 > managed 3840 > Node 0, zone DMA32 > spanned 246652 > present 245868 > managed 222816 # +43,949 pages > > Fixes: 3a80a7fa7989 ("mm: meminit: initialise a subset of struct pages if CONFIG_DEFERRED_STRUCT_PAGE_INIT is set") > Signed-off-by: Aaron Thompson Applied, thanks! > --- > mm/memblock.c | 8 +++++++- > tools/testing/memblock/internal.h | 4 ++++ > 2 files changed, 11 insertions(+), 1 deletion(-) > > diff --git a/mm/memblock.c b/mm/memblock.c > index 511d4783dcf1..fc3d8fbd2060 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -1640,7 +1640,13 @@ void __init memblock_free_late(phys_addr_t base, phys_addr_t size) > end = PFN_DOWN(base + size); > > for (; cursor < end; cursor++) { > - memblock_free_pages(pfn_to_page(cursor), cursor, 0); > + /* > + * Reserved pages are always initialized by the end of > + * memblock_free_all() (by memmap_init() and, if deferred > + * initialization is enabled, memmap_init_reserved_pages()), so > + * these pages can be released directly to the buddy allocator. > + */ > + __free_pages_core(pfn_to_page(cursor), 0); > totalram_pages_inc(); > } > } > diff --git a/tools/testing/memblock/internal.h b/tools/testing/memblock/internal.h > index fdb7f5db7308..85973e55489e 100644 > --- a/tools/testing/memblock/internal.h > +++ b/tools/testing/memblock/internal.h > @@ -15,6 +15,10 @@ bool mirrored_kernelcore = false; > > struct page {}; > > +void __free_pages_core(struct page *page, unsigned int order) > +{ > +} > + > void memblock_free_pages(struct page *page, unsigned long pfn, > unsigned int order) > { > -- > 2.30.2 > -- Sincerely yours, Mike.